Effect of Scheduling Irrigation at Different Phenophases of Sweet Corn (Zea mays saccharata) and Delineation of Critical Stages Based on Stress Day Index

Abstract

A field experiment was conducted during the summer of 1996 at the Main Research Station, University of Agricultural Sciences, Hebbal, Bangalore to study the effect of phenophased irrigation schedules on green cob and fodder yield and to delineate critical stages based on Stress Day Index. There were seven irrigation schedules consisting of a combination of two IW/CPE ratios (irrigation water/cumulative pan evaporation), viz. 0.6 and 0.8 shuffled at three growth stages: 10–35 DAS (days after sowing), 36–65 DAS and 66 days to harvest in RCBD (randomized complete block design) with four replications. The investigations revealed that all yield attributing characters such as cobs per plant, cob weight, green cob and fodder yields were significantly higher under the irrigation schedule of 0.8 IW/CPE ratio throughout the crop growth. The reduction in green cob and fodder yields were 39 and 25 % respectively, when irrigations were scheduled at 0.6 IW/CPE ratio throughout as compared to 0.8 IW/CPE. Also, frequent irrigation at 0.8 IW/CPE ratio throughout maintained higher plant relative water content (86.90 %) and higher available soil moisture (59.95–81.51 %) before irrigation as compared to delayed irrigations at 0.6 IW/CPE ratio. The quality parameter viz. sucrose content (2900 μg g−1) in developed seeds was also higher under frequently irrigated treatment. The stress day index indicated that vegetative followed by silking and tasseling were the critical stages for moisture stress.