SREEKANTH, BBHEEMAIAH), L2019-03-162019-03-162018http://krishikosh.egranth.ac.in/handle/1/5810098724D5627The present investigation entitled “Physiological role of Silicon nutrition on yield of rice (Oryza sativa L.).” was conducted at Agricultural College Farm, Bapatla during Kharif, 2017. Eight treatments were taken, four are soil application with silixol granules and other four are foliar application with sodium silicate along with controls (no silicon and foliar application with water). Silicon was applied either through soil or foliar modes at three different stages of rice cv. BPT-5204 viz., mid-vegetative stage (20 DAT), mid-reproductive stage (55 DAT) and mid-ripening stage (85 DAT). Experiment was laid out in a Randomized Block Design with three replications. Observations on photosynthetic and biochemical parameters were recorded at 15 days after silicon application and the data on yield and yield components were recorded at harvest. From the above investigation, at all the three sampling stages silicon application either through soil or foliar forms increased the Pn, stomatal conductance, leaf area and SPAD value and decreased the transpiration rate, and this increase/decrease was more with soil application. Among the stages, except SPAD value remaining parameters were highest in mid-reproductive stage, irrespective of time and form of silicon application. Soil application with silixol granules at three different stages increased the reducing, non-reducing, total sugar and silicon contents of rice leaf and culm. Foliar application with 1 % sodium silicate increased the parameters like starch content, protein content and starch phosphorylase activity of rice leaf and culm. The increasing effect of biochemical parameters of leaf and culm were low in vegetative stage and reached to maximum at reproductive stage and then decreased at ripening stage, irrespective of time and form of silicon application. Grain constituents like reducing, non-reducing, total sugar and silicon contents were increased with soil application of silicon. But foliar application of silicon, increased the grain parameters like starch content, protein content and starch phosphorylase activity and this increasing effect was more prominent during reproductive stage of silicon application than vegetative and ripening stages, either through soil or foliar modes. Yield and yield attributing characters like number of spikelets per panicle, filled spikelet percentage, test weight, harvest index, grain yield per panicle and grain yield ha-1 were increased by soil application of silicon, while panicle length, spikelet length, number of primary and secondary branches of panicle were increased by foliar application of silicon and this increase was more at mid reproductive stage than other stages, irrespective of form of silicon nutrition. The computations of correlation among the parameters revealed that there was a strong relation between leaf, culm and grain silicon contents and their photosynthetic, biochemical and yield attributes of rice and this was more prominent during reproductive stage of crop than at vegetative and ripening stages of Si application.en-USnullThesis