Impact of split application of nitrogen and harvesting schedule on yield and quality of sweet corn (Zea mays var. saccharata L.) under South Saurashtra condition

A field experiment was conducted during the rabi season of 2019-20 at the Instructional Farm, Department of Agronomy, College of Agriculture, Junagadh Agricultural University, Junagadh. The experimental site had clayey soil, which was slightly alkaline in reaction (pH 7.7), rich in organic carbon and medium in available nitrogen, phosphorus (P₂O₅), and potassium (K₂O). The study comprised eighteen treatment combinations arranged in a split-plot design with three replications. The main plots included two sweet corn varieties (V₁: Sugar-75 and V₂: Sweet-16) along with three nitrogen application schedules—N₁ (50% as basal + 50% at knee-height stage), N₂ (25% as basal + 50% at knee-height stage + 25% at tasseling stage) and N₃ (33.3% as basal + 33.3% at knee-height stage + 33.3% at tasseling stage). The subplots consisted of three harvesting times, viz., T₁: 20 days after silking, T₂: 30 days after silking, and T₃: 40 days after silking.

The findings revealed that the sweet corn variety Sugar-75 produced significantly higher values of green cob yield, fresh kernel yield, green fodder yield, protein yield, sugar yield, as well as nitrogen and phosphorus uptake by both dry kernel and dry fodder. Among nitrogen management practices, the schedule of 25% applied as basal, 50% at the knee-height stage, and 25% at tasseling resulted in maximum green cob yield, fresh kernel yield, fodder yield, kernel protein content, protein yield, sugar yield, kernel nitrogen content, uptake of phosphorus and potassium by dry kernel and improvement in soil nitrogen status after harvest. Harvesting at 30 days after silking significantly enhanced green cob, kernel and fodder yield, protein yield and uptake of nitrogen and phosphorus by dry kernel and fodder, along with potassium uptake by dry kernel and fodder, followed by harvesting at 40 days after silking. The highest sugar yield was observed when the crop was harvested 40 days after silking, which was statistically at par with 30 days after silking. Significant interactions between variety and harvesting time were observed for harvest index and nitrogen uptake in dry fodder. Moreover, the combined influence of variety, nitrogen split application and harvesting schedule was significant for protein yield, kernel sugar content and nutrient uptake (N and P) by dry kernel and fodder. Based on the overall results, it may be concluded that under the clayey soils of South Saurashtra, rabi sweet corn variety Sugar-75, when supplied with nitrogen in the proportion of 25% basal + 50% at knee-height + 25% at tasseling and harvested 30 days after silking, achieved superior cob, kernel, fodder and protein yields.