Search

A previous study on the encroachment of North American northern red oak Quercus rubra L. into the mesic Scots pine forest (in central Poland) revealed high abundances of seedlings and saplings under shrubs, with lower abundances in open areas or clumps of bilberry Vaccinium myrtillus L. It was unclear whether the regeneration success of Q. rubra is enhanced by the presence of shrubs due to their "nurse effect", and how burying acorns of different sizes in soil or moss affects the survival of oak seeds and seedlings (a "burial effect"). Results of a previous observational study were verified in an experimental study: a pool of 900 large‐, medium‐, and small‐sized acorns was sown under moss cover in open areas and within bilberry clumps and in soil under shrubs in 2018 and monitored for 3 years in natural conditions. The majority of sown acorns were lost, mainly due to acorn pilferage, lack of germination and the death of sprouting acorns. However, acorn and seedling survival depended significantly on acorn size and differed among the microsites studied. Viable seedlings were twice as likely to develop from large‐ and medium‐sized as from small‐sized acorns, and they grew mainly from acorns sown under moss cover, confirming a positive "burial effect." Seedling survival was three times higher in bilberry and open areas, than under shrubs; however, seedlings "nursed" by shrubs were less threatened by large ungulates. Only a small part of the pool of sown acorns contributes to the reproductive success of Q. rubra in the mesic Scots pine forest. Microsites characteristic to this type of forest are suitable for northern red oak regeneration; however, bilberry favors acorn survival and germination and early seedling growth, moss cover favors acorn survival and germination, while shrubs protect surviving seedlings from herbivory. [ABSTRACT FROM AUTHOR]

Abstract A previous study on the encroachment of North American northern red oak Quercus rubra L. into the mesic Scots pine forest (in central Poland) revealed high abundances of seedlings and saplings under shrubs, with lower abundances in open areas or clumps of bilberry Vaccinium myrtillus L. It was unclear whether the regeneration success of Q. rubra is enhanced by the presence of shrubs due to their “nurse effect”, and how burying acorns of different sizes in soil or moss affects the survival of oak seeds and seedlings (a “burial effect”). Results of a previous observational study were verified in an experimental study: a pool of 900 large‐, medium‐, and small‐sized acorns was sown under moss cover in open areas and within bilberry clumps and in soil under shrubs in 2018 and monitored for 3 years in natural conditions. The majority of sown acorns were lost, mainly due to acorn pilferage, lack of germination and the death of sprouting acorns. However, acorn and seedling survival depended significantly on acorn size and differed among the microsites studied. Viable seedlings were twice as likely to develop from large‐ and medium‐sized as from small‐sized acorns, and they grew mainly from acorns sown under moss cover, confirming a positive “burial effect.” Seedling survival was three times higher in bilberry and open areas, than under shrubs; however, seedlings “nursed” by shrubs were less threatened by large ungulates. Only a small part of the pool of sown acorns contributes to the reproductive success of Q. rubra in the mesic Scots pine forest. Microsites characteristic to this type of forest are suitable for northern red oak regeneration; however, bilberry favors acorn survival and germination and early seedling growth, moss cover favors acorn survival and germination, while shrubs protect surviving seedlings from herbivory.

Kuraklık stresi, pek çok kültür bitkisinde olduğu gibi taze fasulye üretimini de sınırlayan başlıca faktörlerden biridir. Son zamanlarda düşük dozda gama ışını uygulamalarının bitki gelişiminin kritik aşamalarında kuraklığın oluşturduğu olumsuz etkinin elemine edilmesinde yardımcı olduğu bazı araştırmacılar tarafından bildirilmiştir. Fakat bu konuda yapılan çalışmalar oldukça sınırlıdır. Bu çalışmada farklı gama ışın dozları (0, 25, 50 ve 100 Gy) uygulanan Gina ve Romano taze fasulye çeşitlerinde kısıtlı sulamanın etkilerinin belirlenmesi amaçlanmıştır. Fideler iklim odası koşullarında 23 ± 2°C sıcaklık ve 16:8 ışık:karanlık periyodunda tam sulama [%100 (I1)] ve kısıtlı sulama [%50 (I2)] olacak şekilde iki farklı sulama seviyesinde yetiştirilmişlerdir. Çalışma sonunda gama ışını dozları ile kısıtlı sulamanın sürgün ve kök boyu, yaprak sayısı, sürgün ve kök yaş-kuru ağırlıkları, kök-sürgün oranı gibi fide gelişim parametrelerinin yanı sıra yaprak oransal su içeriği, fotosentetik pigment içeriği, lipid peroksidasyonu ve sürgün besin elementi içeriklerine etkisi araştırılmıştır. Çalışmada düşük doz gama uygulamasının kısıtlı sulama koşullarında çeşitlere göre farklı sonuçlar verdiği görülmüştür. Gama ışın dozları %50 sulamada Gina çeşidinde kök boyunda önemli bir etki yaratırken, Romano çeşidinde 50 ve 100 Gy dozlarının sürgün boyu ile yaş ve kuru ağırlıklarda önemli bir artış sağlamıştır. MDA içeriği her iki çeşitte de su stresinde 50 ve 100 Gy gama ışını ile birlikte önemli miktarda azalmıştır. Düşük doz gama ışını uygulamasının özellikle Romano çeşidinde daha etkili olduğu ve genel olarak 50 ve 100 Gy gama ışın dozlarının kısıtlı sulamada uygulanabilir dozlar olduğu belirlenmiştir.

SUMMARY: The signaling pathways for the phytohormones ethylene and abscisic acid (ABA) have antagonistic effects on seed germination and early seedling establishment. However, the underlying molecular mechanisms remain unclear. In Arabidopsis thaliana, ETHYLENE INSENSITIVE 2 (EIN2) localizes to the endoplasmic reticulum (ER); although its biochemical function is unknown, it connects the ethylene signal with the key transcription factors EIN3 and EIN3‐LIKE 1 (EIL1), leading to the transcriptional activation of ethylene‐responsive genes. In this study, we uncovered an EIN3/EIL1‐independent role for EIN2 in regulating the ABA response. Epistasis analysis demonstrated that this distinct role of EIN2 in the ABA response depends on HOOKLESS 1 (HLS1), the putative histone acetyltransferase acting as a positive regulator of ABA responses. Protein interaction assays supported a direct physical interaction between EIN2 and HLS1 in vitro and in vivo. Loss of EIN2 function resulted in an alteration of HLS1‐mediated histone acetylation at the ABA‐INSENSITIVE 3 (ABI3) and ABI5 loci, which promotes gene expression and the ABA response during seed germination and early seedling growth, indicating that the EIN2–HLS1 module contributes to ABA responses. Our study thus revealed that EIN2 modulates ABA responses by repressing HLS1 function, independently of the canonical ethylene pathway. These findings shed light on the intricate regulatory mechanisms underling the antagonistic interactions between ethylene and ABA signaling, with significant implications for our understanding of plant growth and development. Significance Statement: Here we found an unexpected role of EIN2 in the antagonistic interactions between ethylene and ABA in seed germination and early seedling growth, different from its well‐established role in the classic ethylene signaling pathway. Our work demonstrates that EIN2 physically interacts with the putative histone acetyltransferase HLS1, thus repressing histone H3 acetylation on ABI5 and ABI3 chromatin to fine‐tune ABA signaling. [ABSTRACT FROM AUTHOR]

