Growth and productivity of wheat (Triticum aestivum) as influenced by potassium application

Abstract

A field experiment was conducted during winter (rabi) seasons of 201516 and 201617 at New Delhi to as- sess the effects of rate, methods, time and sources of potassium (K) fertilization on wheat (Triticum aestivum L.) growth, growth indices, yield and returns from investment on K. Application of 60 kg K O/ha in 2 splits, half basal 2 and remaining half at spike initiation stage or 75% basal and remaining 25% at spike initiation stage increased the grain yield (5.5 t/ha) by 8.8% over applying entire dose as basal. The split application of recommended dose of K (RDK) also increased the growth parameters (plant height, dry-matter, leaf area index) and growth indices [crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR)] significantly over control. All the growth parameters and growth indices were recorded the highest with 75% RDK as basal + 25% at spike initiation + 2 foliar spray of 2.5% KNO (68.8 kg K O/ha), whereas control recorded the lowest. A strong positive and signifi- 3 2 cant correlation was observed between dry matter production and grain yield during 90 days after sowing (DAS) (R2=0.76) and 120 DAS (R2=0.74). Similarly, positive and significant correlation was also observed between LAI and grain yield during 90 DAS (R2=0.72) and 120 DAS (R2=0.71). The highest returns from investment on K fertil- izer was obtained with 2 foliar spray of 2.5% KNO , whereas 150% RDK as basal gave the lowest returns. Applica- 3 tion of 60 kg K O/ha in 2 splits (50:50 or 75:25 ratio) increased returns from investment on K 4 by over applica- 2 tion of entire dose as basal. Thus, for wheat, application of 60 kg K O/ha in 2 equal splits (50% as basal + 50% at 2 spike initiation) is recommended to realize maximum benefit from K fertilization.