Search

Climatic conditions significantly affect the maize productivity. Among abiotic factors, nitrogen (N) fertilizer and temperature are the two important factors which dominantly affect the maize (Zea mays L.) production during the early crop growth stages. Two experiments were conducted to determine the impact of N fertilizer and temperature on the maize growth and yield. In the first experiment, the maize hybrids were screened for their sensitivity to temperature variations. The screening was based on the growth performance of the hybrids under three temperatures (T1 = ambient open-air temperature, T2 = 1°C higher than the ambient temperature, and T3 = 1°C lower than the ambient temperature) range. The results showed that an increase in temperature was resulted less 50% emergence and mean emergence (4.1 and 6.3 days, respectively), while emergence energy and full emergence were higher (25.4 and 75.2%, respectively) under the higher temperature exposure. The results showed that Syngenta 7720 and Muqabla S 25W87 were temperature tolerant and sensitive maize hybrids, respectively. The second experiment was carried out to study the response of the two selected maize hybrids (Syngenta 7720 and Muqabla S 25W87) to four N fertilizer applications. The results revealed that the maximum N use efficiency (19.5 kg kg−1) was achieved in maize hybrids with low N application (75 kg N ha−1 equivalent to 1.13 g N plant−1). However, the maximum maize grain yield (86.4 g plant−1), dry weight (203 g plant−1), and grain protein content (15.0%) were observed in maize hybrids that were grown with the application of 300 kg N ha−1 (equivalent to 4.52 g N plant−1). Therefore, it is recommended that the application of 300 kg N ha−1 to temperature tolerant maize hybrid may be considered best agricultural management practices for obtaining optimum maize grain yield under present changing climate.

Levels of arsenic (As), chromium (Cr), and copper (Cu) are increasing in the soils worldwide. Such contaminants cause toxicity in the plant systems which adversely affects growth and productivity. The objective of the present investigation was to elucidate individual and combined effects of As, Cr, and Cu (100 μM each) stress in metal hyper-accumulator plant Indian mustard (Brassica juncea L.), exposed for a week. The highest accumulation was in the roots and in decreasing order viz. Cu > As > Cr. The magnitude of oxidative stress was maximal in combined stress, followed by As, Cr, and then Cu stress. Glutathione in conjunction with glutathione reductase, glutathione peroxidase, and glutathione S-transferase increased in all set of stress treatments, notably when exposed to Cr alone. In addition, the level of sulfur-rich compounds like cysteine, phytochelatins, and non-protein thiols increased under each stress indicating efficient coupling of the enzyme system and sulfur-containing compounds during stress conditions. The highest tolerance or growth index of plants was recorded for Cu. Protein profiling of leaf tissues showed modulation of protein patterns in each stress. Mediator of RNA polymerase II transcription subunit 1 isoform X1, RuBisCO (large subunit), and ribosomal protein S3 proteins were more abundant under Cr and Cu stress. Zinc finger A20/AN1 domain-containing stress-associated protein 5–like protein was more abundant under Cu stress. HSP (15.7 kDa) and autophagy protein 5–like were in higher abundance under As and combined stress. Our results suggest that Indian mustard has a differential mode of defense against a particular stressor at the level of protein expression profile.

Arsenic (As) is a toxic ubiquitous metalloid. Exposure of plants to As can result in various morphological, physiological and biochemical variations. Hydroponic experiment was conducted to study the growth response, lipid peroxidation, proline and antioxidant defence system under arsenic (As) stress in the cowpea. Ten day old seedlings of cowpea grown hydroponically, were treated with 0, 25, 50, 75 and 100 µM (Na2HAsO4) sodium arsenate for 7 days and analysed for morphological and biochemical traits under As stress. Significant decline in plant root and shoot length along with biomass was recorded with increased arsenic doses, as compared to control. The As treatment resulted in increased proline and decrease in malondialdehyde (MDA) content in seedlings of cowpea with increased concentration. Enzymatic antioxidants like catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) showed increased activity in dose dependant manner over control under As stress. Results indicated lower content of MDA and enhanced activities of the enzymatic antioxidant perform a significant role in As tolerance in cowpea.