Drought is a major abiotic constraint on rice (Oryza sativa L.) production in Malaysia. Malaysian Agricultural Research and Development Institute (MARDI) has released more than 50 indica rice genotypes so far. However, little has been studied about their drought tolerance. The study aimed to evaluate the germination and early seedling growth performances of 15 rice genotypes under polyethylene glycol (PEG) 6000-induced drought stresses. Four osmotic potentials of PEG 6000 (0, -0.3, -0.6, -0.9 MPa) were used in the study denoted as control, low, moderate and severe stresses respectively. Data on seed germination percentage, germination index, germination energy, germination rate, seedling height, seedling vigor I and II, fresh and dry weight of seedlings were measured. Studied parameters varied greatly among genotypes with different osmotic stresses. The findings suggested most of the rice genotypes showed an apparent reduction in germination and growth traits, while MR211 showed less reduction under all of the stresses. The Multivariate clustering grouped genotypes into five different clusters, where cluster V (MR220, MR269, MR253, MR297, MR303 and MR284) incorporated six genotypes showed better germination and growth under different osmotic potentials, followed by cluster IV (MR211 and MR307). Cluster II incorporated one genotype MARDI WARNA98 which had minimal germination and growth attributes. Principal component analysis (PCA) was performed to identify the maximum contributing variables for diversity, revealed maximum variation by first two components (81.8% and 7.7%) respectively. Therefore, PEG 6000 can be used as an efficient tool for discrimination and identification of drought tolerance in rice. [ABSTRACT FROM AUTHOR]

Auxin is well known to stimulate coleoptile elongation and rapid seedling growth in the air. However, its role in regulating rice germination and seedling establishment under submergence is largely unknown. Previous studies revealed that excessive levels of indole‐3‐acetic acid(IAA) frequently cause the inhibition of plant growth and development. In this study, the high‐level accumulation of endogenous IAA is observed under dark submergence, stimulating rice coleoptile elongation but limiting the root and primary leaf growth during anaerobic germination (AG). We found that oxygen and light can reduce IAA levels, promote the seedling establishment and enhance rice AG tolerance. miRNA microarray profiling and RNA gel blot analysis results show that the expression of miR167 is negatively regulated by submergence; it subsequently modulates the accumulation of free IAA through the miR167‐ARF‐GH3 pathway. The OsGH3‐8 encodes an IAA‐amido synthetase that functions to prevent free IAA accumulation. Reduced miR167 levels or overexpressing OsGH3‐8 increase auxin metabolism, reduce endogenous levels of free IAA and enhance rice AG tolerance. Our studies reveal that poor seed germination and seedling growth inhibition resulting from excessive IAA accumulation would cause intolerance to submergence in rice, suggesting that a certain threshold level of auxin is essential for rice AG tolerance. Summary statement: Excessive auxin accumulation negatively affects rice AG. Conversely, oxygen and light significantly reduce IAA levels, promote the seedling establishment during AG, and submergence‐repressed miR167 reduces IAA levels through miR167‐ARF‐GH3 pathway and enhances AG tolerance. [ABSTRACT FROM AUTHOR]

Gynomonoecy, the occurrence of both pistillate (female) and perfect (hermaphroditic) flowers on the same plant, has received little attention compared to gynodioecy and other plant sexual systems. Eremurus anisopterus is a perennial ephemeral in the cold desert of northwest China with a hermaphrodite–gynomonoecious sexual system in the same population. The primary aim of this study was to compare the early life history traits and inbreeding depression between progeny from pistillate and hermaphrodite flowers in hermaphrodites and gynomonoecious individuals. All of the traits of progeny from outcrossed pistillate flowers on gynomonoecious plants were significantly greater than for other pollination types. Selfing (vs. outcrossing) resulted in a decrease in all traits, indicating inbreeding depression (ID) during early life history stages of gynomonoecious and hermaphroditic plants. ID for seed mass, seed germination and seedling survivorship under water stress for pistillate flowers on gynomonoecious plants was significantly higher than it was for hermaphrodite flowers on both gynomonoecious and hermaphrodite plants. The advantage of the offspring of pistillate (vs. hermaphrodite) flowers may contribute to the maintenance of gynomonoecy in E. anisopterus in its cold desert sand dune habitat. [ABSTRACT FROM AUTHOR]

This study was conducted to provide reference for plant landscaping, optimization of planting structure and rational allocation of species in Cedrus deodcua gardens. [Methods] With three common garden plants in northern China, Trifolium repens L, Poa pralensis L and Trifolium pralense L, as receptors, the effects of four concentrations ( 0.025, 0. 05, 0.075 and 0.10 g/ml) of C. deodara needle extract on seed germination and early seedling growth of the three turf grasses were studied by the Petri dish filter paper method, using a clear water treatment ( 0 g/ml) as control check (CK). Data were subjected to analysis of variance ( ANOVA) and multiple comparisons (Duncan) using SPSS16. 0. [Results] Different concentrations of C. deodcua needle extract had significant inhibitory effects on seed germination, radicle and seedling height growth of T. repens, T. pratense and P. pratensis ( P < 0.05 ), and the inhibitory effects increased with the increase of concentration. When the concentration reached 0. 075 g/ ml, seed germination and seedling growth of T. repens stopped, and radicle and seedling growth of T. pratense and P. pralensis also stopped. When the concentration was equal to 0.10 g/ ml, germination of T. pralense and P. pralensis seeds was inhibited, and the absolute values of allelopathic index was the largest, that is, the inhibitory effects were the largest. And with the increase of concentration, the absolute value of synthetical allelopathic index also increased. The extract of C. deodcua needles contained main allelochemicals leading to the scarcity of understory vegetation. [Conclusions] This study provides a theoretical basis for reasonable garden plant configuration during C. deodara greening and garden landscaping. [ABSTRACT FROM AUTHOR]

