Cell membrane stability- an important criterion for selection of heat tolerant genotypes in wheat (Triticum aestivum L.)

Cell membrane stability, grain filling rate, grain filling duration, canopy temperature and grain yield were used to evaluate performance of 100 diverse bread wheat (Triticum aestivum L.) genotypes under timely sown and late sown heat stress conditions for two cropping season. The genotypes differed significantly for all the traits show-ing considerable variation for improvement of characters. The genotypes WH1165 had significant high grain yield (14.6* g and 11.4g) and (11.3* g and 11.4* g) followed by cell membrane stability under timely sown and heat stress conditions, respectively indicating potential tolerance against heat stress. Correlation coefficients revealed that cell membrane stability (0.451**) and (0.639**) in timely sown and in late sown conditions, respectively were the most important trait followed by grain filling rate (0.882** and 0.744**) under timely sown and late sown conditions respec-tively. Results revealed that bread wheat genotypes which had high value of cell membrane stability had high grain yield showed potential photorespiration and high grain filling rate under heat stress condition. Twenty two genotypes WH1021, WH1155, VL803, WH787, NW1014, Raj3765, HD1869, 2042, WH1124, HD2285, WH1133, HUW234, 4066, Sonak, UP2425, UP2473, PBW503, PBW373, PBW533, SGP13, HD2643 and WH789 were identified as heat tolerant genotypes based on their relative performance in yield components, grain yield and heat susceptibility indi-ces. These genotypes were found to be ideal candidates to be used in developing heat tolerant wheat varieties. Canopy temperature, membrane thermostability and grain filling rate have also shown strong correlation with grain yield. Because of this association, these traits constitute the best available ‘tool’ for genetic improvement of wheat suitable for cultivation under heat stressed environments. Thus, these could be used as indirect selection criteria for developing heat tolerant wheat genotypes that would provide sufficient yields to meet the ever increasing wheat demand

Morpho-physiological, yield, and genetic characterization of indica rice (Oryza sativa L.) genotypes for salinity and drought tolerance

The occurrence of phenotypic and genotypic diversity is the key factor in crop improvement including abiotic stress tolerance. The focal objectives of this study were to evaluate and characterize 74 tropical indica rice breeding lines for phenotypic and genotypic diversity, screening for the most devastating abiotic stresses in rice; drought and salinity at the seedling stage at morpho-physiological and molecular levels. To fulfill these objectives, five studies were conducted in pots; first two experiments aimed at assessing phenotypic and yield variability at seedling and maturity stages respectively; based on several (more than 20) root and shoot traits which exploited a wide range of variability among genotypes for measured traits. Germplasm was then screened for drought stress at two moister regimes, 50%, and 100% moisture levels, under mini-hoop structures. Nine percent of the genotypes exhibited a high tolerance to drought stress, and genotypes IR86638 and IR49830 were identified as the most and least drought tolerant respectively. Germplasm was also screened for salinity tolerance in pure sand pot-culture (a simple, efficient and alternate screening method) at three levels; high salt stress (EC 12 dSm-1), moderate salt stress (EC 6 dSm-1), and control imposed one week after emergence. Thirteen genotypes (17.57%) were identified as highly salt tolerant; genotypes FED 473 and IR85427 were highly salt tolerant and salt sensitive, respectively. Root traits were found more crucial and best descriptors in identifying both salinity and drought tolerant genotypes. Genotypes were further used in Genome-wide Association Study (GWAS) to uncover important SNPs, QTLs or genes related to salinity tolerance. A higher number of significant SNPs were discovered for root traits, indicting the importance of root traits in identifying abiotic stress tolerance in rice. The knowledge gained from this investigation could be useful in breeding for better crop establishment, yield improvement, screening for any abiotic stress tolerance

A review of research on the effects of drought and temperature stress and increased CO2 on Theobroma cacao L., and the role of genetic diversity to address climate change

