Search

With the expansion of eucalyptus crops to areas with severe water limitations, physiological studies involving eucalyptus clones to identify those that are tolerant to water stress become important. The objective of this study was to assess morphological and physiological responses by eucalyptus clones subjected to drought stress and rehydration. The experiment consisted of three eucalyptus clones: VC865, I224 and I144 and two water regimes: control and water stress followed by rehydration, with six replicates. Leaf water potential, gas exchange, maximum quantum efficiency of photosystem II and plant height and stem diameter were evaluated under drought stress and rehydration. After 6 d of rehydration, the number of leaves, leaf area and dry mass of root, leaf, stem and their total were evaluated. All clones showed intense reduction of gas exchange during the drought stress period, and only VC865 and I144 showed rapid recovery with 3 d of rehydration. Clone I224 showed greater reduction in height, stem diameter, number of leaves, water potential at midday (Ψw Midday), and maximum quantum efficiency of photosystem II (Fv/Fm). Clones VC865 and I144 showed lower reductions in Ψw Midday and Fv/Fm under stress. VC865 had lower reductions in leaf number, leaf area and higher leaf dry mass, while clone I144 had higher height and lower reduction in root dry mass under. Both these clones showed higher water use efficiency with 3 d of rehydration. These different phenotypic plasticities gave the clones VC865 and I144 efficient mechanisms of acclimatization to stress and more drought tolerance, enhancing their greater capacity for recovery after stress, which allowed lower dry mass reduction. Clone I224, however, was more susceptible to drought stress, undergoing greater physiological damage with only partial recovery during rehydration. [ABSTRACT FROM AUTHOR]

This pot experiment was conducted to evaluate the response of potato plants to different levels of salinity in terms of plant dry mass (PDM), root dry mass (RDM), plant height, number of stems and some mineral elements analysis from aerial parts of potato plants. Two potato cultivars namely, Madrid and Alver stone russet were exposed to three levels of salinity (0, 50 and 100 mM). Pots test plots were arranged in a randomized complete block design with three replications. Salt stress left significant effects on all characters, i.e., biomass and height of potato plants were decreased, but Na content was increased significantly with salt stress. As well, our results revealed positive correlation among K content and RDM in the treatment 50 mM and P content and PDM in the treatment 100 mM of salinity. On the other hand, the results revealed that increasing concentrations of salinity have negative effects on biomass and plant growth in all tested potato cultivars.

Temporal and spatial variations in ozone levels and temporal changes in solar radiation greatly influence ultraviolet radiation incidence to crops throughout their growth, yet the interactive effects of CO2 and UV-B radiation on Basil production under sunlight environmental conditions has not been studied. Basil ‘Genovese’ plants grown under sunlit plant growth chambers were subjected to a combination of supplemental UV-B (0 and 10 kJ m−2d−1) and ambient (420 ppm) and elevated (720 ppm) CO2 treatments for 38 days after 14 days of germination. UV-B radiation treatments caused a decrease in basil stem branching, fresh mass, and stem dry mass under both CO2 treatments when harvested after 17 and 38 days of treatment. There was also an increase in basil leaf surface wax under UV-B (10 kJ m−2d−1) treatment compared to controls (0 kJ m−2d−1). Elevated CO2 treatments caused a decrease in morphological features, including specific leaf area and fresh mass. Interactive effects between UV-B and CO2 treatments existed for some morphological features, including plant height, root surface area, and average root diameter. Understanding the impacts that CO2 and UV-B radiation treatments have on basilcan improve existing varieties for increased tolerance while simultaneously improving yield, plant morphology, and physiology. [ABSTRACT FROM AUTHOR]