The present study was conducted to evaluate the differences in photosynthetic parameters and antioxidant enzyme activity among two genotypes of soybean (Glycine max L.) in response to salinity stress. Ten-day-old seedlings, grown hydroponically, were treated with 0, 25, 50, 75, 100, 125 and 150 mM NaCl for 7 days and analysed for the traits as biomarkers for identification of salt-tolerant soybean genotype. It was observed that NaCl stress caused severe impairments in photosynthetic rate, chlorophyll fluorescence and chlorophyll content in both the genotypes, but the damage were much more pronounced in salt-sensitive genotype VL SOYA-47. Moreover, chlorophyll fluorescence measurements showed higher non-photochemical quenching in genotype VL SOYA-47 and lower in genotype VL SOYA-21. The antioxidant enzyme activities (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) was observed much higher in VL SOYA-21 than in VL SOYA-47 at various levels of NaCl treatments. From the results, it could be suggested that VL SOYA-21 is the salt tolerant and VL SOYA-47 is a salt sensitive soybean genotype. The tolerance capacity of VL SOYA-21 against NaCl stress can be related with the ability of this genotype in possessing vital photosynthetic system and ROS scavenging capacity.

Soybean, the worldwide main source of oil and high protein feeds for the livestock sector has a high cadmium (Cd) accumulation capacity. With this background, the hydroponic culture experiments were conducted to investigate the effects of different concentrations of Cd (0-100 µM) on growth, water relations, photosynthetic variables, oxidative stress, and antioxidant response in two soybean genotypes P-218 and P-898. Ten days old seedlings were subjected to (0-100 µM CdCl2) for 15 days. The results indicated that the growth of genotype P-218 was not affected significantly upto 75 µM CdCl2 treatment growth of P-828 was reduced significantly beyond 25 µM CdCl2 treatments. Cd toxicity caused severe impairments in photosynthetic variables like photosynthetic rate, chlorophyll fluorescence and chlorophyll content, in P-898 than in P-218. The activities of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) were higher in P-218 than in P-828 at various levels of Cd treatments. Chlorophyll fluorescence measurements revealed that non-photochemical quenching increased in P-218 and decreased in P-828 whereas the electron transport rate increased under Cd stress in P-828 and decreased in P-218. It is concluded that tolerance capacity of P-218 against Cd can be associated with the capability of this genotype in keeping an active photosynthetic system and strong antioxidant defense system.

Ten genotypes of wheat (Triticum aestivum L.) were grown for 20 days in complete nutrient solution with 1 mM (nitrogen-insufficient), 4 mM (nitrogen-moderate) and 10 mM (nitrogen-sufficient) nitrogen (N) levels, and nitrogen efficiency (NE) was analyzed. Of these 10 genotypes, VL829 was identified as the most N-efficient, while HUW234 the most N-inefficient. To find out the physiological basis of this difference, we investigated the possible role of influx across the root cell plasma membrane in conferring NE by measuring the short-term uptake in selected 10 genotypes. Uptake experiments revealed the presence of two separate nitrate transporter systems mediating high- and low-affinity nitrate uptake. Interestingly, the nitrate uptake by the roots of VL829 is mediated by both high- and low-affinity nitrate transporter systems, while that of HUW234 by only low affinity nitrate transporter system. The study suggests that root uptake rate may play an important role in conferring N- efficiency of whea...

The present investigation was conducted to evaluate salt tolerance in nine genotypes of soybean (Glycine max L.). Ten-day-old seedlings, grown hydroponically, were treated with 0, 25, 50, 75, 100, 125 and 150 mM NaCl for five days. Growth, lipid peroxidation and antioxidant enzyme activities were evaluated. Growth, measured in terms of length, fresh weight and dry weight of plants, was drastically reduced in PK-416, while there was little effect of NaCl treatment on Pusa-37 genotype of soybean. A high level of lipid peroxidation was observed in PK-416 as indicated by increased level of malondialdehyde. Activities of superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase were maximum in Pusa-37 where 9-fold, 1-fold, 5-fold and 6-fold increases over control were observed, respectively. The results suggested that PK-416 and Pusa-37 are salt-sensitive and salt-tolerant genotypes of soybean, respectively, and antioxidant defence systems involved in conferring the sensitiveness ...

