Natural variation for root traits and biomass partitioning under water stress in maize (Zea mays L.)

The present study reports the natural variation for root traits and biomass partitioning under water stress in maize. Highest and lowest rooting depth under irrigated and water stressed conditions was recorded for KDM-913A (140.75 cm) and KDM-361A (103.25 cm) respectively, while as under drought conditions the rooting depth ranged from 69.25 cm (KDM-913A) to 115 cm (KDM-912A and H17). Root volume under irrigated condition ranged from 40 ml (KDM-372) to 142.50 ml (H17) and under drought the lowest (22.50 ml) and highest (55.0 ml) root volume was recorded for KDM-372 and KDM-935A respectively. Under irrigated conditions highest root biomass was recorded for H17 (129.50 g) and the lowest value was recorded for KDM-372 (45.0 g), while as under drought the highest (55.0 g) and lowest (22.5 g) root biomass were recorded for KDM-935A and KDM-372, respectively. Highest shoot biomass under irrigated condition was recorded for H-17 (307.50 g) and the lowest was recorded for KDM-361A (149 g). However, under drought, the range of shoot biomass was from 28.0 g (KDM-361A) to 143 g (KDM-935A). The highest allocation of roots to total biomass under irrigated conditions was recorded for KDM-362B (41.31%) and the lowest for KDM-1051 (25.602%). While as under drought, the lowest (25.761) and highest (54.403) proportion of root biomass allocation was recorded for KDM-935A and KDM-463 respectively. The root: shoot ratio under irrigated condition was highest for KDM-361A (0.716) and lowest for KDM-372 (0.210), whereas under stress, the highest and lowest values were recorded for KDM-463 (0.91) and KDM-372 (0.36) respectively. Water stress caused greatest decrease in shoot biomass (68.87%) whereas lowest decrease was recorded for shoot to total biomass (9.59%). However, there was increase in root-shoot ratio (35.15%) and root to total biomass (23.80%) under water stress.