The increase in atmospheric CO2 concentration ([CO2]) due to climate change may alter the composition of communities and the functioning of ecosystems. Owing to greater nitrogen use efficiency, leguminous plants present more effective responses to increasing [CO2] than non‐legumes. The objective of this study was to evaluate the morphophysiological and growth responses of two species from the Cerrado, a native C3 herbaceous legume (Stylosanthes capitata Vogel.) and an invasive C4 grass (Melinis minutiflora P. Beauv) growing alone or in competition, in ambient (350 ppm) and high (1000 ppm) [CO2]. Competition with S. capitata reduced leaf development and dry matter production in M. minutiflora individuals, regardless of [CO2]. Stylosanthes capitata increased root system growth under high [CO2] and competition. This change allows greater soil exploitation, decreasing nutrient limitation to S. capitata development. The leguminous species S. capitata showed advantages in the competition for resources under high [CO2] concerning the invasive grass. Although invasive C4 species are initially better in the colonisation of the invaded areas, the C3 native species of Cerrado may adjust morphophysiological traits when growing at high [CO2] and develop strategies that enable it to more effectively compete for resources. [ABSTRACT FROM AUTHOR]

The increase in atmospheric CO2 concentration ([CO2]) due to climate change may alter the composition of communities and the functioning of ecosystems. Owing to greater nitrogen use efficiency, leguminous plants present more effective responses to increasing [CO2] than non‐legumes. The objective of this study was to evaluate the morphophysiological and growth responses of two species from the Cerrado, a native C3 herbaceous legume (Stylosanthes capitata Vogel.) and an invasive C4 grass (Melinis minutiflora P. Beauv) growing alone or in competition, in ambient (350 ppm) and high (1000 ppm) [CO2]. Competition with S. capitata reduced leaf development and dry matter production in M. minutiflora individuals, regardless of [CO2]. Stylosanthes capitata increased root system growth under high [CO2] and competition. This change allows greater soil exploitation, decreasing nutrient limitation to S. capitata development. The leguminous species S. capitata showed advantages in the competition for resources under high [CO2] concerning the invasive grass. Although invasive C4 species are initially better in the colonisation of the invaded areas, the C3 native species of Cerrado may adjust morphophysiological traits when growing at high [CO2] and develop strategies that enable it to more effectively compete for resources. [ABSTRACT FROM AUTHOR]

A hydroponic system was considered to be an appropriate method for root investigations, particularly if the method can be established as a screening technique to classify differences in root traits among sugarcane lines. The aim of the research was to classify root and shoot characters of sugarcane lines grown under hydroponic conditions and to investigate their correlation with the field measurements. Hydroponic and field tests used a randomized complete block design (RCBD). Eight elite sugarcane lines were assigned as treatments. Shoot and root traits were measured at 3 months after transplanting in the hydroponic experiment, and field trial measured root length density (RLD) at 4 months after planting. Root and shoot traits under the hydroponic system showed significant differences among sugarcane lines. KK3 had a high root surface area, root volume, root length and root dry weight and TBy27-1385 demonstrated a high stem height and stem dry mass. Moreover, root dry weight, root volume and root surface area positively correlated with shoot dry mass. Positive correlation was exhibited between root traits such as dry weight of root and root length derived from hydroponic studies and RLD derived from field conditions.

This pot experiment was conducted to evaluate the response of potato plants to different levels of salinity in terms of plant dry mass (PDM), root dry mass (RDM), plant height, number of stems and some mineral elements analysis from aerial parts of potato plants. Two potato cultivars namely, Madrid and Alver stone russet were exposed to three levels of salinity (0, 50 and 100 mM). Pots test plots were arranged in a randomized complete block design with three replications. Salt stress left significant effects on all characters, i.e., biomass and height of potato plants were decreased, but Na content was increased significantly with salt stress. As well, our results revealed positive correlation among K content and RDM in the treatment 50 mM and P content and PDM in the treatment 100 mM of salinity. On the other hand, the results revealed that increasing concentrations of salinity have negative effects on biomass and plant growth in all tested potato cultivars. [ABSTRACT FROM AUTHOR]

