Crops weather relationship in rice

Abstract

An experiment was conducted in the Agricultural research Station, Mannuthy during first, second and third crop seasons of 1998-99 to study the crop weather relationship in rice variety 'Kanchana'. The experiment was laid out in randomised block design with three replications. The treatment consisted of three dates of planting in each season i.e., 1 s\ i s" and 30th of June, 1 st 15th and 30th of October and 1 st, 15th and 30th of January. Observations on morphological and yield attributes were recorded during the course of investigation. The daily values of weather elements viz., maximum and minimum surface air temperature, bright sunshine, morning and afternoon relative humidity and wind speed were collected from the Principle Agro Meteorological Station, College of Horticulture, Vellanikkara, to work out the crop weather relationships in rice. . Crops transplanted on 1 st is" and 30tl) of October and 1 st 15th of June were significantly superior in terms of grain yield, panicle number, number of filled grains/panicle, number of leaves, plant biomass, number of tillers and leaf area index. The crop weather relationship studies showed that the wind speed, minimum temperature and mean temperature during flowering to maturity had a significant negative correlation with grain yield. But morning relative humidity and mean relative humidity during transplanting to panicle initiation stage had a significant positive influence on ultimate grain yield. The wind speed, mean temperature, temperature range, RH1-RH2 and solar radiation during vegetative stage were negatively correlated with the straw yield. Maximum temperature during beginning of grain filling to maturity stage also

had a negative correlation. But increase in mimmum temperature, mean relative humidity, morning and afternoon relative humidities during transplanting to flowering stage was significantly increase the straw yield as there was a positive correlation. The regression equations developed in the study predicted the grain yield, straw yield, duration of vegetative phase and maximum leaf area index well and a close relation existed between observed and estimated yield. Based on the experimental data, minimum data set for the validation of rice model of the IBSNAT has been generated.