Response of upland rice(Oryza sativa L.) to NK ratios and S under partial shade

Abstract

A field experiment was conducted at the Instructional Farm of the College of Agriculture, Vellayani during the first crop season of 2004 to study the response of upland rice to NK ratios and S nutrition under partial shade of coconut garden. The treatments included six levels of N and K in 2 : 1 and 2 : 1.5 ratio (T1 – 80 kg N : 40 kg K2O, T2 – 80 kg N : 60 kg K2O,T3 – 100 kg N : 50 kg K2O, T4 – 100 kg N : 75 kg K2O, T5 – 120 kg N : 60 kg K2O, T6 – 120 kg N : 90 kg K2O) and two levels of sulphur (S0 – 0 kg ha-1, S1 – 15 kg ha-1). Farmyard manure @ 5 t ha-1, P @ 30 kg P2O ha-1 were applied uniformly to all the treatments. Experiment was laid out in 6 x 2 randomized block design with three replications. Results of the experiment revealed that NK ratio and S application had significant influence on most of the yield attributing characters and yield of upland rice. Fertilizing the crop with 100 kg N ha-1, 50 kg K2O ha-1 and 15 kg S along with 30 kg P2O5 was found to significantly influence the growth characters, yield attributes and yield of rice. The physiological characters like chlorophyll content and relative leaf water contents were significantly influenced by NK ratio of (100 kg N : 50 kg K2O). Application of S significantly increased the physiological parameters. Application of 15 kg S in combination with 100 kg N and 50 kg K2O ha-1 significantly influenced the physiological parameters over control. Quality attributes like protein content of grain was significantly influenced by the application of 100 kg N and 50 kg K2O in combination with 15 kg S ha-1. The uptake of nutrients was profoundly influenced by the treatments and their interactions. Increased uptake of nutrients was recorded at an NK ratio of 100 kg N : 50 kg K2O. Application of S @ 15 kg ha-1 in combination with 100 kg N and 50 kg K2O ha-1 had a significant influence on uptake of nutrients. Increasing the levels of nitrogen, potassium and sulphur increased the soil available nutrients. Application of N at 120 kg, K at 90 kg K2O ha-1 and S at 15 kg ha-1 significantly improved the available nutrient status of soil. The results of the economic analysis revealed that benefit cost ratio was maximum in plots supplied with 100 kg N, 50 kg K2O and 15 kg S ha-1. Based on this investigation, it can be concluded that application of 100 kg N, 50 kg K2O and 15 kg S ha-1 along with 30 kg P2O5 ha-1 is necessary for obtaining economic yield of upland rice variety Harsha under partial shade.