Rajkumara, S.Roopashree, M.2021-09-152021-09-152016-07https://krishikosh.egranth.ac.in/handle/1/5810175773A field experiment was conducted to study the response of Bt cotton to surface and subsurface drip irrigation with different ETc levels under vertisols at the Irrigation Water Management Research Centre, Belvatagi during kharif 2015-16. The irrigation methods were surface drip and subsurface drip irrigation and the ETc levels were 1.0, 0.8 and 0.6 along with control (surface irrigation @ 0.6 IW/CPE ratio) comprising six treatment combinations, replicated four times in split plot design. Subsurface drip irrigation gave numerically higher seed cotton yield (3,109 kg ha-1) which was 13 per cent higher than surface drip irrigation (2,748 kg ha-1). Among ETc levels, irrigation scheduled at 1.0 ETc recorded numerically higher seed cotton yield (2,996 kg ha-1). Subsurface drip irrigation with 1.0 ETc recorded significantly higher seed cotton yield (3,471 kg ha-1) over other treatment combinations and was on par with surface drip irrigation with 0.6 ETc (3,072 kg ha-1). These yield advantages are due to better growth, yield attributes and moisture content available during crop growth period. Surface irrigation with 0.6 IW/CPE ratio recorded significantly higher seed cotton yield (3,206 kg ha-1) over surface drip irrigation with 1.0 (2,521 kg ha-1) and 0.8 ETc (2,681 kg ha-1) and was on par with all other treatments. Similarly significant differences in growth parameters such as leaf area, leaf area index and total dry matter production were also noticed in the same set of treatment. Significantly higher soil moisture content was recorded in subsurface drip irrigation with 1.0 ETc during all growth stages. Surface drip irrigation with 0.6 ETc recorded significantly higher water use efficiency (7.06 kg ha-1 mm) over all other treatment combinations. Irrigation scheduled at 1.0 ETc along with subsurface drip irrigation recorded higher higher gross return (` 1,56,195/ha), net return (` 1,09,538 /ha) and B:C ratio (3.34)EnglishThesis