Maize root architecture response to phosphorus availability in rooting medium

Abstract

Phosphorus (P) is precipitated with calcium (Ca) in calcareous soil very quickly, thus very immobile in the soil with restricted availability to plants for uptake by plant roots. Therefore, Pakistani soils are limiting maize growth due to P deficiency. Root architectural alteration can influence P accessibility and uptake by maize plants. Constitutive and P-deficiency-induced alterations in the root architecture of maize were investigated through a rhizobox study carried out in a net house during the maize growing season under natural climatic conditions. In the first treatment, P was deficient, whereas in the second treatment, the recommended amount of P fertilizer was applied to maize with four replications for precise results. Maize varieties named Faisalabad Maize, S-2002, Maize-2018, DTC-46, and EV-77 were sown in sand-filled rhizobox. Plants were harvested after seven days of germination, and plant shoots and roots were measured. Maize roots were scanned to digitalize the image to study root system architecture using Image-J software. Primary root length, number, and density of the lateral root of each seedling were measured at low and sufficient P. Primary root length decreased to a low level of P in the rooting medium. Root architectural variation in response to P availability differs among maize varieties because Maize-2018 and Faisalabad maize showed improved responses to P availability regarding root architectural traits. Interestingly, LRN showed a significant increase and correlation with the growth parameters of all cultivars under P-deficient conditions. Therefore, it is concluded that varieties with more lateral roots can tolerate P-deficient conditions in a better way, and such characteristics may be incorporated into future breeding programmes.