查看文章

Manganese (Mn), one of the most important micronutrient, is a key regulator of photosynthesis that is the major determinant of growth and yield in plants. A rapid increase in Mn deficiency in Punjab soils has imposed a need to grow Mn-efficient rice genotypes exhibiting yield at low inputs that can sustain crop production. The present investigation was conducted to characterize the morphophysiological traits for Mn efficiency in 12 genotypes of rice categorized as Mn-efficient (PR116, PAU201, PR115 and PR120) moderately Mn-efficient (3108, PUSA44, 3139 and 3141) and Mn-inefficient (3133, 3142, 3056 and 3124). Rice genotypes were grown in Mn-deficit soil (2.2 ppm available Mn) at two Mn levels (0 & 50 ppm). Per cent decline in grain yield, grain weight/panicle, grain size and grain number/panicle under Mn deficiency was less in Mn-efficient genotypes indicating that these genotypes retain high yielding attributes under Mn deficit-conditions. Higher leaf area of Mn-efficient genotypes resulted in higher accumulation of dry matter in different plant parts at both Mn levels. The root length explained 94% variation in dry matter yield at flowering and 63% at tillering indicating that root length is one of the most important parameter contributing to yield. Mn-efficient genotypes maintained higher nitrate reductase activity (NRA) than inefficient genotypes under Mn deficiency. Grain yield was strongly related to grain weight/panicle (r= 0.951) and number of grains/panicle (r= 0.932) under Mn deficiency. Thus root length, dry weight and yield contributing parameters can be used as an index of Mn efficiency.