26 páginas, 6 figuras, 7 tablas., [Background]: The combination of high-throughput transcript profiling and next-generation sequencing technologies is a prerequisite for genome-wide comprehensive transcriptome analysis. Our recent innovation of deepSuperSAGE is based on an advanced SuperSAGE protocol and its combination with massively parallel pyrosequencing on Roche’s 454 sequencing platform. As a demonstration of the power of this combination, we have chosen the salt stress transcriptomes of roots and nodules of the third most important legume crop chickpea (Cicer arietinum L.). While our report is more technology-oriented, it nevertheless addresses a major world-wide problem for crops generally: high salinity. Together with low temperatures and water stress, high salinity is responsible for crop losses of millions of tons of various legume (and other) crops. Continuously deteriorating environmental conditions will combine with salinity stress to further compromise crop yields. As a good example for such stress-exposed crop plants, we started to characterize salt stress responses of chickpeas on the transcriptome level. [Results]: We used deepSuperSAGE to detect early global transcriptome changes in salt-stressed chickpea. The salt stress responses of 86,919 transcripts representing 17,918 unique 26 bp deepSuperSAGE tags (UniTags) from roots of the salt-tolerant variety INRAT-93 two hours after treatment with 25 mM NaCl were characterized. Additionally, the expression of 57,281 transcripts representing 13,115 UniTags was monitored in nodules of the same plants. From a total of 144,200 analyzed 26 bp tags in roots and nodules together, 21,401 unique transcripts were identified. Of these, only 363 and 106 specific transcripts, respectively, were commonly up- or down-regulated (>3.0-fold) under salt stress in both organs, witnessing a differential organ-specific response to stress. Profiting from recent pioneer works on massive cDNA sequencing in chickpea, more than 9,400 UniTags were able to be linked to UniProt entries. Additionally, gene ontology (GO) categories over-representation analysis enabled to filter out enriched biological processes among the differentially expressed UniTags. Subsequently, the gathered information was further cross-checked with stress-related pathways. From several filtered pathways, here we focus exemplarily on transcripts associated with the generation and scavenging of reactive oxygen species (ROS), as well as on transcripts involved in Na+ homeostasis. Although both processes are already very well characterized in other plants, the information generated in the present work is of high value. Information on expression profiles and sequence similarity for several hundreds of transcripts of potential interest is now available. [Conclusions]: This report demonstrates, that the combination of the high-throughput transcriptome profiling technology SuperSAGE with one of the next-generation sequencing platforms allows deep insights into the first molecular reactions of a plant exposed to salinity. Cross validation with recent reports enriched the information about the salt stress dynamics of more than 9,000 chickpea ESTs, and enlarged their pool of alternative transcripts isoforms. As an example for the high resolution of the employed technology that we coin deepSuperSAGE, we demonstrate that ROS-scavenging and -generating pathways undergo strong global transcriptome changes in chickpea roots and nodules already 2 hours after onset of moderate salt stress (25 mM NaCl). Additionally, a set of more than 15 candidate transcripts are proposed to be potential components of the salt overly sensitive (SOS) pathway in chickpea. Newly identified transcript isoforms are potential targets for breeding novel cultivars with high salinity tolerance. We demonstrate that these targets can be integrated into breeding schemes by micro-arrays and RT-PCR assays downstream of the generation of 26 bp tags by SuperSAGE, Work of the authors was supported by a grant from the Aquarhiz project (INCOCT- 2004-509115) to GK, grants from the Grain Legumes project (Food-CT- 2004-506223) to GK and GenXPro GmbH, and from DFG to GK (Ka 332/22-1).