Water and Nitrogen Effects on the Growth and Yield of Spring Wheat

To study the combined effects of controlled water and nitrogen supplies on growth and yield of spring wheat (Triticum aestivum L.), plants were grown in a controlled environment chamber during the entire growth period. When the 3rd leaf was visible, three levels each of water and nitrogen supply, for a total of nine treatments, were applied using the system to accurately control soil water and nitrogen levels. There was a significant interaction of water and nitrogen levels on growth and yield of wheat. Under low water conditions few tillers were produced and the biomass production and grain yield were suppressed, whereas nitrogen supply level had little impact on the plants. With increasing water supply, on the other hand, the production of tillers, biomass and yield increased significantly. Furthermore, the nitrogen supply level had significant effects on growth and yield as the water stress decreased. Water and nitrogen shortages caused increases in phyllochron values. However, heading of the main stem was almost unchanged because of the compensation by a decreased number of leaves on main stem. The impact of water and nitrogen stresses on growth and yield was reflected primarily by the strong response of tillering at the individual plant level.