Salinity is one of the major factors reducing plant growth and productivity worldwide and affects about 7% of world's total land area. In India about 6.73 million hectare of land area is salt affected. Wheat is the second most important crop after rice in India and occupies approximately 28.5 million hectare area. Several tolerance indices comprising of mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), stress stability index (SSI), tolerance index (TOL), yield index (YI) and yield stability index (YSI) were calculated in this investigation for salinity and its ability to understand which one or more predictor among studied indices based on correlation, principal component analysis and cluster analysis. Ten wheat genotypes were evaluated in two successive growing seasons (2012)(2013)(2014), with complete randomized design with three replications under both salinity stress and non-salinity to identify salt tolerant genotypes to the target environment. Multiple indices for salt tolerance were calculated based on the potential yield (Yp) under non-stress and yield (Ys) under stress conditions. The Ys and Yp showed highest significant and positive correlations with GMP, MP and STI among indices studied. Therefore, these indices were considered as a better predictor of Ys and Yp than TOL, SSI and YSI. Principal component analysis classified the genotypes into two groups. The first two PCs with eigen values >1 contributed 99.74% of the variability amongst genotypes. PC1 accounted for about 5.24% of the variation in salt tolerance indices and PC2 for 3.74%. The first PC was related to Ys, Yp, MP, GMP, STI and YI whereas the second PC related to Yp, TOL and SSI. The cluster analysis sequestrated ten genotypes into two clusters based on Ward's method. According to results, salinity significantly reduced the yield of some genotypes while some were found tolerant to stress indicating sufficient genetic variability for salinity tolerance among the studied genotypes. It could be implicated in selection of salinity tolerant wheat genotypes for the development of bread wheat varieties.
For sustainable production of sugarcane, healthy and more acclimatized plants should be developed that can easily cope up all the environmental barriers of biotic and abiotic stress. Soil salinization is one of these kinds of stress that limits the productivity of crops worldwide. We have investigated the proline content of plant under normal and two different levels of salt irrigation water (ECiw10dSm -1 and ECiw 20 dSm -1 ) consecutively for two years of crop production in 2015-16 and 2016-17. Ten sugarcane varieties (Co 0118, Co 0238, Co 5011, CoLk 99270, CoS 8279, CoSe 8457, Co 5009, CoS 7250, CoPant 97222, Co 98014) were planted in the replicate of three under complete randomized design. Salt treatments were given at formative stage and the tests were performed at grand growth stage of plant life cycle. Effect of salinity can be seen on other phenotypic factors of plant also in correlation with proline. On exposure to salt stress, tolerant varieties CoPant 97222, CoS 7250, Co 98014 were found to accumulate more proline than to varieties Co 0238, CoSe 8457 and Co 0118, while CoS 8279, Co 5011 and Co 5009 show moderate behavior.
Water stress is one of the foremost categories of stress damaging plants’ overall growth and development. The aim of the present study was to explore and demonstrate stress-induced drought to calibrate changes in stress parameters of two banana plant varieties viz. Grand naine (G9) and Nalla bontha were cultured in Murashige and Skoog medium (MS) media supplemented with stress inducers -Poly ethylene glycol (PEG) and sorbitol. The different concentrations of inducers were used to induce drought stress in two varieties of banana with contrasting characters for drought condition. The study indicated that PEG contrived mild to moderate osmotic stress and so does the alditol i.e. sorbitol on in vitro banana plants. The different concentrations of PEG and sorbitol produced significant effects on various parameters. The maximum decrease in shoot length was prominent in G9(52%) as compared to Nalla bontha (11%). When treated with 3% w/v sorbitol, even average root length showed the same level of damage with G9(59%) while in case of Nalla bontha there was a 17% decrease. The banana plantlet produced in vitro was estimated at one and two weeks after inoculation, respectively. Proline content tended to increase as the concentration of osmotic inducers increased (-44 % in G9 at 3% w/v sorbitol), whereas RWC (8.9% in G9 at 3% w/v Peg) showed an opposite effect. It was concluded that quantitative and qualitative changes in physiological (shoot and root length) and biochemical (Proline and relative water content, RWC) parameters played an important role in plants under drought stress conditions. This pattern varied from species to species. This work has been attempted for the first time in banana, especially Grand naine varieties with contrasting characters under induced drought stress.
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