Phenology, growth and productivity of rice (Oryza sativa l.) under reduced sunlight intensity and foliar nitrogen application

Abstract

The field experiments related to the study were conducted at Punjab Agricultural University, Ludhiana and Krishi Vigyan Kendra, Bahowal. There were 20 treatment combinations comprising of four levels of sunlight intensity [control (full sunlight), 50% reduction in sunlight light intensity during 15-45(R15-45), 46-75(R46-75) and 76-105(R76-105) DAT] and five levels of foliar nitrogen application [control (only recommended nitrogen, no foliar spray), spray of 3% urea before (NB), midway(NM), afterwards(NA) and midway-afterwards(NMA) the reduction in sunlight intensity in addition to the recommended nitrogen application]. Radiation level of R15-45 significantly preponed (2-5 days) the occurrence of phenological stages from maximum tillering to physiological maturity. Similarly, R46-75 significantly preponed (3-9 days) the occurrences of flag leaf initiation to physiological maturity. The nitrogen level of NB, significantly delayed the occurrence of flag leaf initiation to physiological maturity stages (2-5 days), NM delayed flag leaf initiation to physiological maturity (2-4 days), NA delayed anthesis to physiological maturity (1-4 days) and NMA delayed panicle emergence to physiological maturity (2-5 days). Plant height of rice was significantly increased due to R15-45 (5.21-5.26%) and R46-75 (6.95-7.61%) and also with foliar nitrogen application levels of NB, NM, NA and NMA by 9.95-9.89, 9.65-10.06, 8.06-7.57 and 9.65-9.29 per cent, respectively. Number of tillers m-2 was significantly reduced (4.71-15.99%) under low light conditions and was increased (5.59-23.34%) with foliar nitrogen application. Yield attributes were affected by the reduced sunlight intensity and foliar nitrogen application. Grain yield was significantly reduced as a result of R15-45 (9.19-11.41%), R46-75 (14.29-16.35%) and R76-105 (8.15-10.67%) and foliar nitrogen application levels of NB, NM and NMA resulted in significant increase the grain yield by 9.32-10.19, 5.74-6.38 and 4.59-5.74 per cent respectively, as compared to control.