Temporal and spatial variations in ozone levels and temporal changes in solar radiation greatly influence ultraviolet radiation incidence to crops throughout their growth, yet the interactive effects of CO2 and UV-B radiation on Basil production under sunlight environmental conditions has not been studied. Basil ‘Genovese’ plants grown under sunlit plant growth chambers were subjected to a combination of supplemental UV-B (0 and 10 kJ m−2d−1) and ambient (420 ppm) and elevated (720 ppm) CO2 treatments for 38 days after 14 days of germination. UV-B radiation treatments caused a decrease in basil stem branching, fresh mass, and stem dry mass under both CO2 treatments when harvested after 17 and 38 days of treatment. There was also an increase in basil leaf surface wax under UV-B (10 kJ m−2d−1) treatment compared to controls (0 kJ m−2d−1). Elevated CO2 treatments caused a decrease in morphological features, including specific leaf area and fresh mass. Interactive effects between UV-B and CO2 treatments existed for some morphological features, including plant height, root surface area, and average root diameter. Understanding the impacts that CO2 and UV-B radiation treatments have on basilcan improve existing varieties for increased tolerance while simultaneously improving yield, plant morphology, and physiology.

Judas tree (Cercis siliquastrum L.) is a suitable species for improving the soil nitrogen fixation and creating the natural landscape in parks and roadsides. This study was aimed to investigate the growth, development and drought resistance of Cercis seedlings by applying different irrigation periods. First, the seeds of Cercis were treated to germinate and reach to seedling phase (30 cm in height) for 90 days. Then, the seedlings were examined in a completely randomized design with four irrigation periods (4, 8, 12, and 16 days) and three replicates for 70 days. Irrigation significantly affected all morphological characters whereas stem length, root length, specific leaf area, shoot dry mass, leaf dry mass (p≤ 5%) and other characters (p≤ 1%) were different among the irrigation periods. The highest stem length, collar diameter, leaf number, leaf area, shoot dry mass, leaf dry mass, collar diameter growth, height growth and survival rate were observed in 4-day irrigation period. Seedlings with 8-day irrigation period had the greatest root volume, root dry mass and plant dry mass. This is while that, the 8-day irrigation period induced the greatest root length, specific leaf area and root/shoot ratio. The results revealed that the 4-day irrigation period was suitable for raising the Cercis seedlings; however, due to the satisfactory survival and growth, as well as the low cost and easy maintenance of seedlings, the 8-day irrigation period can be a good alternative for seedling production of this species.

A hydroponic system was considered to be an appropriate method for root investigations, particularly if the method can be established as a screening technique to classify differences in root traits among sugarcane lines. The aim of the research was to classify root and shoot characters of sugarcane lines grown under hydroponic conditions and to investigate their correlation with the field measurements. Hydroponic and field tests used a randomized complete block design (RCBD). Eight elite sugarcane lines were assigned as treatments. Shoot and root traits were measured at 3 months after transplanting in the hydroponic experiment, and field trial measured root length density (RLD) at 4 months after planting. Root and shoot traits under the hydroponic system showed significant differences among sugarcane lines. KK3 had a high root surface area, root volume, root length and root dry weight and TBy27-1385 demonstrated a high stem height and stem dry mass. Moreover, root dry weight, root volume and root surface area positively correlated with shoot dry mass. Positive correlation was exhibited between root traits such as dry weight of root and root length derived from hydroponic studies and RLD derived from field conditions. [ABSTRACT FROM AUTHOR]

Drought has significant effect on wheat production by decreasing grain yield. Phenotyping the populations is a useful tool for understanding the interactions between phenotype and genotype. 135 doubled haploid (DH) genotypes and their parental varieties Plainsman (Pl) and Cappelle Desprez (CD) were phenotyped in glasshouse under well-watered (WW) and drought-stress (DS) conditions. The response of plant height, heading time, aboveground biomass, grain yield, root dry mass harvest index (HI) under both conditions, and stress tolerance index (STI) and water consumption in WW conditions was studied. We found 20% decrease in the plant growth, 66% decrease in the aboveground biomass, and 77% decrease in the grain yield. Under WW conditions, high water consumption was not related to high yields, STI, and HI. The tolerant and the sensitive genotypes were selected. In the WW and water consumption treatment, the sensitive genotype group had better grain yield performance, but under DS, the tolerant group had higher grain yield. The average yield loss was 59% in the tolerant group compared to the WW treatment, and the sensitive yield loss was 68%. Correlation was found between the grain yield and root dry mass in the tolerant group. There was significant difference between the tolerant and sensitive groups on water consumption, as the sensitive genotypes had higher water need. We found strong positive correlation between the water consumption and the grain yield in the tolerant group. This study showed that the tolerant genotypes had improved water regulating efficiency. [ABSTRACT FROM AUTHOR]

