Root architectural variation in maize genotypes in response to phosphorus availability

Phosphorus (P) is very immobile and limited in calcareous soils due to its precipitation with calcium to form insoluble compounds and plants have to struggle a lot to increase its uptake. Pakistani soils are alkaline and calcareous in nature where maize growth is decreased by P deficiency. Modifications in root architecture may have better impact on P uptake by plants. To investigate the genotypic variation regarding root architecture and P uptake by maize, a rhizibox experiment was carried out in wire-house at Institute of soil and environmental sciences, University of Agriculture Faisalabad. The experiment was laid out in completely randomized design (CRD) using two treatments P0 (no phosphorus) and P1 (recommended phosphorus) with four replications. Maize genotypes, Faisalabad Maize, S-2002, Maize-2018, DTC-46 and EV-77 were sown in rhizobox. Seven days after the germinated seeds, plants were harvested and plant shoot and root fresh weight, as well as dry weight was measured. Maize roots were scanned and the primary root length, number of lateral roots, lateral root density, number of seminal roots and seminal root length of each plant was measured at low and sufficient P. Image-J software was used to determine the root architectural traits. Phosphorus was determined in shoot and root using spectrophotometer after digesting plant samples. At low level of P the number of lateral roots, number of seminal roots and seminal root length showed differential response among various genotypes and were increased in some genotypes. The primary root length decreased at low level of P. Lateral root growth increased the P uptake in P deficient condition may be due to search for P. Root architectural variation in response to P availability varies among maize genotypes where Maize-2018 and Faisalabad Maize showed better response to P availability regarding root architecture. Interestingly, number of lateral roots showed significant correlation with fresh shoot weight in all genotypes.