Influence of seedling age on growth, productivity and heat use efficiency of rice genotypes in North West India

An experiment was conducted at Punjab Agricultural University, Ludhiana, India during kharif 2017 and 2018 to determine the effect of seedling age on growth, phenology thermal energy utilization by different rice genotypes. The field laid–out in factorial RCBD design keeping three (25, 35, 45 days) four genotypes (PR 121, PR 122,PR 124, 126) with replicates. prevalence dry weather conditions especially September month 2017, which coincides graingrowth phase congenial for crop reflected yield attributes. There consistent decline grain straw increase due reduced leaf area index (LAI), matter partitioning grain/culm SPAD value. This may be higher range minimum temperature resulting into more respiratory losses thereby leading lower heat use efficiency. Among genotypes, 126 found most efficient owing its shorter duration (93.9 days), where as 121 122 recorded highest accumulation growing degree number panicles m-2 along bold grains. It also observed that increasing beyond 25 days caused sharp 124 through m-2,SPAD value AGDD; while gave similar when transplanted using older seedlings. Harvest did not differ various treatments.