A common practice to enhance seed quality for direct seeding of rice is priming under unfavorable designated conditions. This study aims to increase germination performance and early seedling growth of the MR219 rice by determining optimum priming times and ideal concentrations of gibberellic acid (GA3). Seeds were primed with GA3 in concentrations ranging from 20, 40, 60, 80 and 100 mg/L for 12 and 18 hours separately, and unprimed seeds served as control. The germination test was measured using a completely randomized design (CRD); meanwhile, pot cultivation was carried out using a randomized complete block design (RCBD) for four weeks. In germination studies, it was found that seeds primed with GA3 for 12 hours at 60 mg/L significantly enhanced the germination performance, and early seedling growth of MR219 compared to unprimed seeds. The primed seeds had a germination percentage between 90-100%, increased seed vigor and germination indexes 3-fold and 2-fold respectively, and reduced the mean germination time by 24 hours. Correspondingly, in pot cultivation, the establishment and early seedling growth of primed MR219 was significantly increased as the seedling height, and total fresh weight was two times higher than unprimed seedlings. In addition, the biochemical attributes of GA3 primed seedlings, including total soluble sugar, carbohydrate, and total soluble protein, were significantly increased by 2-, 1.6- and 4-folds, respectively, compared to unprimed seedlings. Priming MR219 seeds with GA3 at 60 mg/L for 12 hours was found to significantly enhance the germination performance and early seedling growth in pot cultivation of direct-seeded rice as it promoted vigorous seedling growth of the MR219 rice cultivar.

Copyright of Mustafa Kemal University Journal of Agricultural Sciences / Mustafa Kemal Üniversitesi Tarım Bilimleri Dergisi is the property of Mustafa Kemal University, Faculty of Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abscisic acid (ABA) is an important phytohormone regulating plant growth, development and stress responses. A multitude of key factors implicated in ABA signaling have been identified; however, the regulation network of these factors needs for further information. AtS40.4, a plant-specific DUF584 domain-containing protein, was identified previously as a senescence regulator in Arabidopsis. In this study, our finding showed that AtS40.4 was negatively involved in ABA signaling during seed germination and early seedling growth. AtS40.4 was highly expressed in seeds and seedlings, and the expression level was promoted by ABA. AtS40.4 was localized both in the nucleus and the cytoplasm. Moreover, the subcellular localization pattern of AtS40.4 was affected by ABA. The knockdown mutants of AtS40.4 exhibited an increased sensitivity to ABA, whereas the overexpression of AtS40.4 decreased the ABA response during seed germination and seedling growth of Arabidopsis. Furthermore, AtS40.4 was involved in ABRE-dependent ABA signaling and influenced the expression levels of ABA INSENTIVE (ABI) 1-5 and SnRK2.6. Further genetic evidence demonstrated that AtS40.4 functioned upstream of ABI4. These findings support the notion that AtS40.4 is a novel negative regulator of the ABA response network during seed germination and early seedling growth. [ABSTRACT FROM AUTHOR]

Gynomonoecy, the occurrence of both pistillate (female) and perfect (hermaphroditic) flowers on the same plant, has received little attention compared to gynodioecy and other plant sexual systems. Eremurus anisopterus is a perennial ephemeral in the cold desert of northwest China with a hermaphrodite–gynomonoecious sexual system in the same population. The primary aim of this study was to compare the early life history traits and inbreeding depression between progeny from pistillate and hermaphrodite flowers in hermaphrodites and gynomonoecious individuals. All of the traits of progeny from outcrossed pistillate flowers on gynomonoecious plants were significantly greater than for other pollination types. Selfing (vs. outcrossing) resulted in a decrease in all traits, indicating inbreeding depression (ID) during early life history stages of gynomonoecious and hermaphroditic plants. ID for seed mass, seed germination and seedling survivorship under water stress for pistillate flowers on gynomonoecious plants was significantly higher than it was for hermaphrodite flowers on both gynomonoecious and hermaphrodite plants. The advantage of the offspring of pistillate (vs. hermaphrodite) flowers may contribute to the maintenance of gynomonoecy in E. anisopterus in its cold desert sand dune habitat.

Signaling by the phytohormone abscisic acid (ABA) involves pre-mRNA splicing, a key process of post-transcriptional regulation of gene expression. However, the regulatory mechanism of alternative pre-mRNA splicing in ABA signaling remains largely unknown. We previously identified a pentatricopeptide repeat protein SOAR1 (suppressor of the ABAR-overexpressor 1) as a crucial player downstream of ABAR (putative ABA receptor) in ABA signaling. In this study, we identified a SOAR1 interaction partner USB1, which is an exoribonuclease catalyzing U6 production for spliceosome assembly. We reveal that together USB1 and SOAR1 negatively regulate ABA signaling in early seedling development. USB1 and SOAR1 are both required for the splicing of transcripts of numerous genes, including those involved in ABA signaling pathways, suggesting that USB1 and SOAR1 collaborate to regulate ABA signaling by affecting spliceosome assembly. These findings provide important new insights into the mechanistic control of alternative pre-mRNA splicing in the regulation of ABA-mediated plant responses to environmental cues. [ABSTRACT FROM AUTHOR]

A common practice to enhance seed quality for direct seeding of rice is priming under unfavorable designated conditions. This study aims to increase germination performance and early seedling growth of the MR219 rice by determining optimum priming times and ideal concentrations of gibberellic acid (GA3). Seeds were primed with GA3 in concentrations ranging from 20, 40, 60, 80 and 100 mg/L for 12 and 18 hours separately, and unprimed seeds served as control. The germination test was measured using a completely randomized design (CRD); meanwhile, pot cultivation was carried out using a randomized complete block design (RCBD) for four weeks. In germination studies, it was found that seeds primed with GA3 for 12 hours at 60 mg/L significantly enhanced the germination performance, and early seedling growth of MR219 compared to unprimed seeds. The primed seeds had a germination percentage between 90-100%, increased seed vigor and germination indexes 3-fold and 2-fold respectively, and reduced the mean germination time by 24 hours. Correspondingly, in pot cultivation, the establishment and early seedling growth of primed MR219 was significantly increased as the seedling height, and total fresh weight was two times higher than unprimed seedlings. In addition, the biochemical attributes of GA3 primed seedlings, including total soluble sugar, carbohydrate, and total soluble protein, were significantly increased by 2-, 1.6- and 4-folds, respectively, compared to unprimed seedlings. Priming MR219 seeds with GA3 at 60 mg/L for 12 hours was found to significantly enhance the germination performance and early seedling growth in pot cultivation of direct-seeded rice as it promoted vigorous seedling growth of the MR219 rice cultivar. [ABSTRACT FROM AUTHOR]

