Fiber quality, oil seed composition and fatty acid profiling of cotton (Gossypium hirsutum L.) seed as influenced by sub-surface drip-irrigation and foliar-fertilization strategy in semi-arid agro-ecology of south-Asia

Under climate-change, micro-irrigation practices like sub-surface drip-irrigation (SSDI) coupled with optimized-fertigation and foliar-nutrition, may improve crop-productivity and quality. Hence, current study in cotton ( Gossypium hirsutum L.) comprised of three SSDI-regimes [60, 80, 100 % ET c ], two N-fertigation levels [80, 100 % RDN] and two nutrient-application methods [foliar-spray of KNO 3 & MgSO 4 (M foliar ) versus fertigation (M fert )] in factorial randomized-complete-block-design besides three additional controls (surface-drip + N 100 + M foliar ; surface-drip + N 100 + M fert ; flood-irrigation + soil RDN + M foliar ). The results indicated that SSDI at 80%ET c enhanced seed-cotton-yield by ∼5.3 and 9.9 %, ginning out-turn (GOT) by ∼2.1 and 4.8 %, fiber-length by ∼5.7 and 7.6 %, lint-index by ∼5.8 and 11 % and protein-yield by ∼7.8 and 11.6 %, over 60%ET c in 2019 and 2020. Oil-content, oil-yield, cake-content, and cake-yield varied significantly with increased irrigation from 60 to 100%ET c , underscoring the importance of adequate water for oil-synthesis in cottonseeds. Fatty-acid composition was sensitive to irrigation-levels, with significant reduction in saturated-fatty-acid (SFA) and unsaturated-fatty-acid (UFA) by ∼5.4 and 5.5 %, and monounsaturated-fatty-acid (MUFA) and polyunsaturated-fatty-acid (PUFA) by ∼2.9 and 5.9 % at 60%ET c over 80%ET c during 2019 and 2020, respectively. Polyunsaturated:saturated (P/S) index, vital for human cardio-vascular health, increased by ∼5.2 and 7.1 % under 60%ET c . To harness higher yield with better quality fiber, protein, oil-yield and cottonseed-cake, SSDI at 80%ET c proved optimal, with no-additional benefits beyond this level. Enhancing fertigation from 80 to 100%RDN slightly enhanced UFAs and reduced SFAs. Higher UFAs is desirable for reducing low-density lipoprotein (LDL) cholesterol-levels. Foliar-spray of KNO 3 & MgSO 4 enhanced GOT, lint-index, UFAs, MUFA:PUFA and P/S index over fertigation. SSDI improved both fiber and seed-composition over flooding. Overall, SSDI at 80%ET c , combined with fertigation at 80%RDN and foliar-fertilization offers substantial benefits for cotton-productivity and quality in water-scarce agro-ecologies. These practices improve water-use-efficiency and sustainability, hence, enhancing resilience and economic-viability of cotton-industry amidst environmental-challenges. • SSDI at I 80 with N 80 and M foliar increased SCY (∼12.3 %) & CSY (∼9.14 %) over flood-irrigation (FI). • I 80 with F 80 & M foliar enhanced MUFA, PUFA & SFAs while saving ∼20 % water & nutrients. • I 60 with N 100 and M foliar enhanced P/S index (7.2 %) over I 80 with N 80 and M foliar . • Higher fiber-quality, oil yield (19.2 %) and protein yield (14.9 %) under I 80 with N 80 and M foliar over FI.