Zero tillage and nitrogen supplementation using chlorophyll meter in irrigated wheat

Experiment was carried out using chlorophyll meter in order to adequate use of nitrogen in wheat crop on alluvial soil of eastern India. The experiment was laid out in split plot design with fourteen treatment combinations of two SPAD levels (42 and 44) as main plot and seven wheat cultivars as sub plot during the dry season of 2015–16 in Sabour, Bhagalpur. Herein the study, growth attributes in SPAD 42 were found comparable with SPAD 44 in most of the cases, using considerably less amount of N (19%) than SPAD 44. The highest grain yield (5172 kg ha⁻¹) was recorded in cultivar HD 2967 followed by Sabour Samriddhi (4817 kg ha⁻¹) and both these cultivars were significantly superior over the cultivar PBW 343 which had scored the lowest productivity among the sub plot treatments. Similar trend was noticed in case of straw yield, where SPAD 42 and 44 were comparable likewise in grain yield. Study confirmed that chlorophyll meter based N management, especially maintenance of SPAD threshold value of 42 with N application of 20 kg ha⁻¹ in each top dressing could save substantial amount of N along with the positive impact on grain yield.