This study focused on the effect of saline and alkaline stress on six typical wetland plant species during seed germination and early seedling growth stages. Based on the indicators of germination, seedling growth and ionic absorption in seedlings, relatively saline and alkaline tolerant plant species were selected and tolerance mechanism was discussed. Results showed that the existence of saline and alkaline stress inhibited the capacity of germination and early seedling growth of most tested plant species to varying degrees, therein effects of saline-alkaline stress were greater than saline stress. Based on the results of principal component analysis (PCA), germination percentage, K+ content, plant height, Na+ content and Na+/K+ ratios can be selected as representative indicators for saline and alkaline tolerance evaluation during seed germination and early seedling growth stages. Among tested species, Juncus effusus and Vetiveria zizanioides exhibited relatively higher saline and alkaline tolerant capacity during their seed germination and early seedling growth. Additionally, both species increase K+ accumulation and retain lower Na+/K+ ratios, which might be their tolerance mechanisms at ion level. In conclusion, V. zizaniodes and J. effusus were recommended as potential plant species for restoring degraded saline-alkaline wetlands and/or establishing constructed wetlands for treating saline wastewater. [ABSTRACT FROM AUTHOR]

Seeds of three sorghum (Sorghum bicolor (L.) Moench.) varieties from southwest Saudi Arabia were used to investigate the potential of osmopriming with polyethylene glycol (PEG 8000) to improve germination performance, seed reserve utilization and early seedling growth and drought stress tolerance. The primed (PS) and unprimed (UPS) seeds of the three sorghum varieties were germinated for 8 days under increasing PEGinduced osmotic stress. The treatments were arranged in a completely randomized design, in a factorial arrangement, with three sorghum cultivars ('Zaydia', 'Shahbi and 'Ahmar') and four osmotic potentials (0.0; - 0.4; -0.8 and -1.2 MPa) with four replicates of 50 seeds each. The results showed that drought stress affected seed germination and seedling emergence and establishment, but increased the activity of the antioxidant enzyme catalase (CAT). The strongest inhibition of germination and growth occurred at the highest PEG concentration and a significant difference was noticeable between the studied varieties. We confirmed also that seed osmopriming improved seed germination performance, seedling growth and enhanced the CAT activities while reduced malonyldialdehyde (MDA) accumulation and electrolyte leakage (EL) in the drought-stressed seedlings. Seed priming have enhanced also the α-amylase and total proteases activities in all varieties. The largest increase of these hydrolysing enzymes was shown in 'Ahmar'. Furthermore, the PEG priming lead to improvement of the weight of utilized (mobilized) seed reserve (WUSR), seed reserve depletion percentage (SRDP), and total seedling dry weight (SLDW) of sorghum seedlings under water stress conditions. Still the highest values or all three parameters were found in the 'Ahmar' variety. Under increasing drought stress conditions, 'Ahmar' showed the highest yield stability index (YSI) and the least EL and MDA contents in comparison to the other two varieties during the seedling establishment stage. Therefore, the former variety can tolerate better a rigorous water stress condition. 'Zaydia' appears to be the most vulnerable to drought stress. Thus, the use of species or varieties with eminent seed metabolic quality is an advantageous trait in drought-prone regions. [ABSTRACT FROM AUTHOR]

Seed germination and early seedling growth are important agricultural traits for developing populations of both irrigated and directly seeded rice (DSR). To investigate the genetic mechanisms underlying seed germination and early seedling growth in rice, 275 recombinant inbred lines (RILs) were genotyped in this study via the genotyping-by-sequencing (GBS) approach to construct a high-density linkage bin map based on the parent-independent genotyping method. Quantitative trait loci (QTLs) for 12 traits related to seed germination and early seedling growth were analyzed. Totally, 22 additive loci were detected, after analysis of the interaction between additive QTLs and environments, five stable additive loci were obtained. Among them, loci 4, 5, 12 and 14 exhibited clear pleiotropic effects that were associated with multiple traits. Analysis of the effects of the five additive stable loci showed that a single locus increased the corresponding phenotypic value. Ten of the 275 RILs pyramided the excellent alleles of the five stable genetic loci. Most phenotypic values of the ten RILs were greater than the average values. Four RILs (G260, G342, G371, and G401) with more excellent phenotypic values were subsequently selected; these RILs could serve as donor parents of favorable alleles in the breeding process. Due to the existence of pleiotropy, the use of these genetic loci for pyramid breeding can further increase the efficiency to reach breeding goals. In addition, these five stable loci have an average physical interval of only 170 kb, we also further identified five promising candidate genes by qRT-PCR, which provides us with a basis for future cloning of these genes. Overall, this work will help broaden our understanding of the genetic control of seed germination and early seedling growth, and this study provides both a good theoretical basis and a new genetic resource for the breeding of direct-seeded rice.

Seed germination and early seedling growth are important agricultural traits for developing populations of both irrigated and directly seeded rice (DSR). To investigate the genetic mechanisms underlying seed germination and early seedling growth in rice, 275 recombinant inbred lines (RILs) were genotyped in this study via the genotyping-by-sequencing (GBS) approach to construct a high-density linkage bin map based on the parent-independent genotyping method. Quantitative trait loci (QTLs) for 12 traits related to seed germination and early seedling growth were analyzed. Totally, 22 additive loci were detected, after analysis of the interaction between additive QTLs and environments, five stable additive loci were obtained. Among them, loci 4, 5, 12 and 14 exhibited clear pleiotropic effects that were associated with multiple traits. Analysis of the effects of the five additive stable loci showed that a single locus increased the corresponding phenotypic value. Ten of the 275 RILs pyramided the excellent alleles of the five stable genetic loci. Most phenotypic values of the ten RILs were greater than the average values. Four RILs (G260, G342, G371, and G401) with more excellent phenotypic values were subsequently selected; these RILs could serve as donor parents of favorable alleles in the breeding process. Due to the existence of pleiotropy, the use of these genetic loci for pyramid breeding can further increase the efficiency to reach breeding goals. In addition, these five stable loci have an average physical interval of only 170 kb, we also further identified five promising candidate genes by qRT-PCR, which provides us with a basis for future cloning of these genes. Overall, this work will help broaden our understanding of the genetic control of seed germination and early seedling growth, and this study provides both a good theoretical basis and a new genetic resource for the breeding of direct-seeded rice. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effect of metals on wheat and bean species. The method uses seed germination and early seedling growth of these plants in the presence of various levels (10, 50, 100, 250, 500, 750 and 1000 mg/L) of Cadmium (Cd), Iron (Fe) and Zinc (Zn). The inhibition caused by these metals was depending on the concentration used, the metal itself and the plant species. The species had reduced seed germination, root and shoot lengths, tolerance index and percentphyto-toxicity with increasing concentrations of metals. Cadmium was determined to be the most inhibitory metal on these parameters. This metal affected significantly the germination, root and shoot length of the species tested, as well as the tolerance index and percentphytotoxicity starting from 50 mg Cd/l. Under the Iron stress, in general, the inhibition of germination and root length of wheat was reduced from 500 mg Fe/l. The results showed also that the inhibitory effect of increase of Zn levels was seen in root, shoot and tolerance indices. The findings also revealed that the metal toxicity was as follow: Cd > Fe > Zn. Regarding species, the results showed that bean seemed to be more tolerant to the increase of the three metals than wheat.

