Soil Water Effect on Root Activity, Root Weight Density, and Grain Yield in Winter Wheat

Soil water has a significant effect on root characteristics, influencing overall growth. Understanding the optimal timing, depth, and volume of irrigation is important. Two years of field experiments were conducted to determine the effect of soil water content on root activity, root weight density, and yield in winter wheat (Triticum aestivum L.). Six water treatments (W) were applied: W1 [35–45% field water capacity (FC)], W2 (45–55% FC), W3 (55–65% FC), W4 (65–75% FC), W5 (75–85% FC), and W6 (85–95% FC). Soil samples were collected at depths of 0 to 20 cm (Layer 1, L1), 20 to 40 cm (Layer 2, L2), and 40 to 60 cm (Layer 3, L3) at 58, 110, 147, 177, 199, 206, and 217 d after sowing (DAS). Irrigation to maintain soil water content at 65 to 75% FC resulted in the highest root activity and root weight density, with the highest value at 177 DAS (flowering). Root activity and root weight density were highest in L2. Growth stage and soil water had a significant effect on root activity and root weight density; soil layer also had a significant effect on root weight density. Root activity and root weight density were closely related to grain yield. Associations with grain yield showed a stronger relationship with yield at later rather than early stages. The findings suggest that the optimal irrigation to promote root activity and root weight density in wheat was 65 to 75% of FC at 20 to 40 cm.