The global status of research on the effects of drought, temperature and elevated carbon dioxide (CO2) levels on the cacao plant, and the role of genetic diversity in producing more resilient cacao, are presented in this report. With the aim to enhance what we know about the resilience of cacao to climate change, and generate a comprehensive understanding of the questions that remain, this report highlights significant advances in published and ongoing research on drought and temperature tolerance in cacao. Most of the information about ongoing or unpublished work was obtained from personal communications and surveys involving research institutes around the globe. Organizations were selected to participate in the survey based on their presence in the relevant literature, referrals from other organizations, or personal communications from individuals attesting to their involvement in research related to drought and temperature tolerance, or increased CO2 response, in cacao. A vast network of public and private sector partners including research institutes, producer organizations, and industry representatives around the world participated and were involved to collect additional information on unpublished and on-going research work in this area. Over a 100 scientists from 50 institutes across 29 countries participated. Additional information was gathered from personal communications, surveys carried out in collaboration with WCF and its USAID-supported Feed the Future Partnership for the Climate-Smart Cocoa Program, the Global Network for Cacao Genetic Resources (CacaoNet), the International Network for Cacao Genetic Improvement (INGENIC), the Regional Breeders Working Groups, and the research team on cacao and climate change at the University of Reading, UK. Fundamentally, the literature compiled in this report serves as a basis to understand the questions that still remain regarding cacao’s responses to abiotic stresses, highlight the resources that are available to answer them, and identify synergies and complementarities. The report also helps to identify key research questions and partners for the development of a proposal for an international/multi-institutional research programme, to be implemented over the next three to five years, as part of the Collaborative Framework for Cacao Evaluation (CFCE). Although future climatic predictions are worrisome, the genetic materials held within national and international collections offer much potential in the development of improved planting material. The objective of the report is to gather as much information as possible, so that we can aim to maximize the resilience of cacao through the discovery and use of improved planting material, in combination with improved management practices.  We express our gratitude to all of those who provided details of their research on cacao genetic resources and abiotic stress and we acknowledge financial support of WCF and its Feed the Future Partnership for Climate Smart Cocoa, through a grant to Bioversity International from USDA-FAS, the ECA/CAOBISCO/FCC Joint Working Group on Cocoa Quality and Productivity; and the CGIAR Research Program on Forests, Trees and Agroforestry (FTA)

Genome-wide association analysis for heat tolerance at flowering detected a large set of genes involved in adaptation to thermal and other stresses

Fertilization sensitivity to heat in rice is a major issue within climate change scenarios in the tropics. A panel of 167 indica landraces and improved varieties was phenotyped for spikelet sterility (SPKST) under 38°C during anthesis and for several secondary traits potentially affecting panicle micro-climate and thus the fertilization process. The panel was genotyped with an average density of one marker per 29 kb using genotyping by sequencing. Genome-wide association analyses (GWAS) were conducted using three methods based on single marker regression, haplotype regression and simultaneous fitting of all markers, respectively. Fourteen loci significantly associated with SPKST under at least two GWAS methods were detected. A large number of associations was also detected for the secondary traits. Analysis of co-localization of SPKST associated loci with QTLs detected in progenies of bi-parental crosses reported in the literature allowed to narrow -down the position of eight of those QTLs, including the most documented one, qHTSF4.1. Gene families underlying loci associated with SPKST corresponded to functions ranging from sensing abiotic stresses and regulating plant response, such as wall-associated kinases and heat shock proteins, to cell division and gametophyte development. Analysis of diversity at the vicinity of loci associated with SPKST within the rice three thousand genomes, revealed widespread distribution of the favourable alleles across O. sativa genetic groups. However, few accessions assembled the favourable alleles at all loci. Effective donors included the heat tolerant variety N22 and some Indian and Taiwanese varieties. These results provide a basis for breeding for heat tolerance during anthesis and for functional validation of major loci governing this trait. (Résumé d'auteur

Evaluation of rice (Oryza sativa L.) genotypes grown under combined salinity and submergence stresses based on vegetative stage phenotyping

Sixteen rice genotypes were screened against combined salinity and submergence stresses to find out potential salt-submergence tolerant genotypes. Rice seedlings were subjected to submergence stress including two salinity levels viz., EC-6 dSm-1 and EC-8 dSm-1 for 10 days. Imposition of combined stress considerably decreased the growth parameters in rice seedlings, however ACM-18, ACM-35, and RC-251 demonstrated the maximum value for growth attributes such as leaf live (%), root and shoot length, plant fresh and dry biomass. The results of correlation and regression revealed a significant and negative association of leaf lives (%), root length, fresh weight of root and shoot, and root dry weight with mean tolerance score under combined stress indicating their importance as the useful descriptors for the selection. Euclidean clustering was categorized the rice genotypes into three major clusters, i.e., A-susceptible, B-tolerant and moderately tolerant, and C-highly tolerant. Results of cluster analysis showed that the highly tolerant genotypes namely ACM-18, ACM-35, and RC-251 were placed in the same cluster. Similar results were further confirmed by principal component analysis having the highly tolerant genotypes in the same group. Combining the morphological and multivariate analysis, ACM-18, ACM-35, and RC-251 were selected as promising genotypes for developing high-yielding salt-submergence tolerant rice

Physiological and Molecular Responses of Diverse Rice Genotypes under Drought Stress

