Root Length and Diameter at Flag Leaf Stage Correlate with Important Yield Parameters in Corn (Zea mays L.) Grown in Alkaline Soil Under Drought Conditions

Root growth and development are critical in determining corn yield, with nutrient and energy demands at a higher level during flag leaf stage. To simulate common abiotic stresses, an experiment was conducted under alkaline and drought conditions, which often limit root and shoot growth, nutrient uptake, and productivity. A randomized complete block design was used to evaluate the relationship between root length, root diameter, shoot growth, and yield components at the flag leaf stage. The results showed that grain yield had no relationship with shoot development but showed a strong positive correlation with nodal root length and diameter. Ear height (EH), ear weight (EW), unshelled weight (UW), shelled weight (SW), ear length (ER), and computed yield (CY) are strongly correlated with root length at r = 0.741, r = 0.578, r = 0.591, r = 0.869, and r = 0.874, respectively. Moreover, ear height, ear weight, unshelled weight, shelled weight, ear length, and computed yield are strongly correlated positively with the root length at r = 0.725, r = 0.831, and r = 0.822, r = 0.625, r = 0.408, and r = 0.622, respectively. These results indicate that nodal root length and thickness at the flag leaf stage are major determinants of eventual corn yield. The study emphasizes the importance of improved management practices to enhance root and shoot development during the flag leaf stage. It further suggests that breeding programs should focus on nodal root length and diameter, particularly under alkaline soil and drought conditions.