Data analysis methods.

Climate change is a major threat to most of the agricultural crops grown in tropical and sub-tropical areas globally. Drought stress is one of the consequences of climate change that has a negative impact on crop growth and yield. In the past, many simulation models were proposed to predict climate change and drought occurrences, and it is extremely important to improve essential crops to meet the challenges of drought stress which limits crop productivity and production. Wheat and barley are among the most common and widely used crops due to their economic and social values. Many parts of the world depend on these two crops for food and feed, and both crops are vulnerable to drought stress. Improving drought stress tolerance is a very challenging task for wheat and barley researchers and more research is needed to better understand this stress. The progress made in understanding drought tolerance is due to advances in three main research areas: physiology, breeding, and genetic research. The physiology research focused on the physiological and biochemical metabolic pathways that plants use when exposed to drought stress. New wheat and barley genotypes having a high degree of drought tolerance are produced through breeding by making crosses from promising drought-tolerant genotypes and selecting among their progeny. Also, identifying genes contributing to drought tolerance is very important. Previous studies showed that drought tolerance is a polygenic trait and genetic constitution will help to dissect the gene network(s) controlling drought tolerance. This review explores the recent advances in these three research areas to improve drought tolerance in wheat and barley.

/pdf/drought-stress-tolerance-in-wheat-and-barley-advances-in-4mgg14wy6v.pdf

Drought Stress Tolerance in Wheat and Barley: Advances in Physiology, Breeding and Genetics Research.

Plants are often exposed to unfavorable environmental conditions, for instance abiotic stresses, which dramatically alter distribution of plant species among ecological niches and limit the yields of crop species. Among these, drought stress is one of the most impacting factors which alter seriously the plant physiology, finally leading to the decline of the crop productivity. Drought stress causes in plants a set of morpho-anatomical, physiological and biochemical changes, mainly addressed to limit the loss of water by transpiration with the attempt to increase the plant water use efficiency. The stomata closure, one of the first consistent reactions observed under drought, results in a series of consequent physiological/biochemical adjustments aimed at balancing the photosynthetic process as well as at enhancing the plant defense barriers against drought-promoted stress (e.g., stimulation of antioxidant systems, accumulation of osmolytes and stimulation of aquaporin synthesis), all representing an attempt by the plant to overcome the unfavorable period of limited water availability. In view of the severe changes in water availability imposed by climate change factors and considering the increasing human population, it is therefore of outmost importance to highlight: (i) how plants react to drought; (ii) the mechanisms of tolerance exhibited by some species/cultivars; and (iii) the techniques aimed at increasing the tolerance of crop species against limited water availability. All these aspects are necessary to respond to the continuously increasing demand for food, which unfortunately parallels the loss of arable land due to changes in rainfall dynamics and prolonged period of drought provoked by climate change factors. This review summarizes the most updated findings on the impact of drought stress on plant morphological, biochemical and physiological features and highlights plant mechanisms of tolerance which could be exploited to increase the plant capability to survive under limited water availability. In addition, possible applicative strategies to help the plant in counteracting unfavorable drought periods are also discussed.

The Impact of Drought in Plant Metabolism: How to Exploit Tolerance Mechanisms to Increase Crop Production

The quality of agricultural and horticultural products and its modulation by fertilization has increasingly received attention. However, whereas the importance of magnesium (Mg) as an essential plant nutrient is well established, the impact of Mg nutrition on quality parameters has only been rarely addressed. This review aims at evaluating the available knowledge on the influence of Mg on produce quality. A short discussion on the term quality as used in this review is followed by an overview of the various functions of Mg in plant metabolism in relation to quality aspects. Finally, the available literature on Mg-associated effects on crop quality is critically surveyed. The question whether Mg application beyond yield optimum further improves crop quality is specifically addressed. Increasing Mg supply on Mg-deficient sites tends to increase the quality of agricultural crops, particularly when the formation of quality traits is dependent on Mg-driven photosynthesis and assimilate translocation within the plant. In fruits and vegetables, ratios of Mg to other nutrients like Ca and K were shown to be a more reliable indicator of the quality response than the Mg status alone. Moreover, it is concluded that Mg doses beyond those required for maximum yield rarely induce a further improvement of produce quality.

/pdf/the-significance-of-magnesium-for-crop-quality-3e2yccfpja.pdf

The significance of magnesium for crop quality

Deoxynivalenol (DON) is a mycotoxin produced by the plant pathogenic fungi Fusarium graminearum and F. culmorum. These and other closely related fungi cause a disease known as Fusarium head blight (FHB) in small grain cereals. Other mycotoxins produced by FHB-causing fungi include nivalenol, T-2 toxin, and zearalenone. Ingestion of mycotoxin-contaminated food and feed can lead to toxicosis in humans and animals, respectively. DON is the predominant and most economically important of these mycotoxins in the majority of small grain-producing regions of the world. This review examines the factors that influence DON accumulation in small grain cereals from an agricultural perspective. The occurrence and economic importance of FHB and DON in small grain cereals, epidemiological factors and cereal production practices that favor FHB development and DON accumulation in grain under field conditions, and regulatory/advisory standards for DON in food and feed are discussed. This information can be used to develop strategies that reduce DON accumulation in grain before harvest and to mitigate the human and animal health risks associated with DON contamination of food and feed.

