Response of lowland rice cultivars to nitrogen application-A modelling approach
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Date
2017-08
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College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University , Imphal
Abstract
A field experiment was conducted the Research Farm of College of Post-Graduate Studies, Umiam, Meghalaya during kharif season of 2016 following Factorial Randomised Block Design with three replications. The soil of the experimental site was sandy clay loam soil in texture having pH 4.82 and organic carbon 3.28%. The available N, P and K was 359.9, 17.6 and 196.4 kg ha-1, respectively. Three rice cultivars (CAU-R1, Shahsarang1 and Lumpnah1) were grown with four nitrogen levels (60, 80, 100 and 120 kgN ha-1) for the study. Data generated in the study were used for calculation of genetic coefficients and calibration of DSSAT CERES-Rice model.
Shahsarang1 recorded significantly higher plant height over the CAU-R1and at par with Lumpnah1. A significant difference was observed in tillers per hill at 60, 90DAT and at harvest. Shahsarang1 was significantly superior over Lumpnah1 and at par with CAU-R1 at 90 DAT and at harvest. The dry weight of biomass in Shahsarang1 showed significant superiority at 90 DAT and at harvest over other two varieties. At 30 DAT Shahsarang1 showed significant difference between CAU-R1 and at par with Lumpnah1.Leaf area and leaf area index showed significant superiority of Shahsarang1 over CAU-R1at all the stages of observation and at par with Lumpnah1 at 90 DAT. Shahsarang1recorded highest panicle length over Lumpnah1 and at par with CAU-R1. Test weight was maximum in CAU-R1 which was significantly higher over Shahsarang1 and at par withLumpnah1. Highest grain yield and above-ground-biomass yield were obtained from Shahsarang1 which was significantly superior over Lumpnah1 and CAU-R1, Grain yield of CAU-R1 was at par with Shahsarang1. Total N and K uptake in grain, straw were maximumin Shahsarang1 following by CAU-R1 and Lumpnah1.
Production of tillers per hill varied significantly due to nitrogen levels at 60 DAT and at harvest. Successive increase in nitrogen level produced significantly more number of tillers and leaf area. At 30 DAT and 60 DAT, 120 kg N ha-1 showed significantlyhigher leaf area over the 60 and 80 kg N ha-1 and at par with 100 kg N ha-1. However, most of the growth parameters had not shown statistically significant difference but increased with each level of nitrogen resulting increase in plant height, tillers hill-1, leaf area, leaf area index and dry matter production, CGR, RGR and higher values were recorded at 120 kg N ha-1 compared to 60 kg N ha-1. Number of filled grain panicle-1 was highest at 120 kg N ha-1which was significantly superior over 60 kg N ha-1. However, Nitrogen level 120 kg ha-1 at par with 100 and 80 kg N ha-1. Nitrogen levels significantly affected the potassium uptake by grain and total potassium uptake. Nitrogen levels of 120 kg ha-1 recorded significantly more potassium uptake in grain which was at par with 100 kg N ha-1 but significantly superior over 80 kg ha-1 and 60 N kg ha-1. Due to nitrogen levels soil organic carbon showed the significant difference. Highest soil organic carbon was obtained from the nitrogen level at 80 kg ha-1 which was superior over the N level of 120 kg ha-1 and at par with 100 and 60 kg N ha-1.
Genetic coefficients were calculated from the field experiment data and used for the calibration of the CERES-Rice model. Predicted grain yield and above ground biomass yield was well agreed with observed yield, but anthesis day and maturity day were underestimated by the model for CAU-R1 and Lumpnah1. For Shahsarang1, all the parameters, viz. predicted anthesis day, maturity day, grain yield and above ground biomass yield were much close to the observed yield.