The present study was carried out in a greenhouse to evaluate the positive effect of foliar application of glycine betaine (10mM), grain presoaking in salicylic acid (0.05 M) and their interaction on drought tolerance of two wheat (Triticum aestivum L.) cultivars (sensitive, Sakha 94 and tolerant, Sakha 93). Exogenous application of glycine betaine (GB), salicylic acid (SA) or their interaction could counteract the adverse effects of drought by improvement of growth vigor of root and shoot, leaf area, retention of pigment content, increasing the concentration of organic solutes (soluble sugars and soluble nitrogen) as osmoprotectants, keeping out the polysaccharides concentration and/or stabilization of essential proteins in both wheat cultivars. Grain presoaking in SA or foliar application with GB alleviated the stress imposed by drought by keeping water within leaves and consequently recover the turgidity of stressed plants particularly the sensitive ones. Furthermore, the effect was more pronounced with GB+SA treatment. The applied chemicals appeared to alleviate the effect of water stress on wheat yield and the biochemical aspects of yielded grains.
Salinity and water stress limit crop productivity worldwide and generate substantial economic losses each year, yet innovative research on crop and natural resource management can reveal cost-effective ways in which farmers can increase both their productivity and their income. Presenting recent research findings on salt stress, water stress and stress-adapted plants, this book offers insights into new strategies for increasing the efficiency of crops under stressful environments. The strategies are based on conventional breeding and advanced molecular techniques used by plant physiologists, and are discussed using specific case studies to illustrate their potential. The book emphasizes the effects of environmental factors on specific stages of plant development, and discusses the role of plant growth regulators, nutrients, osmoprotectants and antioxidants in counteracting their adverse affects. Synthesising updated information on mechansisms of stress tolerance at cell, tissue and whole-plant level, this book provides a useful reference text for post graduate students and researchers involved in the fields of stress physiology and plant physiology in general, with additional readership amongst researchers in horticulture, agronomy, crop science, conservation, environmental management and ecological restoration.
This book presents recent advances in global wheat crop research, including the effects of abiotic stresses like high and low temperatures, drought, hypoxia, salinity, heavy metals, nutrient deficiency, and toxicity on wheat production. It also highlights various approaches to alleviate the damaging effects of abiotic stress on wheat as well as advanced approaches to develop abiotic-stress-tolerant wheat crops. Wheat is probably one of the world’s most important cereals; it is a staple food in more than 40 countries, and because of its adaptability is cultivated in almost every region. Global wheat production has more than doubled in the last 50 years due to higher yields. However, despite their high yield potential, modern wheat cultivars are often subject to crop loss due to the abiotic stresses. As such, plant breeders have long aimed to improve tolerance in order to maintain yield. Written by 85 experts, and offering the latest insights into wheat responses and tolerance to various abiotic stresses, it is a valuable tool for agronomists, plant breeders, plant physiologists and students in the field of plant science and agriculture. It is the first book to comprehensively cover past and current abiotic stress problems and tolerance mechanisms.
