Optimizing groundnut sowing for minimizing dry spell risks over Rayalaseema, a rainfed region of India

Abstract

Groundnut productivity in rainfed regions of arid and semi-arid agro-ecosystems in southern India is highly vulnerable to intra-seasonal rainfall variability as well as the timing, duration, frequency, and intensity of dry spells. The Rayalaseema semi-arid region of India, a major groundnut (Arachis hypogaea L.)-growing region, has experienced increasing intra-seasonal rainfall variability, especially over the last few decades. To understand the impacts of dry spells on the growth and development of groundnut, field experiments on groundnut (cultivar K6) were conducted at the Agricultural Research Station, Ananthapuramu, Andhra Pradesh, during 2015–2020. The results indicated that the amount and distribution of rainfall during different phenophases were the most influential parameters on dry matter production, phenology, and pod yield in groundnut and can have either a positive or negative effect depending on whether the rainfall matches the crop's water requirements during specific growth stages. It was found that, in July second fortnight (II-FN) sown crop, the rainfall received was synchronized with pod initiation to maturity stage, resulting in higher dry matter production (456 g m⁻²) and pod yield (1123 kg ha⁻¹). On the other hand, pod initiation-pod maturity stage with August I-FN sown crop received less rainfall, leading to a soil moisture deficit and lower pod yields (815 kg ha⁻¹). The duration of pod initiation-pod maturity stage with August I-FN sown crop was significantly less (47 days) compared to July II-FN (54 days) and July I-FN (50 days) sown crops, resulting in reduced pod filling period that drastically affected pod yield. It can be concluded that the existing sowing time for groundnuts needs to be advanced from August I-FN to July II-FN. This will not only avoid terminal moisture stress during pod initiation-pod maturity stage but also help in enhancing groundnut productivity in rainfed areas of Rayalaseema region.