Irrigation Water Use Efficiency and Water Productivity of Commercial Sugarcane Hybrids under Water-Limited Conditions

摘要

The escalating deficit rainfall scenario in India indicates that drought is a recurrent phenomenon associated with tropical sugarcane farming, and the availability of irrigation water for sugarcane cultivation will be much less in coming years. To meet the challenge of limited and costly water supply, tropical sugarcane growers mil have to find ways of increasing the efficiency of irrigation to maintain high cane yields. More efficient irrigation systems，accurate irrigation scheduling, and the rightchoice of sugarcane hybrids are potential means of increasing irrigation water use efficiency (IWUE), water productivity (WP), and global water security. With the objective of optimizing irrigation water use, afield experiment evaluating the physiological efficiency of commercial sugarcane hybrids for WP in a sandy clay soil under water-limited conditions was conducted during 2016-2017 at the ICAR-Sugarcane Breeding Institute in Coimbatore, India. The replicated field experiment was laid out in split-plot design mth three irrigation levels as the main plot and 33 sugarcane hybrids as subplots. The prevailing climatic conditions during the experiment represented a tropical wet and dry climate, with the wet season lasting from October to December due tothe northeast monsoon. The results showed that full irrigation at recommended intervals with 100% crop evapotranspiration (ET) replacement (I_0) produced significantly higher cane yield than deficit irrigation at recommended intervals with 50% crop ET replacement (I_1) and skipping alternate irrigations with 50% crop ET replacement (I_2). The deficit irrigation treatments (I_1 and I_2) had declines in cane yield of 41.2% and 56.4%, respectively. IWUE yvas similar in Io andh, while I_2 had reducedIWUE by 23%. WP was significantly influenced by irrigation level; reduction in irrigation water reduced WP by 17.5% and 36.3% in I_1 and I_2 compared to Io. Among sugarcane hybrids, Co 85019, Co 13006, Co 10026, Co 99004, CoLk 8102, Co 86249, Co 8371，Co 94008, and Co 95020 yielded higher than the genotypic mean under both deficit irrigation treatments, suggesting their usefulness in deficit irrigation strategies. Sugarcane hybrids with high WP can play a pivotal role in sustaining sugarcane productivity andcan reduce the large volumes of irrigation water consumed in water-scarce tropical India. Thus, considering water security.，the implications of the results are of paramount importance in promoting the coordinated development and management of yvater, land, and related resources to maximize economic benefits and social welfare in an equitable manner without compromising the sustainability of vital ecosystems at local as well as national levels.