Seed germination and early seedling development have been studied in the recalcitrant species Quercus ilex using targeted transcriptional, hormonal, and sugar analysis. Embryos and seedlings were collected at eight morphologically defined developmental stages, S0–S7. A typical triphasic water uptake curve was observed throughout development, accompanied by a decrease in sucrose and an increase in glucose and fructose. Low levels of abscisic acid (ABA) and high levels of gibberellins (GAs) were observed in mature seeds. Post-germination, indole-3-acetic acid (IAA), increased, whereas GA remained high, a pattern commonly observed during growth and development. The abundance of transcripts from ABA-related genes was positively correlated with the changes in the content of the phytohormone. Transcripts of the drought-related genes Dhn3 and GolS were more abundant at S0, then decreased in parallel with increasing water content. Transcripts for Gapdh, and Nadh6 were abundant at S0, supporting the occurrence of an active metabolism in recalcitrant seeds at the time of shedding. The importance of ROS during germination is manifest in the high transcript levels for Sod and Gst, found in mature seeds. The results presented herein help distinguish recalcitrant (e.g., Q. ilex) seeds from their orthodox counterparts. Our results indicate that recalcitrance is established during seed development but not manifest until germination (S1–S3). Post-germination the patterns are quite similar for both orthodox and recalcitrant seeds.

Seed germination and early seedling development have been studied in the recalcitrant species Quercus ilex using targeted transcriptional, hormonal, and sugar analysis. Embryos and seedlings were collected at eight morphologically defined developmental stages, S0–S7. A typical triphasic water uptake curve was observed throughout development, accompanied by a decrease in sucrose and an increase in glucose and fructose. Low levels of abscisic acid (ABA) and high levels of gibberellins (GAs) were observed in mature seeds. Post-germination, indole-3-acetic acid (IAA), increased, whereas GA remained high, a pattern commonly observed during growth and development. The abundance of transcripts from ABA-related genes was positively correlated with the changes in the content of the phytohormone. Transcripts of the drought-related genes Dhn3 and GolS were more abundant at S0, then decreased in parallel with increasing water content. Transcripts for Gapdh , and Nadh6 were abundant at S0, supporting the occurrence of an active metabolism in recalcitrant seeds at the time of shedding. The importance of ROS during germination is manifest in the high transcript levels for Sod and Gst, found in mature seeds. The results presented herein help distinguish recalcitrant (e.g., Q. ilex) seeds from their orthodox counterparts. Our results indicate that recalcitrance is established during seed development but not manifest until germination (S1–S3). Post-germination the patterns are quite similar for both orthodox and recalcitrant seeds. [ABSTRACT FROM AUTHOR]

Pre-sowing treatments are expected to increase seed germination. This evaluates response to pre-sowing treatments and the growth performance of two native and rare tree species, Garuga pinnata Roxb. and Vitex glabrata R. Br. The hard seed coats were treated by rubbing with sand paper, nail clipping, and immersion in water and acid (H2SO4). Results indicate that G. pinnata showed a 90% germination rate and 30% germination energy when seed coats were nicked with a nail clipper. Rubbing with sand paper was the best pre-sowing treatment for V. glabrata, resulting a 80% germination rate and 30% germination energy. G. pinnata and V. glabrata seedlings from seeds soaked 24 h in water resulted in maximum heights and collar diameters. These were significantly higher (at p < 0.05) than those of other treatments. The results indicate that scarification or nicking of seeds may have some negative impacts on seedling growth. Therefore, it is difficult to recommend a pre-sowing treatment of seeds for achieving both maximum germination and good early seedling growth. [ABSTRACT FROM AUTHOR]

The salt stress affects plant growth and physiological characteristics during early growth stages in rice (Oryza sativa L.) The objective of this study was to examine the influence of salt stress on rice growth during early stages and to find out their salt tolerance levels. A pot culture experiment was conducted in rice cropping season 2016, with completely randomized design (CRD) and three replicates. The treatments were two rice cultivars, 'Liangyoupeijiu' (LYP9) and 'Nipponbare' (NPBA) with four salt stress levels 0 (control, CK), 1.5 (low salt stress, LS), 4.5 (medium salt stress, MS), and 7.5 g (heavy salt stress, HS) NaCl kg-1 soil at different growth stages with six seedlings per pot. About 15 parameters were recorded and most of the treatments were significantly different (P ≤ 0.05) from each other. The results showed that salt stress reduced seed emergence characteristics of the rice. It also decreased photosynthetic parameters, growth characteristics including DM, and seedling height reduction increased at early seedling and maximum tillering stage in both rice cultivars but this disaster is less in 'LYP9' than 'NPBA'. On the basis of DM reduction, 'LYP9' was categorized as moderately susceptible (MS) and susceptible (S) at HS during early growth stage, and 'NPBA' was categorized as sensitive to the HS stress level. The result suggested that 'LYP9' showed somehow resistance under salt stress than 'NPBA'. This study will help us to provide new ideas for improving the high yielding rice cultivar (LYP9) to salt tolerance by genetic modification and cultivation techniques. [ABSTRACT FROM AUTHOR]

Red clover is highly salt-sensitive plant, especially during germination and early seedling growth stages. The aim of this investigation was to estimate the effects of different saline conditions (0, 50, 100, 150, and 200mM NaCl) on germination and early seedling growth in four red clover varieties (Kolubara, K-32, K-17 and K-39). Germination test was conducted in the laboratory conditions using sterile plastic vessels on filter paper moistened with 10ml of the appropriate salt test solutions. It was observed that the germination energy (GE), germination (G), percentage of dead or infected seeds (DIS), normal seedlings (NS), root length (RL), shoot length (ShL), fresh weight (FW) and dry weight of seedling (DW) and seedling vigor index (SVI) were significantly decreased with increasing concentrations of NaCl in the growing medium. The tested varieties of red clover showed different NaCl tolerance at the seedling stage. Generally, studied red clover varieties are very sensitive to salt, especially K-32 which has the lowest values for GE, G, NS and SVI and highest for DIS. Variety K-17 proved to be a variety that the best tolerates conditions of salt stress because the values for GE, G, NS, RL and SVI were highest. Testing of varieties of red clover in the early seedling growth at different concentrations of NaCl in the growing medium could be helpful in the identification and selection of varieties for cultivation on saline soils.

