Effect of lateral spacing and irrigation level on growth and physiological parameters of aerobic rice (Oryza sativa L.) under subsurface drip irrigation

Abstract

The study was conducted during the summer season (February-May) 2025 at SRM College of Agricultural Sciences, to evaluate the effect of subsurface drip irrigation (SSDI) on growth parameters of aerobic rice (Oryza sativa L.) growth, under different lateral spacings (45,60 and 75 cm) and irrigation levels 100% ETc and 125% ETc against surface drip irrigation and conventional method (transplanted) in rice cultivation. Transplanted rice consistently outperformed other treatments in all growth parameters plant height (27.90 and 58.59 cm), number of tillers per m2 (277 and 443), dry matter production (2503 and 7509 kg/ha) at 30 and 60 DAS. The result showed significant difference between the treatments. Among the subsurface drip irrigation, irrigation at 125% ETc with lateral spacing (T4) recorded tallest plant height (26.10 and 54.81 cm), higher number of tillers (262 and 420 no./m2), dry matter production (2364 and 7093 kg/ha) at 30 and 60 DAS respectively. The treatment T4 shown higher leaf area index (1.43 and 4.00) and SPAD values (35.58 and 46.25) indicating enhanced photosynthetic efficiency. These results show SSDI with a 45 cm spacing and 125% ETc irrigation surplus is the most effective configuration for aerobic rice system which optimizes water use and boosts productivity making it ideal for cultivating rice in water-limited environments. By supporting high yields without traditional flooding, SSDI with 45cm spacing with 125%ETc offer strong experimental support for adopting SSDI in tropical rice-growing regions under climate-change stress.