Vol. 16 No. 3
Effect of varying fertility levels on physiological aspects of rice cultivars in the North Western Himalayas
Author(s): N. KUMAR, B. S. MANKOTIA, S. MANUJA, B. PAREEK, P. KUMAR, R. SHARMA AND I. S. MANDIAN
Abstract: A field experiment was conducted during kharif 2018 at Rice and Wheat Research Centre (RWRC), Malan to study the physiological response of different rice cultivars to varying fertility levels in mid-hills of Himachal Pradesh. The experiment consisted of 5 main-plot treatments comprising varying fertility levels {50% recommended dose of fertilizer (RDF), 100% RDF (90:40:40 kg N:P:K ha-1), 150% RDF, 50% RDF + Azolla and 100% RDF + Azolla} and 4 cultivars as sub-plot treatments {Vivekdhan 65, HPR 2143, HPR 2720 (red rice) and AZ 6508 (hybrid)}. The soil of the experimental site was silty clay loam in texture, acidic in reaction, medium in available nitrogen, phosphorus, and potassium. The increase in fertility level and Azolla application increased the dry matter accumulation and leaf area index of rice. The increasing trend in crop growth rate (CGR) during the active tillering and flowering stage was observed while the leaf area ratio reduced from 60 to 90 days after transplanting (DAT). Contrary to these the relative growth rate (RGR) and net assimilation rate (NAR) remained almost equal during both the time intervals between 30 and 60 days and 60 and 90 days after transplanting though it varied with varying fertility levels as well as between different cultivars. Additional azolla application at both the fertilizer doses of 50 and 100 % RDF showed a significant increase in CGR from 30 to 60 DAT as compared to the when it was not applied, the increase being 2.70 and 2.13 g m-2 day-1 with the azolla application at 50 % and 100 % RDF, respectively. Further CGR recorded between 30 and 60 DAT with the application of azolla with 50 % RDF was statistically similar to the application of 100 % RDF alone, indicating a saving of 50 % RDF with the azolla application. Also the CGR recorded between 30 and 60 DAT with the application of 150 % RDF was also similar to the application of 100 % RDF along with azolla application. Similarly RGR increased with increasing fertilizer application as well as with azolla application at 30 to 60 and 60 to 90 DAT. LAR decreased during the flowering stage due to more contribution of flag leaf in net assimilation. Among the cultivars tested ‘Vivekdhan 65’ and ‘AZ 6508’ showed higher values of CGR as well as RGR, particularly between 60 to 90 DAT while ‘AZ 6508’ had significantly higher LAR. Initially, azolla applied to the crop was not much effective but during the later stages, its contribution increased the growth rate. These findings suggest that growth indices could be enhanced by applying higher doses of fertilizesr but the application of azolla can result in the saving of fertilizers.
Download Full Article: Click Here