Effect of Weed Management Practices on Growth, Yield and Quality of Spring Planted Sugarcane–Based Intercropping System

Abstract

Spring-planted sugarcane is vulnerable to early weed competition because of its slow initial growth and wide row spacing, while short-duration intercrops may improve system productivity and returns. A three-year field experiment was conducted at the Main Sugarcane Research Station, Junagadh Agricultural University, Kodinar, Gujarat, India, from 2013–14 to 2015–16 to assess the influence of summer intercrops and weed-control practices on the growth, yield, quality, weed dynamics and economics of spring-planted sugarcane. The experiment was laid out in a split-plot design with three replications, comprising five cropping systems as main plots [sole sugarcane; sugarcane + summer green gram (1:1); sugarcane + summer black gram (1:1); sugarcane + summer groundnut (1:2); sugarcane + summer sesame (1:1)] and three weed-control treatments as subplots [unweeded control; two hand weedings at 20 and 40 days after sowing of the intercrop; pendimethalin 30 EC @ 0.90 kg/ha pre-emergence + one hand weeding at 30 DAS of the intercrop]. Pooled analysis showed that cane yield, growth parameters and yield attributes, including germination percentage, stalk diameter, single cane weight and number of millable canes, were not significantly affected by the different intercropping systems, except for millable cane height. However, cane equivalent yield was significantly higher under sugarcane + sesame (118.16 t/ha), sugarcane + green gram (117.85 t/ha) and sugarcane + black gram (114.78 t/ha) compared with sole sugarcane (99.86 t/ha) and sugarcane + groundnut (100.61 t/ha). Juice-quality parameters (Brix, sucrose, purity, CCS and extraction percentage) and weed parameters (weed density at 30 DAS and at harvest, and weed dry matter at harvest) were not significantly influenced by the intercropping systems. In contrast, weed-control measures markedly improved crop performance. Both two hand weedings at 20 and 40 DAS and pendimethalin 0.90 kg/ha pre-emergence + one hand weeding at 30 DAS significantly increased millable cane height, single cane weight, number of millable canes and cane yield compared with the unweeded control. These treatments also produced significantly higher cane equivalent yields (132.55 and 132.03 t/ha, respectively) than the unweeded control (66.17 t/ha). Juice-quality parameters (Brix, sucrose, CCS, extraction percentage and commercial cane sugar) were significantly improved by these weed-control practices, except for purity percentage. Weed-control efficiency was highest with two hand weedings (75.26%) and pendimethalin + one hand weeding (73.96%). Economically, the sugarcane + sesame (1:1) system recorded the highest net return (₹146,466/ha) and benefit:cost ratio (2.26), closely followed by sugarcane + green gram (₹145,257/ha; B:C 2.24) and sugarcane + black gram (₹139,740/ha; B:C 2.21). Among weed-control options, two hand weedings and pendimethalin + one hand weeding gave the highest net returns (₹169,160/ha and ₹168,969/ha) and B:C ratios (2.35 and 2.36), respectively, compared with the unweeded control. The study indicated that integrating summer legume intercrops, particularly sesame, green gram or black gram, with effective early-season weed management can enhance the productivity and profitability of spring-planted sugarcane without compromising juice quality.