Root biomass (diameter of roots less than 1 mm) in six Cuban forests of various types, which display significant variation in root dry mass, was studied. Root biomass can be specific for individual types of studied forests. Information on the vertical distribution of fine roots is essential in order to obtain unbiased estimates of fine root biomass. The upper 0-10 cm soil layer of both submontaneous evergreen narrow-leaved and semideciduous narrow-leaved forests contained the bulk of dry mass of live roots equal to 855 and 657 g m-2, respectively, representing 76 and 61% of fine live roots recorded in the whole investigated soil profile. Different root distribution was observed in the mangrove forests where a larger amount of live fine roots (393 and 590 g m-2) in deeper soil layers (10-25 cm), representing 57 and 65% of fine live roots recorded in the whole soil profile was found. The results showed significant differences in the vertical distribution of fine roots between mangrove and other types of tropical forest. Insights into below-ground carbon dynamics of tropical lowland and montane forests had significant implications on tropical forest carbon cycle. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Slovenica is the property of Biotechnical Faculty of the University of Ljubljana 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.)

Salt stress causes extensive losses to agricultural crops, including wheat, throughout the world and has been the focus of wide research. Though, information is scarce on the potential of ancient wheat relatives in tackling this major limiting factor. Thus, six hulled tetraploid wheat genotypes (HW) were compared to a free-threshing durum wheat genotype (FTW) under different NaCl concentrations, ranging from 0 to 150 mM, at early growth stages in a sand culture experiment. Salt stress induced significant declines in the leaf chlorophyll (Chl) a, Chl b, total Chl, and carotentoid contents; the extent of the declines was greater in FTW compared to HW. Mean leaf proline (3.6-fold) and Na (1.58-fold) concentrations and Na/K (2.48-fold) drastically increased with 150 mM of NaCl; the magnitude of the increases was greater in HW compared to FTW. While the carotenoids concentration decreased with progressive salinity both in HW and FTW, the activities of antioxidant enzymes, i.e., catalase, ascorbate peroxidase, and peroxidase were reduced in FTW, but remained unchanged in HW. The above responses to 150 mM NaCl were associated with a significant decrease in shoot dry mass of FTW and lack of significant changes in that of HW. Findings of the present study could help pave the way for further studies on physiological and molecular mechanisms of salt tolerance in these durum wheat relatives. [ABSTRACT FROM AUTHOR]

Abstract: Field experiments were conducted during 2007–2009 to study the effect of deficit irrigation practices through drip irrigation system on soil moisture distribution and root growth in cotton–maize cropping sequence. Creation of soil moisture gradient is indispensable to explore the beneficial effects of partial root zone drying (PRD) irrigation and it could be possible only through ADI practice in paired row system of drip layout, that is commonly practiced in India. In the present study, PRD and deficit irrigation (DI) concepts (creation of soil moisture gradient) were implemented through alternate deficit irrigation (ADI) at two levels of irrigation using drip system. Experimental treatments comprised of six irrigation levels (full and deficit) through drip system with surface irrigation for comparison. Maize was sown after cotton under no till condition without disturbing the raised bed and drip layout. Roots confined to the shallow depth and recorded the lowest values for both the crops under conventional drip irrigation at 100% ETc. Among the deficit irrigation treatments, mild deficit irrigation produced longer lateral roots from both the sides of the plant. Contrary to rooting depth, severe water stress affected the lateral root spread and recorded lower values than other drip irrigation treatments. Soil moisture content (SMC) was low nearer to the plant (at 30cm across the lateral) and far away (at 30cm along the lateral) from the plant, irrespective of treatments. The reduction in SMC was increased at all locations as applied water level decreased. It is concluded that alternate watering imposed through ADI at 100% ETc produced longer lateral roots with higher values for root dry mass Alternate deficit irrigation (ADI) resulted uneven distribution of soil moisture content. Among the ADI treatments, ADI at 100% had less uneven distribution than ADI at 80% ETc. [Copyright &y& Elsevier]