Heat and drought are the major abiotic factors that limit wheat production worldwide. Wheat is one of the important staple crops, so, the production decline due to these factors faces a major challenge in addressing food security. Grain filling in wheat occurs when the temperature is rising, and soil moisture is declining in most wheat growing environment, so there is high demand in breeding wheat for post anthesis heat and drought stress tolerance. However, limited genetic variability in wheat cultivars possess a challenge. The objective of the first study was to screen wild emmer wheat (Triticum dicoccoides) for post anthesis heat tolerance and measure physiological traits and yield trait associated with the tolerance. Twenty-one accessions of Triticum dicoccoides and four check varieties were screened at optimum temperature (25/19 °C day/night) and high temperature (35/29 °C day/night). High temperature decreased flag leaf survival duration, chlorophyll content, and chlorophyll fluorescence more in the wild accessions than in the checks. A few wild accessions were found to be heat tolerant based on the lower heat susceptibility index (HSI) value in seed weight. Therefore, there is a potential for utilizing this genetic variability from the accessions to improve post anthesis heat tolerance in wheat. The maintenance in seed weight might be coming from the mobilization of stored reserve in the stem. The stem reserves are commonly called water-soluble carbohydrates (WSC). WSC accumulated during the vegetative stage, pre-flowering, or right after flowering can be mobilized to assist grain filling when assimilate supply is limited under stress. The second chapter is about the physiological and genetic basis of water-soluble carbohydrates (WSC) concentration during mid- grainfilling stage in wheat. We evaluated 400 diverse winter wheat breeding lines and 30 released varieties in different environments ranging from irrigated to rainfed for WSC concentration. WSC concentration was significantly and positively correlated with the seed weight, whereas the height was mostly negatively correlated, and we didn't see any relation with heading date. Less decline in grain yield under simulated terminal drought stress was observed in varieties with high WSC content. Further, we identified six significant SNP markers in 7D region significantly associated with the WSC concentration, and each marker explained 4-5% of the variation. On running several genomic selection prediction models on WSC using ridge regression, partial least squares, elastic net, and random forest models and different training population sizes (20%, 40%, 60%, and 80%), the prediction accuracy increased from 0.2 to 0.6. The accuracy increased as a large amount of data was available to train the model, and overall the highest accuracy was observed with the random forest and average of all four models. The accuracy can be further increased with the inclusion of a large number of samples, and multi- year and location testing on WSC. Higher genetic variation, high heritability, and significant positive relation with seed weight make WSC an important trait for selection under post anthesis drought. In the third study, aerial phenotyping using UAV with a multispectral camera was used to capture the images in three different wave bands: red, green, and near infrared. Normalized Difference Vegetative Index (NDVI) was calculated from red and near infrared bands. NDVI calculated from the aerial imaging during reproductive stages were more correlated with the grain yield than a visual screening of percentage greenness. NDVI measurement during grain filling had the highest significant correlation and explained more than 50% variation in the yield. Lodging was another factor impacting yield explaining about 60% variability in yield. With its wide applicability, aerial phenotyping has the potential for assisting breeders in selecting diverse genotypes and can outperform visual selection.
This volume will be the only existing single-authored book offering a science-based breeder’s manual directed at breeding for water-limited environments. Plant breeding is characterized by the need to integrate information from diverse disciplines towards the development and delivery of a product defines as a new cultivar. Conventional breeding draws information from disciplines such as genetics, plant physiology, plant pathology, entomology, food technology and statistics. Plant breeding for water-limited environments and the development of drought resistant crop cultivars is considered as one of the more difficult areas in plant breeding while at the same time it is becoming a very pressing issue. This volume is unique and timely in that it develops realistic solutions and protocols towards the breeding of drought resistant cultivars by integrating knowledge from environmental science, plant physiology, genetics and molecular biology.
This book focuses on early germination, one of maize germplasm most important strategies for adapting to drought-induced stress. Some genotypes have the ability to adapt by either reducing water losses or by increasing water uptake. Drought tolerance is also an adaptive strategy that enables crop plants to maintain their normal physiological processes and deliver higher economical yield despite drought stress. Several processes are involved in conferring drought tolerance in maize: the accumulation of osmolytes or antioxidants, plant growth regulators, stress proteins and water channel proteins, transcription factors and signal transduction pathways. Drought is one of the most detrimental forms of abiotic stress around the world and seriously limits the productivity of agricultural crops. Maize, one of the leading cereal crops in the world, is sensitive to drought stress. Maize harvests are affected by drought stress at different growth stages in different regions. Numerous events in the life of maize crops can be affected by drought stress: germination potential, seedling growth, seedling stand establishment, overall growth and development, pollen and silk development, anthesis silking interval, pollination, and embryo, endosperm and kernel development. Though every maize genotype has the ability to avoid or withstand drought stress, there is a concrete need to improve the level of adaptability to drought stress to address the global issue of food security. The most common biological strategies for improving drought stress resistance include screening available maize germplasm for drought tolerance, conventional breeding strategies, and marker-assisted and genomic-assisted breeding and development of transgenic maize. As a comprehensive understanding of the effects of drought stress, adaptive strategies and potential breeding tools is the prerequisite for any sound breeding plan, this brief addresses these aspects.
