Evaluation of supplemental irrigation in cotton based intercropping system in rainfed vertisols of north western zone of tamil nadu

Abstract

newlineA field trial was carried out at farmer s field of Thittacheri, Salem district during newline2017-18 and 2018-19 to evaluate the supplemental irrigation for cotton based newlineintercropping system under rainfed Vertisols in North Western Zone of Tamil Nadu. newlineThe field experiment was laid out in strip plot design with three replications. The main newlineplot consisted of no supplemental irrigation (control) (SI0), supplemental irrigation at newlinevegetative stage (2-4 weeks) (SI1), supplemental irrigation at squaring and flowering newlinestages (5-8 weeks) (SI2), supplemental irrigation at boll development stage (9-13 weeks) newline(SI3), supplemental irrigation at vegetative, squaring, flowering and boll development newlinestages (2-13 weeks) (SI4) and supplemental irrigation at appearance of wilting symptom newline(SI5). Cotton alone (IC0), cotton + blackgram (1:3) (IC1), cotton + clusterbean (1:3) (IC2) newlineand cotton + coriander (1:4) (IC3) were imposed in intercropping system of subplot. newlineThere was no variation in germination percentage of cotton in both years of study. newlineTaller plants (116.1 cm) and higher LAI (3.6) were recorded in supplemental irrigation at newlineappearance of wilting symptom at 120 DAS. Among intercropping system treatments, newlinetaller plants of 136.6 and 114.6 cm and higher LAI of 4.0 and 3.4 was recorded in cotton newlinealone at 120 DAS during 2017-18 and 2018-19, respectively. During 2017-18 in newlineintercropping system, higher RGR was recorded in cotton alone and was on par with newlinecotton + blackgram (1:3) at 30-60 DAS but at 60-90 and 90-120 DAS, higher RGR was newlineobserved in cotton + clusterbean (1:3) and cotton + coriander (1:4). With respect to newlinesupplemental irrigation treatments, supplemental irrigation at appearance of wilting newlinesymptom recorded higher CGR of 2.46 g/m2 newline/day and relative growth rate value newline(6.7 mg/g/day) of cotton during second year of research (2018-19) at 120 to harvest stage. newlineDuring 2017-18 and 2018-19 of study, cotton alone recorded higher CGR (0.98 and newline2.26 g/m2 newline/day) and RGR of cotton (2.1 and 6.4 mg/g/day) at 120