Calibrating leaf colour chart for nitrogen management in Rabi maize (Zea mays L.) under varied plant density

Abstract

Many farmers are applying nitrogen fertilizer to maize in large quantities than crop requirement to obtain maximum possible yield in maize. A field experiment was conducted at the Wet land farm of Sri Venkateswara Agricultural College, Tirupati during Rabi season of 2017-18 to calibrate Leaf colour chart for nitrogen management under varied plant density and to establish threshold leaf colour greenness to guide in-season right quantity fertilizer N for top dressing in maize. The experiment consisted of twenty seven treatment combinations comprising of three planting densities (66,666, 83,333 and 1,11,111 plants ha-1), three nitrogen levels (30, 35 and 40 kg N ha-1) and three LCC threshold values (LCC 4, 4.5 and 5). Yield attributes like number of cobs plant-1, cob length, cob girth, number of kernel rows cob-1 and number of kernels row-1 were significantly higher at lower planting density but, kernel yield (6004 kg ha-1) was significantly maximum at higher stand density (1,11,111 plants ha-1). Pertaining to nitrogen application based on leaf colour chart (LCC), maximum yield was registered at higher rate of nitrogen 40 kg N ha-1 by using higher LCC threshold value (LCC-5). Experimental results disclosed that, in maize N fertilizers can be managed more efficiently by supplying fertilizer nitrogen levels based on leaf colour as measured by LCC than blanket recommendation.