The aim of this research was to estimate the influence of different NaCl osmotic solutions (0, -0.3 MPa, -0.6 MPa, -0.9 MPa, -1.2 MPa, -1.5 MPa) on seed germination, and early seedling growth in two maize hybrid different maturity groups (ZP 560 - FAO 500 and ZP 666 - FAO 600). Germination was tested in sterile plastic vessels on filter paper moistened with different NaCl solutions, in the dark at 20 ± 1°C, in laboratory. Results of ANOVA indicated that hybrid ZP 666 had significantly higher root length (RL) (6.37 cm), shoot length (ShL) (2.06 cm), shoot fresh weight (ShFW) (43.86 mg), root dry weight (RDW) (7.56 mg), shoot dry weight (ShDW) (5.97 mg), seedling vigor index (SVI) (706.55) and dry matter stress tolerance index (DMSI) (55.85%) than hybrid ZP 560 (4.18 cm, 1.14 cm, 32.50 mg, 6.54 mg, 4.15 mg, 457.61 and 48.86%, respectively). Contrary, hybrid ZP 560 had significantly higher relative seedling water content (RSWC) (83.83%) and phytotoxicity of shoot (PhSh) (69.77%) than hybrid ZP 666 (81.16% and 62.51%, respectively). Generally, hybrid ZP 666 had better tolerance to salt stress than hybrid ZP 560. Germination energy (GE), germination (G), RL, ShL, root fresh weight (RFW), ShFW, RDW, ShDW, rate germination index (RGI), SVI, RSWC and DMSI were significantly decreased with the increase in osmotic stress induced by NaCl. Contrary, phytotoxicity of root (PhR) and PhSh significantly increased with the increase in osmotic stress.

Increased fatty acid β-oxidation is essential for early postgerminative growth in seedlings, but high levels of H2O2 produced by β-oxidation can induce oxidative stress. Whether and how catalase (CAT) functions in fine-tuning H2O2 homeostasis during seedling growth remain unclear. Here, we report that CAT2 functions in early seedling growth. Compared to the wild type, the cat2-1 mutant, with elevated H2O2 levels, exhibited reduced root elongation on sucrose (Suc)-free medium, mimicking soils without exogenous sugar supply. Treatment with the H2O2 scavenger potassium iodide rescued the mutant phenotype of cat2-1. In contrast to the wild type, the cat2-1 mutant was insensitive to the CAT inhibitor 3-amino-1,2,4-triazole in terms of root elongation when grown on Suc-free medium, suggesting that CAT2 modulates early seedling growth by altering H2O2 accumulation. Furthermore, like cat2-1, the acyl-CoA oxidase (ACX) double mutant acx2-1 acx3-6 showed repressed root elongation, suggesting that CAT2 functions in early seedling growth by regulating ACX activity, as this activity was inhibited in cat2-1. Indeed, decreased ACX activity and short root of cat2-1 seedlings grown on Suc-free medium were rescued by overexpressing ACX3. Together, these findings suggest that CAT2 functions in early seedling growth by scavenging H2O2 and stimulating ACX2/3 activity. [ABSTRACT FROM AUTHOR]

Low temperature is a limiting factor of seed germination and plant growth. In this study, two independent experiments were conducted to investigate the effects of low temperature on germination, early seedling growth and antioxidant systems in two provenances of Elymus nutans Griseb. (Damxung, DX and Gannan, GN). The seeds and early seedlings of DX were more tolerant to low temperture than those of GN. Low temperature (5°C) negatively affected seed Germination Percentage (GP), Germination Energy (GE) and the First Germination Time (FGT) in both provenances of E. nutans. Low temperature also increased Mortality Percentage (MP) when compared with control plants grown at 25°C. Low temperature treatments significantly reduced length and fresh/dry weight of shoots and roots in the two accessions after 29 days of exposure to 5°C. In the second experiment, after 5 days of low temperature treatment, DX exhibited significantly higher Chlorophyll (Chl) and Carotenoid (Car) content as well as increased activities of Peroxidase (POD), SuperOxide Dismutase (SOD), Catalase (CAT). In contrast we observed lower Electrolyte Leakage (EL) and reduction of the amounts of MalonDiAldehyde (MDA), Hydrogen peroxide (H2O2) and superoxide radical ( O•- 2 ). We conclude that GN is more susceptible to low temperature than DX due to more severe oxidative damage resulting from Reactive Oxygen Species (ROS) and lower antioxidant enzyme activities. [ABSTRACT FROM AUTHOR]

Water deficit is an environmental factor that constrains crops to express their ecophysiological potential and causes crop yield reduction. Eruca vesicaria has been reported to be one of the most drought-tolerant species in Cruciferae. In this study, polyethylene glycol-simulated drought tolerance was evaluated in one line of Brassica carinata, one line of Brassica napus and 249 Eruca lines based on the principal component analysis (PCA) and unweighted pair-group arithmetic average (UPGMA) cluster analysis. The PCA based on eight drought tolerance indices indicated that the first three components accounted for 85.46% of the total variation, with principal component (PC) 1 accounting for 43.89%, PC2 for 27.85% and PC3 for 13.73% of the total variation. The UPGMA cluster analysis indicated that B. napus cultivar Zhongshuang 9 and Eruca lines could be clustered into five major groups, with group 1 being, in general, drought sensitive, group 2 being slightly–medium drought tolerant, group 3 being drought tolerant, group 4 being highly drought sensitive and group 5 being highly drought tolerant. B. carinata cultivar XB1, as an outstander, showed high drought sensitivity. The UPGMA cluster dendrogram provides a good representation of the similarity matrix (r= 0.68). The drought-tolerant Eruca materials obtained in this study will be valuable for genetic improvement not only in Eruca itself, but also in Brassica crops since they are drought-tolerant lines from a drought-tolerant species. [ABSTRACT FROM PUBLISHER]

