Effect of moisture regimes on water use efficiency of Rabi/summer groundnut genotypes in northern transition zone of Karnataka

During rabi/summer irrigation water is a scarce resource, but crop needs more water due to non-rainy season and warmer climate. Hence, a field experiment was conducted during rabi/summer season of 2016–17 to study the effect of irrigation water regimes on water use efficiency (WUE) of groundnut genotypes in Northern Transition Zone of Karnataka.

This field study comprised of four main plots as water regimes viz. I,: (control) seven irrigations at 15 days interval from sowing to 105 DAS, I₂: Stress at pegging stage; withdrawal of one irrigation between 45 - 60 DAS, I₃: Stress at pegging and pod filling stage; withdrawal of two irrigations between 45–75 DAS, I₄: Stress at pegging, pod filling and kernel development stage; withdrawal of four irrigations from 45–105 DAS and four genotypes as sub plots viz. G₁: Dh-86, G₂: Dh-101, G₃: K-9 and G₄: G2–52. Treatments were replicated thrice and laid out in split plot design.

Among the water regime, I₂ recorded significantly higher WUE (6.2 kg ha⁻¹ mm⁻¹) followed by I₁ (control; 5.5 kg ha⁻¹ mm"¹). Water regime I₂ also recorded significantly higher pod yield and haulm yield (2,857 kg ha⁻¹; 4,648 kg ha⁻¹, respectively) along with other yield attributes, but was found at par with control (I₁). This study showed that WUE as well as yield of rabi/summer groundnut can be enhanced if crop was exposed only to mild stress by skipping an irrigation at pegging stage out of total seven irrigations. Among the genotypes, Dh-86 with 2,375 kg ha⁻¹ of pod yield performed significantly better over others like Dh-101 (2,215 kg ha⁻¹), K-9 (2,048 kg ha⁻¹) and G2–52 (1,880 kg ha⁻¹) suggesting differential response to moisture stress, thus choice of moisture stress tolerant genotypes is equally important to enhance WUE. Interaction between irrigation regime and genotypes showed that Dh-86 (G₁) with I₂ irrigation regime recorded significantly higher WUE (6.9 kg ha⁻¹ mm⁻¹), pod yield (3,168 kg ha⁻¹) and net return (Rs. 95,655 ha⁻¹) and was found at par with full irrigation regime (I₁).