Salinity induced variability in morpho-physiological traits and their relationship with grain yield in rice ( Oryza sativa L.)

摘要

Salinity is one of the most important abiotic constraint causes significant yield losses in rice crop specially when occur at flowering stage. The losses are mainly due to excessive accumulation of toxic ions mainly sodium in shoot affecting physiological processes osmotically and ionically. Twelve rice genotypes were studied under hydroponically controlled saline conditions (50 mM NaCl) along with non-saline control. Variability of sodium in shoot was assessed at vegetative, flowering and maturity stages and the impact of sodium accumulation on physiological traits of chlorophyll, proline, potassium sodium ratios and total soluble sugars were explored at flowering stage. Furthermore, significance of physiological traits in relation to adaptation of growth and yield under salt stress were also investigated. These studies revealed differential behavior of genotypes in their sodium uptake. Significant gradual increase in shoot sodium concentrations was observed under salinity at each stage of growth. Genotypic comparisons have shown that genotypes RST-177, RST -179, Shua-92-155/E, FL- 478, Kharaganja and IR-9 exhibited significantly low sodium concentrations and high potassium and sodium ratios. Highest sodium concentrations were observed in GML-528, GML-529 followed by GML-538. Results have also revealed variable increase in their total soluble sugars and proline concentrations. Highest concentrations of proline and total soluble sugars were found in GML-529, GML-538 and GML-528.Whereas, the lowest proline concentrations were observed in FL-478 followed by IR-9 and RST-177. Correlation studies among physiological traits revealed that the trait of sodium was significantly positively correlated at p 0.01with proline (r =0.7521) and sugars (r =0.8319) and negatively correlated with grain weight (-0.6923). The grain weight was negatively correlated with proline and total soluble sugars. Significant positive correlation of grain weight was observed only with K: Na ratio (r = 0.5355). On the basis of these studies it may be concluded that chlorophyll pigments, low sodium concentrations more specifically high potassium sodium ratios were observed as adaptive traits.