Krishnendu Chattopadhyay

Stability analysis of backcross population for salinity tolerance at reproductive stage in rice

Significant yield reduction was recorded at flowering stage in rice varieties under salinity stress. But due to high genotype x environment interaction (GEI) the adaptability of the salt tolerant elite lines is generally poor. The identified source of tolerance, AC41585, was used in developing a backcross population. One hundred eighty BC3F4 lines were evaluated under stress (EC 8dSm−1) and non-stress conditions in net-house during the years 2012 and 2013. Under salinity stress plant yield was observed to be associated positively with the number of panicles/plant, panicle length, harvest index and negatively with the percentage of spikelet sterility and degeneration. Genotypes such as, L-41, L-45, L-112, L-171, L-192 with low IPCA and higher mean were identified with general adaptability through AMMI analysis. In addition, ‘which-won-where’ pattern of GGE Biplot detected L-192 and L-41 as highest performing genotypes in saline and non-saline environments, respectively. Both the analyses identified stable introgression line L-171 with high yield stability index having phenotypic similarity with recurrent parent, IR 64. The elite lines selected through the present study could be used in rice breeding and also to investigate the molecular basis of salt tolerance at reproductive stage.

Comparison of Nutritional and Physicochemical Quality of Rice Under Organic and Standard Production Systems

Growing interest in sustainable agriculture has prompted this study aiming to evaluate nutritional content of rice grain produced from an organic production system. Here, we grew nine quality rice cultivars under organic methods in the wet and dry seasons, and the nutritional values, grain quality, and physiological parameters were compared with respective cultivars grown under the standard cultivation method (SCM). Obtained results revealed that the yield and plant height were lower, but tillering capacity was higher, in the organic field compared with the standard one. The organic crop showed significantly lower contents of protein and phytate compared with reference values under the SCM. Antioxidative capacity and its responsible phytochemicals such as phenolics, flavonoids, and γ-oryzanol were also significantly higher under organic cultivation than under the SCM. Among physicochemical characteristics, apparent amylose content, gel consistency, and area and perimeter of grain were also higher in the o...

Ionic Basis of Salt Tolerance in Plants: Nutrient Homeostasis and Oxidative Stress Tolerance

Salinity, recognized as a major threat in agriculture, causes 4.0–6.3% yield loss annually across the world. The problem is aggravated due to increasing irrigation with suboptimal quality of irrigation water and more salinization of coastal area due to the rise in sea level because of climate change. In saline soil, excessive concentrations of Na+ and Cl− impair absorption of other beneficial ions such as K+ and Ca2+ that in turn inhibit plant growth and productivity. Maintenance of cellular K+ level and K+/Na+ ratio is still considered the most important factor for salt tolerance. Under high-Na+ environment, excess Na+ competes with K+ thereby hindering its uptake. Tolerant plants by employing a number of strategies restrict Na+ movement to young meristematic tissues and allow greater movement and/or tissue retention of K+ to physiologically more active tissues. Under salt stress different K+- and Na+-specific transporters, viz. SOS, NHX, and HKT family transporters (regulate cellular Na+ movement) and HAK, AKT, KT, and KUP (regulate K+ movement), either by upregulation or downregulation, control the cellular ion homeostasis and salt tolerance in plants. SOS1, a plasma membrane-bound Na+/H+ antiporter, mostly active in root tissue, removes the excess salt from the plant body by pumping them back to the rhizosphere in an energy-dependent process. Tonoplast-bound vacuolar Na+/H+ antiporters (NHX family transporters) play crucial role in Na+ compartmentalization inside the vacuole in mature cell in both root and leaf tissues. Storing excess salts in vacuole imparts tolerance in multifaceted manner, viz. imparting tissue and osmo-tolerance. Biosynthesis of organic osmolytes, a more energy-expensive process, is sometimes substituted by the accumulation of excess Na+ in non-active tissues under salt stress. Improved Ca2+ status inside the plant tissue is another important factor associated with salt tolerance and acts as a key signalling molecule to initiate Na+ exclusion. Several QTLs and miRNAs were reported to impart salt tolerance in several crops. Managing salinity beyond crop improvement strategies was also deliberated, e.g. lowering salt effect through K+ supplementation and phytohormones, etc. In this compilation, emphasis has been given on how nutrient/ionic imbalance causes deleterious effects on plants under saline conditions and what are the possible adaptive strategies plants employ to maintain the ionic homeostasis in saline environment.