Drought is one of the most severe constraints to crop productivity worldwide, and thus it has become a major concern for global food security. Due to an increasing world population, droughts could lead to serious food shortages by 2050. The situation may worsen due to predicated climatic changes that may increase the frequency, duration and severity of droughts. Hence, there is an urgent need to improve our understanding of the complex mechanisms associated with drought tolerance and to develop modern crop varieties that are more resilient to drought. Identification of the genes responsible for drought tolerance in plants will contribute to our understanding of the molecular mechanisms that could enable crop plants to respond to drought. The discovery of novel drought related genes, the analysis of their expression patterns in response to drought, and determination of the functions these genes play in drought adaptation will provide a base to develop effective strategies to enhance the drought tolerance of crop plants. Plant breeding efforts to increase crop yields in dry environments have been slow to date mainly due to our poor understanding of the molecular and genetic mechanisms involved in how plants respond to drought. In addition, when it comes to combining favourable alleles, there are practical obstacles to developing superior high yielding genotypes fit for drought prone environments. Drought Tolerance in Plants, Vol 2: Molecular and Genetic Perspectives combines novel topical findings, regarding the major molecular and genetic events associated with drought tolerance, with contemporary crop improvement approaches. This volume is unique as it makes available for its readers not only extensive reports of existing facts and data, but also practical knowledge and overviews of state-of-the-art technologies, across the biological fields, from plant breeding using classical and molecular genetic information, to the modern omic technologies, that are now being used in drought tolerance research to breed drought-related traits into modern crop varieties. This book is useful for teachers and researchers in the fields of plant breeding, molecular biology and biotechnology.
A close examination of current research on abiotic stresses in various plant species The unpredictable environmental stress conditions associated with climate change are significant challenges to global food security, crop productivity, and agricultural sustainability. Rapid population growth and diminishing resources necessitate the development of crops that can adapt to environmental extremities. Although significant advancements have been made in developing plants through improved crop breeding practices and genetic manipulation, further research is necessary to understand how genes and metabolites for stress tolerance are modulated, and how cross-talk and regulators can be tuned to achieve stress tolerance. Molecular Plant Abiotic Stress: Biology and Biotechnology is an extensive investigation of the various forms of abiotic stresses encountered in plants, and susceptibility or tolerance mechanisms found in different plant species. In-depth examination of morphological, anatomical, biochemical, molecular and gene expression levels enables plant scientists to identify the different pathways and signaling cascades involved in stress response. This timely book: Covers a wide range of abiotic stresses in multiple plant species Provides researchers and scientists with transgenic strategies to overcome stress tolerances in several plant species Compiles the most recent research and up-to-date data on stress tolerance Examines both selective breeding and genetic engineering approaches to improving plant stress tolerances Written and edited by prominent scientists and researchers from across the globe Molecular Plant Abiotic Stress: Biology and Biotechnology is a valuable source of information for students, academics, scientists, researchers, and industry professionals in fields including agriculture, botany, molecular biology, biochemistry and biotechnology, and plant physiology.
Abiotic stress adversely affects crop production worldwide, decreasing average yields for most of the crops to 50%. Among various abiotic stresses affecting agricultural production, drought stress is considered to be the main source of yield reduction around the globe. Due to an increasing world population, drought stress will lead to a serious food shortage by 2050. The situation may become worse due to predicated global climate change that may multiply the frequency and duration and severity of such abiotic stresses. Hence, there is an urgent need to improve our understanding on complex mechanisms of drought stress tolerance and to develop modern varieties that are more resilient to drought stress. Identification of the potential novel genes responsible for drought tolerance in crop plants will contribute to understanding the molecular mechanism of crop responses to drought stress. The discovery of novel genes, the analysis of their expression patterns in response to drought stress, and the determination of their potential functions in drought stress adaptation will provide the basis of effective engineering strategies to enhance crop drought stress tolerance. Although the in-depth water stress tolerance mechanisms is still unclear, it can be to some extent explained on the basis of ion homeostasis mediated by stress adaptation effectors, toxic radical scavenging, osmolyte biosynthesis, water transport, and long distance signaling response coordination. Importantly, complete elucidation of the physiological, biochemical, and molecular mechanisms for drought stress, perception, transduction, and tolerance is still a challenge to the plant biologists. The findings presented in volume 1 call attention to the physiological and biochemical modalities of drought stress that influence crop productivity, whereas volume 2 summarizes our current understanding on the molecular and genetic mechanisms of drought stress resistance in plants.