/pdf/factors-influencing-deoxynivalenol-accumulation-in-small-18ge07f1p6.pdf

Factors influencing deoxynivalenol accumulation in small grain cereals.

The response of drought stress on morpho-physiological and biochemical characters was assessed in black gram genotypes in a pot culture experiment. Water stress was applied at flowering stage of the crop and various morpho-physiological and biochemical characters were analyzed under control and water stress conditions. The genotypes, water levels and their interaction varied significantly for majority of the traits quantified revealing the presence of substantial genetic diversity. Based on these studies, genotypes PGRU95016, COBG05, IPU99209, IPU941 and IPU243 were identified as tolerant to drought stress conditions. Photosynthesis, stomatal conductance, transpiration rate, total chlorophyll, proline content and peroxidase activity could be useful to screen for drought tolerance in black gram.

Morpho-physiological and biochemical changes in black gram (Vigna mungo L. Hepper) genotypes under drought stress at flowering stage

Functional mechanisms of drought tolerance in maize through phenotyping and genotyping under well watered and water stressed conditions

Barley (Hordeum vulgare L.) is an important feed purpose cereal grown under diverse production conditions and harsh environments. The present investigation was carried out to study performance of advanced breeding lines and identify superior genotypes of feed barley using multienvironment trial data from All India Coordinated Wheat and Barley Improvement Programme (AICW&BIP). Ninety three experimental genotypes and five released cultivars were tested across eleven locations during four years. Grain yield and other agronomic traits were analyzed. Stability and genotype superiority for grain yield and other traits were determined using genotype and genotype × environment (GGE) biplot analysis.The result showed that environment and genotype contributed 32.9 to 67.4% and 4.7 to 20.4% of the total variation, respectively.The genotype × environment interaction contributed 27 to 44% of total variation. The experimental genotypes showed arrays of variation for grain yield in each year, with mean values ranging from 2.12 to 5.36 t/ha. Twelve experimental genotypes were identified, which were either superior or equal performance to the best check based on their high yield and stability across environments. The locations Varanasi, Kanpur,Vijapur and Durgapura discriminated the genotypes more than other sites for grain yield and agronomic traits. The findings provided valuable information on wide adaptation of feed barley genotypes, which could be useful for barley improvement programmes.

/pdf/identifying-superior-feed-barley-genotypes-using-gge-biplot-5544h0ezjh.pdf

Identifying superior feed barley genotypes using GGE biplot for diverse environments in India

Grain and malt traits important for malting quality were studied on a set of 131 genotypes including two and six row types barley of indigenous and exotic origin grown at two locations for two seasons. Observations on seven grain and seven malt traits were recorded and malting was done with Phoenix® automatic micro-malting system. The correlation studies indicated that the hot water extract (HWE) is correlated with a number of grain (hectolitre weight, plump %, thin %, protein %, TGW and hull %) and malt (friability, homogeneity, wort viscosity, filtration rate and Kolbach Index) traits either positively or negatively. The multiple regression analysis indicated that hectolitre weight, TGW, hull content and malt friability can be used to predict HWE, the ultimately important trait with malting and brewing industry, in early generations of a breeding programme or for initial screening of germplasm accessions.

/pdf/breeding-barley-for-malting-quality-improvement-in-india-4hawfw3564.pdf

Breeding Barley for Malting Quality Improvement in India

A study was conducted during 2005 to study the genetic diversity among 72 Indian barley (Hordeum vulgare L.) varieties released during last 60 years for different grain and malt quality traits. Most of these varieties were not originally bred as malt barley and there are only few varieties released as malt barley. The present study was taken up to analyze the extent of variability for malting quality in these released varieties. Observations were recorded on 7 grain and 7 malt traits. The study revealed that lot of variability exists among these varieties for individual malting quality traits. The data were subjected to clustering analysis for grouping of genotypes based on genetic diversity between groups. The hierarchical cluster analysis based on Euclidean distance and agglomerative linkage function indicated that genotypes with good malting quality were mostly grouped in cluster I and II.

B. Sarkar

Papers

Morpho-physiological and biochemical changes in black gram (Vigna mungo L. Hepper) genotypes under drought stress at flowering stage

Functional mechanisms of drought tolerance in maize through phenotyping and genotyping under well watered and water stressed conditions

Identifying superior feed barley genotypes using GGE biplot for diverse environments in India

Breeding Barley for Malting Quality Improvement in India

Diversity for malting quality in barley (Hordeum vulgare) varieties released in India