Climate change-induced drought stress is a significant constraint on global rice (Oryza sativa L.) production, threatening food security. This study evaluated the drought resilience of 15 diverse rice genotypes from the USDA mini-core collection under field, greenhouse, and osmotic stress conditions. Field trials assessed reproductive-stage drought tolerance based on panicle length (PL), number of spikelets per panicle (NSP), and spikelet sterility (SS). Greenhouse experiments examined moisture retention at the vegetative stage. Significant genotypic variation was observed, with genotypes 310724, 310779, 311181, 311603, 311793, and Vandana exhibiting drought tolerance through stable PL and SS. Additionally, genotypes 310100, 310428, 311255, N22, and Bengal demonstrated superior moisture retention. The study emphasizes selecting genotypes with stable performance to enhance drought tolerance, with 310779 and N22 standing out for their low spikelet sterility and strong drought resilience. In contrast, genotypes like 311111, 311140, 311180, and KB showed heightened sensitivity to drought, with reduced panicle length, fewer spikelets, and increased sterility, making them less suitable for drought-prone environments. Under polyethylene glycol (PEG)-induced osmotic stress, Vandana, 301418, and 311140 exhibited strong tolerance, while 310428, 310724, 311111, 311180, 310779, and 311181 were sensitive. Drought-resistant genotypes exhibited increased root traits, including root length (RL), root-to-shoot ratio (RSR), total root number (TRN), and dry root weight (DRN). Further, drought-resistant genotypes Vandana, N22, 311255 and 311181 displayed an ABA-sensitive phenotype at early growth stages, with ABA-mediated signaling influencing osmotic stress tolerance. RT-qPCR analysis revealed increased ZIP gene expression in drought-tolerant genotypes following ABA application. These findings underscore the importance of stress-specific evaluations in identifying drought-tolerant genotypes. However, genotypes such as Vandana, N22, and 311255 emerged as promising candidates for breeding programs aimed at improving drought resilience in rice. The study provides valuable insights for developing climate-resilient rice varieties, integrating physiological, morphological, and genetic approaches to enhance adaptation to water-limited conditions. Keywords: Drought tolerance, Oryza sativa, spikelet sterility, ABA signaling, ZIP gene, root phenotyping, PEG stress

Delivering new sorghum and finger millet innovations for food security and improving livelihoods in Eastern Africa

ILRI works with partners worldwide to help poor people keep their farm animals alive and productive, increase and sustain their livestock and farm productivity, and find profitable markets for their animal products. ILRI’s headquarters are in Nairobi, Kenya; we have a principal campus in Addis Ababa, Ethiopia, and 14 offices in other regions of Africa and Asia. ILRI is part of the Consultative Group on International Agricultural Research (www.cgiar.org), which works to reduce hunger, poverty and environmental degradation in developing countries by generating and sharing relevant agricultural knowledge, technologies and policies

Photosynthetic Traits of Rice Landraces (Oryza sativa L.) Under Drought Condition

Drought stress is mainly a serious limiting factor for rice production, which creates huge economic losses by becoming more serious issue with respect to global climate change. In the view of the current situations and forecasted global food demand, it is necessary to enhance the crop productivity on the drought prone rain fed lands with utmost priority.Rice is a main staple cereal crop in the world.Climate change mainly alters the plant phyllosphere and its resource allocations. The main aim of this experiment was to evaluate the “Photosynthetic attributes on drought tolerance of rice landraces” (Oryzasativa L.). A laboratory screening, hydroponic studies and pot culture experiments were conducted in the Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, during 2020-2021 to investigate the Photosynthetic attributes. Rice land races, namely Anna(R) 4, 337- IC116006, 224 - IC463809 were studied. The present findings showed that drought stress reduced the photosynthetic parameters and enhanced the chlorophyll index and soil temperature in all the land races. Among the land races, Anna(R) 4 performed better under drought stress conditions when compared to other

Heat stress tolerance in maize - An overview

Maize (Zea mays L.), one of the world’s most important staple crops, is increasingly vulnerable to rising temperatures and erratic climatic conditions. Among various abiotic stressors, heat stress stands out as a critical factor that disrupts the crop’s growth by impairing morphological, physiological, biochemical and molecular processes ultimately leading to substantial yield losses. The severity of this issue is expected to escalate with the intensification of global warming and water scarcity. To ensure sustainable maize production, there is an urgent need to develop heat-resilient, high-yielding hybrids. This review explores recent advances in identifying thermotolerant donor lines and employing them in hybrid development. Emphasis is placed on integrated strategies, including advanced agronomic interventions, molecular breeding, CRISPR/Cas-based genome editing and the application of multi-omics platforms transcriptomics, proteomics, metabolomics and phenomics to decipher heat-responsive mechanisms. Furthermore, the integration of high-throughput phenotyping, machine learning and climate-smart agricultural practices offers promising pathways to accelerate breeding efficiency and improve field-level adaptation. By synthesizing these cutting-edge approaches, this review provides a comprehensive framework to mitigate the adverse impacts of heat stress and support climate-resilient maize cultivation in the face of future challenges