Effects of soil water on maize root morphological and physiological responses to phosphorus supply

Abstract

AbstractWater shortage directly constrains plant growth and survival, and indirectly influences plant responses to soil mineral nutrients, especially low‐mobility nutrients such as phosphorus (P). We examined the effects of soil water content on the responses of agronomic and root morphological and physiological traits of maize (Zea mays L. cv. NE15) to P supply. Seven P supply levels (0, 12.5, 25, 50, 75, 100, and 300 mg P kg−1 soil) and two water regimes (well watered, WW; water stress, WS) were employed. Shoot dry weight, root dry weight, and root length were enhanced with the increase of P supply rates, while the root : shoot ratio, specific root length, and transcription levels of four inorganic phosphate (Pi) transporter genes (Pht1;1–4) declined with the increase of P supply rates. Under WS conditions, root dry weight and root length decreased by 4–38% and 6–32%, respectively, compared to the WW treatment, whereas the root : shoot ratio and specific root length increased by 7–33% and 8–28%, respectively. Pi transporter gene transcription was up‐regulated and that of the arbuscular‐mycorrhizal‐induced transporter (Pht1;6) gene was both up‐ and down‐regulated in response to the WS treatment. Comprehensive analysis revealed that interaction between maize root morphological and physiological traits was stimulated as a strategy for efficient P acquisition under WS conditions. This study is the first to use both morphological and physiological traits to describe the impacts of soil water conditions on maize responses to P fertilization. Our results provide valuable information for optimization of P management under different soil water conditions.