On-farm Evaluation of Leaf Colour Chart and Chlorophyll Meter for Need-based Nitrogen Management in Kharif Maize (Zea mays L.)

Background: Soil is important medium of all living beings. Due to the high doses of fertilizers application soil heath is getting deteriorated. Soil fertility variation restricts efficient fertilizer N management when broad based blanket recommendations are used in maize (Zea mays L.). Site-specific fertilizer nitrogen management (SSNM) could be the best management option to avoid excessive and untimely nitrogen (N) applications in maize. Methods: A field experiment was conducted at Agronomy Farm, Lovely Professional University, Phagwara during kharif season of 2020 and 2021 to study the nitrogen management using leaf colour chart (LCC) and chlorophyll meter in maize (Zea mays L.). Colour (of the first top maize leaf with fully exposed collar) as measured by comparison with different shades of green colour on a leaf colour chart (LCC) and also by SPAD meter. Need based fertilizer application at LCC5 and SPAD 50 significantly improved growth and yield attributes viz., plant height, dry matter accumulation plant-1, number of leaves plant-1, stem diameter, number of internodes plant-1, leaf area index, cob length, cob girth, number of cobs plant-1, number of grains cob-1, grain weight plant-1 and 1000-grain weight along with higher grain and stover yields, grain protein content over fixed time application of 1200 kg N ha-1. Result: Evaluation of the established threshold leaf greenness revealed that fertilizer N management using LCC 5 and SPAD 50 starting from six-leaf stage to before silking stage resulted in improved agronomic efficiency in maize. There was no response to fertilizer N application at silking stage. The study concluded that in maize, fertilizer N can be more efficiently managed by applying fertilizer N dose based on leaf colour as measured by LCC than blanket recommendation.