The receptor kinase CRINKLY 4 (CR4) and its orthologs are known for their essential roles in cell differentiation and their shuttling between plasma membrane and cytoplasmic vesicles, a unique feature tied to their extracellular domain. However, the extracellular regulators of CR4 have been little known. Here we identified an OsCR4 Interacting Protein 1 (OsCIP1) (also named as OsLTPL36 in rice) by a yeast two-hybrid screen using the extracellular domain of OsCR4 (OsCR4E) as bait. OsCIP1/OsLTPL36 harbors a signal peptide and is localized to the outer surface of the plasma membrane. It interacted with the TNFR subdomain of OsCR4, causing an increase in OsCR4 recycling to the plasma membrane. oscip1 , in which OsCR4 protein was decreased, exhibited thinner aleurone layer, late germination and delayed growth; while OsCIP1- overexpressing plants, in which OsCR4 protein was increased, displayed enhanced growth at the early seedling stage. OsCIP1 was cleaved between W61 and Q62, and the resulting C-terminal half exhibited a greater affinity for OsCR4E than did its precursor. Abolishing this cleavage site compromises OsCIP1′s ability to promote seedling growth. Our results provide valuable clues for the regulation of CR4 activity and its functions in aleurone layer cell differentiation by a secreted small protein in rice. • OsCIP1 interacts with the extracellular TNFR subdomain of receptor kinase OsCR4. • Cleavage of OsCIP1 may occur between amino acid W61 and Q62. • OsCIP1 promotes aleurone layer development, seed germination and early seedling growth. • OsCIP1 regulates the stability of OsCR4. [ABSTRACT FROM AUTHOR]

Water deficit is one of the most wide spread constraint to crop productivity in the world and it is of prime necessity to try to findsuitable genotype resistant to drought stress conditions.. In order to study the effect of drought stress on germination and earlyseedling growth of corn, an experiment was designed with four hybrids of corn (KSC704, KSC475, KSC500 and Consor) byusing five concentrations of PEG 6000 (0, -4, -8, -12 and -16 bar). The experiment was laid out in completely randomized designwith four replications in Seed Technology Laboratory of College of Abuoraihan, University of Tehran. Results of analysis ofvariance showed significant differences among hybrids, stress levels and its interaction for most investigated traits, whichdemonstrates high diversity among hybrids that enabled us to screen drought tolerant cultivar. To find the best tolerant hybrid todrought stress conditions, taking all traits into account in this study, we found that KSC704 is the most resistant and KSC500 isthe most sensitive hybrid

Wheat (Triticum aestivum L.) is the second most important cereal crop in India after rice. In the present study, response of wheat variety PBW-154 against three size classes and six salinity levels was assessed at germination and early seedling stages. For this, seeds of wheat variety PBW 154 were categorized into three size classes (large, medium and small) and kept under six salinity levels ( 0, 2, 4, 6, 8 and 10 g/l NaCl). Salinity stress registered the highest detrimental effects on germination percentage of medium sized seed class (83.3%), whereas small size seed class (91.7 %) experienced least ill-effects on germination percentage. The shoot length, root length and total dry weight were significantly influenced by the salinity stress. The maximum shoot length (18 cm) and root length (15.7 cm) were measured for large seed size class at controlled conditions. In general, most of the measured traits showed a significant decline at higher salinity levels suggesting that the most stress tolerant and stress avoider seed size can be explored and economically implicated in farmers' fields.

Quick seed germination and stand establishment are significant factors to lentil production under saline soil of arid and semi-arid regions. The application of beneficial nanoparticles during the seed germination has shown a new field of nano-agriculture. The current study was aimed at investigating the potential influences of nano-silicon dioxide (at 1 and 2 mM concentration) on seed germination of lentil (Lens culinaris Medik.) genotypes with different geographical origins under a range of NaCl concentrations (i.e. 0, 50, 100 and 150 mM). Results showed that germination significantly delayed by increasing salt stress. However, the rate of decline was variable among the genotypes. Application of 1 mM silicon dioxide nanoparticles (nSiO2) could considerably alleviate the adverse effect of salt stress on germination percentage, root and shoot length, seedling weight, mean germination time, seedling vigour index and cotyledon reserve mobilization. The suppressive impact with higher nSiO2 concentration (2 Mm) shows the need for cautious application of these particles during seed germination. The best performance was recorded for genotypes originated from Mexico, Syria and Jordan (PI 299127, Syrian Local Large, 78S 26013). Our results suggest that nSiO2 has favorable effect on lentil seed germination under salinity stress and it can be economic to use suitable concentration of this nanoparticle in the production system under saline conditions. [ABSTRACT FROM AUTHOR]

Investigations were carried out to study the responses of canola ( Brassica napus) under contrasting temperature regimes (day/night °C): 35/30 (high temperature) and 15/10 (low temperature) in comparison with optimal temperature (25/20) at early seedling stage. The results indicated that high temperature inhibited seedling establishment, while low temperature restrained seed germination. Both high and low temperatures showed detrimental effects on seedling growth as revealed by reduced establishment percentage, seedling vigor index, and fresh weight due to accumulated reactive oxygens. The antioxidant enzymes responded to high and low temperature differently. Under high temperature, superoxide dismutase (SOD) and peroxidase (POD) activities reduced, while catalase (CAT) activities increased. Under low temperature, however, SOD activities increased, while POD activities reduced, with CAT activities unchanged. Proline played an important role in temperature stress tolerance and can be used as an indicator for tolerance to unfavorable temperature conditions in canola seedlings. Huayouza 9 showed much stronger tolerance to both high and low temperature compared with other cultivars tested in this study. The full extent of tolerance mechanisms need to be further studied. [ABSTRACT FROM AUTHOR]

Some members of the WRKY transcription factor family are known to be involved in ABA signaling. However, it remains unclear how the WRKY transcription factors cooperate to regulate ABA signaling. In the present study, we showed that three Arabidopsis ( A. thaliana) WRKY proteins previously identified as ABA signaling regulators, WRKY18, WRKY40, and WRKY60, directly target the W-box regions in various domains of the promoters of all their own encoding genes WRKY18, WRKY40, and WRKY60, which was evidenced by chromatin immunoprecipitation and gel shift assays. Furthermore, we showed that the three WRKY proteins inhibit expression of all three WRKY genes, which was evidenced in both an in vivo assay of coexpression of the WRKY proteins with the three WRKY promoters and expression analysis of the three WRKY genes in various wrky mutants. Additionally and importantly, we provide new evidence, with three different testing systems, that WRKY18, WRKY40, and WRKY60 are negative, not positive, ABA signaling regulators, and that ABA treatment represses all three WRKY genes through a mechanism partly independent of the WRKY proteins, in which the response of the WRKY60 gene to ABA partly requires WRKY18 and WRKY40. These findings describe a mechanism of auto- and cross-repression of the WRKY transcription repressors that suggests a sophisticated mechanism to balance the negative functions of the WRKY transcription repressors in ABA signaling and helps to understand the WRKY-mediated complex events in ABA signaling pathways. [ABSTRACT FROM AUTHOR]

