Root systems of peanut cultivars respond differently to soil P availability to improve P uptake

Abstract

BackgroundPeanut (Arachis hypogaea L.) is regarded as a crop with high nutrient use efficiency, but there may be differences between cultivars. Furthermore, there is little information on the strategy of peanut cultivars to adapt to soil P availability and to what extent they explore non‐labile P pools.AimsOur objective was to evaluate growth, root morphology, enzymatic activity in the rhizosphere, and P uptake of peanut cultivars grown under different soil P status.MethodsThe study was conducted in a greenhouse in 6‐L pots. Soils with low P (without fertilization) and high P content (with fertilization) and seven peanut cultivars of different origins, different maturation groups, and release years were investigated. Peanut shoot yield, phosphorus uptake, root growth, soil P fractions as well as phosphatase activity in the rhizosphere soil were determined.ResultsIn P‐deficient soil, a higher dry matter yield was associated with longer root hairs and root length, which resulted in decreased soil non‐labile P was observed mainly with cultivars developed in Argentina (ARG‐medium‐old and ARG‐medium‐new) and the late maturity Brazilian cultivar (BR I‐late new). These cultivars adapted well to P deficiency and were less dependent on labile P. New Brazilian early and medium maturity cultivars developed less, shorter root hairs, and showed low acid phosphatase activity in the rhizosphere under P deficiency, resulting in lower P uptake and dry matter yield. Under high P availability, new Brazilian cultivars of medium and late maturity showed the highest dry matter yield (9.0 and 9.8 g plant−1, respectively) and longest roots, around 120 m plant−1. High P availability decreased root hairs in all cultivars.ConclusionOverall, the adaptation of peanut cultivars to P‐deficient soils was lower for the new mid‐ and early‐maturing Brazilian cultivars compared with the Argentinian and old or late‐maturing Brazilian cultivars. The main strategies of P‐efficient cultivars under low P availability are to increase root length, root hair length, and root hair density.