Contribution of growth and physiological characteristics in yield of field grown rice varieties in low country dry zone

Abstract

A field experiment was conducted during the season of Maha 2017 at the AgroTech Park, South Eastern University of Sri Lanka which is located in Malwatha, Ampara district of Sri Lanka to evaluate the leaf stomatal characteristics and its influence on above ground biomass and grain yield of new improved rice cultivars namely AT 362 and BG 94-1. The experiment was laid out in a Randomized Complete Block Design (RCBD) with four replicates. Parameters on stomatal conductance, growth characters namely plant height, number of productive tillers, unproductive tillers and yield contributing characters such as panicle length, panicle weight and straw weight were recorded. The data obtained were analyzed with paired t-test using STATA software and further correlation and regression were tested using SPSS. It has been found that stomatal conductance, plant height and panicle weight were varied significantly (P<0.05) among the tested varieties. However, productive tillers, unproductive tillers, straw weight and panicle length were not significantly different (P>0.05) among treatments. At harvesting, the maximum plant height (64.25 cm) was notified in AT 362 and the lowest (56.58 cm) was found in BG 94-1. During reproductive stages, panicle weight was strongly and positively correlated (r = 0.999) with parameters of stomatal conductance, plant height, productive tillers, panicle length and above ground dry matter (AGDM). It indicates that about 99.8% variation in panicle weight could be explained by the variation in evaluated characteristics. Further, linear regression for above ground dry matter and stomatal conductance showed a non-significant (p>0.05) positive correlation (r = 0.687). The value of R2 (0.473) indicates that about 47.3% variation in stomatal conductance could be explained by the variation in AGDM. Meanwhile, AT 362 significantly performed better than the variety BG 94-1 for growth and yield characters namely panicle length (19 cm), panicle weight (291.5 gm-2) and straw weight (251.3 gm-2). Thus, the results of various characters studied in the experiment depict that crop yield would be improved further by altering stomatal properties and ultimately impact the photosynthetic capacity.