Real-Time Nitrogen Application of Rice Varieties Based on Leaf Colour Chart under System of Rice Intensification in Temperate Climate

Abstract

Increasing nitrogen use efficiency in rice intensification (SRI) is pivotal to achieving high crop yield and reducing nitrogen losses. To find the critical value of the leaf color chart (LCC) for real-time nitrogen (N) application in rice varieties under SRI, a field experiment was laid at the Research Farm, Faculty of Agriculture, Wadura, SKAUST-Kashmir in Kharif between 2019 and 2020. The experiment comprised two cultivars (SR-3 and SR-4) and eight LCC-based nitrogen managements (control, recommended dose of nitrogen (RDF), and three LCC scores (≤3, ≤4, ≤5 each with 20 and 30 kg N ha−1). SR-4 produced significantly higher values for growth and yield parameters, producing higher grain yield (7.02 and 6.86 t ha−1) compared to SR-3 (6.49 and 6.36 t ha−1) between 2019 and 2020, respectively. An LCC value of 5 with 30 kg N ha−1 produced maximum grain yield (7.84 and 7.70 t ha−1) in 2019 and 2020, respectively, which were statistically at par with the LCC value of 5 with 20 kg Nha−1. Pooled data revealed that the highest B: C ratio of 1.55 was recorded in cultivar SR-4 with an LCC value of 5 with 30 kg N ha−1. Furthermore, agronomic and recovery efficiency of nitrogen remained maximum in LCC 5 with 20 kg N ha−1 for both years. Grain yield recorded in LCC 3 20 kg N ha−1 was similar to recommended nitrogen. The present study highlighted the need-based N application through LCC and proved effective in increasing the N-use efficiency and yield in rice.