Abstract: This study evaluates the herbicidal potential of Peganum harmala L. (Zygophyllaceae) residues on seedling growth of Avena fatua L. (Poaceae) and Convolvulus arvensis L. (Convolvulaceae), and decomposition dynamics of its phytotoxins in the soil. Results show that among the different P. harmala plant parts used, leaves were the most toxic and caused the greatest negative effect on seedling length, seedling dry weight, leaf area and chlorophyll content of A. fatua and C. arvensis. Both weed species differed in their sensitivity to P. harmala residues. Higher reduction in plant growth parameters occurred in C. arvensis. In the presence of charcoal and depending on source of residue, receiver plants or amount of residues, the inhibitory effects of P. harmala on both test plants were eliminated or significantly reduced. Total phenolic acid content was higher in soil amended with leaf residues than that of soils with stem or root residues. Our findings revealed that a higher inhibitory effect P. harmala residues on both target species was obtained when weed seeds were sown 1 or 3 days after residue decomposition in the soil started. Total phenolic contents were maximum in the soil 1 day after decomposition, whereas phenolic amounts rapidly decreased with increasing decomposition. In conclusion, P. harmala residues had potent herbicidal activity and could be used as a natural herbicide for weed control. [Copyright &y& Elsevier]

Abstract: Soil water content at sowing is an important determinant of chickpea seed emergence and early growth. The seed emergence and seedling growth of 9 kabuli and 11 desi chickpea genotypes sown and grown under four soil moisture contents (25, 50, 75 and 100% of field capacity) was measured in a glasshouse study. Across soil moisture treatments the day of first emergence was negatively correlated to all plant growth parameters, e.g. above-ground biomass and plant height (r =−0.83 to −0.94). At 50 and 25% field capacity the onset of seed emergence was delayed, and both the number of seeds that emerged and early growth were reduced. Within the 25% soil moisture treatment, genotypes with an early emergence had a high rate of emergence (as estimated by regression against time) and produced seedlings with a high specific leaf area. Genotypic differences were observed in the number of seeds that emerged, day of first emergence, and early growth across the soil moisture treatments. Differences in final emergence were not related to chickpea type (i.e. desi or kabuli) or seed size, but the kabuli types emerged later than desi types (P <0.001). The response of early dry matter production and leaf area to soil moisture was quadratically proportional to seed size, while the plant height response was linearly proportional to seed size. As a consequence kabuli chickpeas generated a higher degree of early vigour than desi types as soil moisture increased until seed sizes become extremely large, whereas under low soil moisture, kabuli chickpeas will have a much smaller or possibly no early vigour advantage over desi types. [Copyright &y& Elsevier]

Copyright of Environmental Research, Engineering & Management / Aplinkos Tyrimai, Inžinerija ir Vadyba is the property of Institute of Environmental Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A greenhouse experiment was conducted using twelve Japonica rice genotypes differing in grain Cd concentration, to study the genotypic difference in germination and early seedling growth in response to Cd stress and its relation to Cd accumulation. The results showed that under low Cd level (0.5 mM), germination was significantly enhanced for most rice genotypes, but higher Cd levels (2.5 and 10.0 mM) inhibited germination dramatically. When exposed to 10.0 mM Cd, a few genotypes could still germinate, but the seedlings of all genotypes would die in early stage. Shoot height and dry weight, and root length and dry weight of seedling were significantly inhibited at 0.5 and 2.5 mM Cd levels, irrespectively of genotypes, and the inhibition became more severe under higher Cd level. There was a significant genotypic difference in response of germination, early seedling growth and shoot Cd concentration to Cd stress. The difference was the largest for germination, followed by root growth, the least for shoot growth. A cluster analysis of tolerance indices, including germination rate, shoot height and weight, root length and weight of the plants exposed to 2.5 mM Cd level showed that 12 rice genotypes may be grouped into three clusters, i.e. high-, intermediate- and weak Cd-tolerance. No significant correlation was found between grain Cd concentration and Cd-tolerance in terms of germination and seedling growth, and shoot Cd concentrations, suggesting that it is possible to develop rice cultivars with high Cd-tolerance and low grain Cd accumulation. [ABSTRACT FROM AUTHOR]

Reseeding of alfalfa is affected until autotoxic chemicals break down or are dispersed, often requiring a year or more. Bioassays of seed germination and early seedling growth, on agar medium in petri dishes, were conducted to evaluate autotoxic responses of 20 alfalfa germplasms to water-soluble extracts of alfalfa leaf tissue. Root length, 120 hr after placing imbibed seed on agar, was more sensitive to the autotoxin(s) than was hypocotyl length, germination speed, and final germination percentage. Path coefficient analyses showed variation in root length had 7-17 times more effect than variation in hypocotyl length in determining autotoxic effects on total seedling length. Although variations in seed size and germination rate were negatively associated (P <0.05) with final root length, the autotoxin had little effect on these factors relative to that on root length. Germplasms in the control differed (P <0.05) in root length, requiring tolerance to be evaluated as percent of control. Germplasms, as percent of control, differed significantly (P <0.05) at extract concentrations of 1.0 and 4.0 g l[SUP-1], but the range and LSD were more favorable for selection at 1.0 gl[SUP-1]. Root length is appropriate for genetic assessments of tolerance to the autotoxin when expressed as percent of control. [ABSTRACT FROM AUTHOR]

An investigation of seed germination and early seedling growth of Eucalyptus microtheca was based on seed collection from 10 widely separated provenances in Australia. Genetic variation of seed germination and early seedling growth was observed among a series of provenances whose natural habitats range from different climatic condition. In the ten provenances, both the model of seed relative germination percentage and the model of seed total germination percentage fitted Logistic regression [y=a/(1+exp(-ex+b))]. In comparison with provenances from four high temperature (mean annual maximum temperature >30.0 °C; mean annual minimum temperature >17.0 °C) areas, six low temperature (mean annual maximum temperature <30.0 °C; mean annual minimum temperature <17.0 °C) areas showed the fast germination rate and the high total germination percentage. For each provenance we have 45 seedlings equally divided into three watering levels (100%, 50%, and 25% of field capacity), and studies on relationship between early seedling growth and climatic factors of the natural habitat of provenance. In control treatment, height growth of the seedling has been associated with intrinsically the driest quarter precipitation in the seed collection areas of provenance. In all the treatments, length growth of the biggest leaf of the seedling was related to mean annual maximum temperature and mean annual minimum temperature in origin of provenance. In contrast, basal diameter growth of the seedling was related to mean annual minimum temperature of the seed collection areas in water stress treatment. From an ecological viewpoint, the fast germination rate and the high total germination percentage of the seed and rapid early growth of the seedling appear to be favourable adaptations to the climatic conditions prevailing in the natural habitat of provenance. [ABSTRACT FROM AUTHOR]