EFFECTS OF WATER STORAGE IN DEEPER SOIL LAYERS ON GROWTH, YIELD, AND WATER PRODUCTIVITY OF COTTON (GOSSYPIUM HIRSUTUM L.) IN ARID AREAS OF NORTHWESTERN CHINA

In order to understand how the available water stored prior to planting (ASWp) affects cotton yield and the relative physiological parameters, we designed two ASWp levels in columns, well-watered (P-90) and no watering (P-0), combined with different water management scenarios during the cotton-growing period, 70% of field capacity (FC) during the third leaf to boll opening stage (I-70) and changed the third leaf to flowering stage in 55% of FC and 80% of FC thereafter (I55-80). P-90 enhanced root length density (RLD), surface area density (RSD), and root activity, which in turn increased the efficiency of ASWp usage. A significantly higher leaf water potential, net photosynthesis rate, above-ground dry matter (DM), and yield were found in P-90 than in P-0. Under well-watered conditions, I55-80 had a higher RLD in the 40-120cm layer compared with I-70. However, root mass density (RMD) and DM in I55-80 were significantly decreased that led to marked decreases in yield and, to a lesser extent, in water productivity (WP). Under no watering conditions, yield and WP were significantly increased in I-70 relative to I55-80. It showed that sufficient water in deeper soil layers and a sustained 65-75% of FC could be an appropriate drip irrigation mode for the local cotton field. Copyright (c) 2013 John Wiley & Sons, Ltd.