Yield response, water productivity, and seasonal water production functions for maize under deficit irrigation water management in southern Taiwan

As the challenges toward increasing water for irrigation become more prevalent, knowledge of crop yield response to water can facilitate the development of irrigation strategies for improving agricultural productivity. Experiments were conducted to quantify maize yield response to soil moisture deficits, and assess the effects of deficit irrigation (DI) on water productivity (water and irrigation water use efficiency, WUE and IWUE). Five irrigation treatments were investigated: a full irrigation (I-1) with a water application of 60 mm and four deficit treatments with application depths of 50 (I-2), 40 (I-3), 30 (I-4), and 20 mm (I-5). On average, the highest grain yield observed was 1008.41 g m(-2) in I 1, and water deficits resulted in significant (p < .05) reduction within range of 6 and 33%. This reduction was significantly correlated with a decline in grain number per ear, 1000-grain weight, ear number per plant, and number of grain per row. The highest correlation was found between grain yield and grain number per ear. The WUE and IWUE were within range of 1.52-2.25 kg m(-3) and 1.64-4.53 kg m(-3), respectively. High water productivity without significant reduction in yield (<13%) for I-2 and I-3 compared to the yield in I-1 indicates that these water depths are viable practices to promote sustainable water development. Also, for assessing the benefits of irrigation practices in the region crop water production functions were established. Maize yield response to water stress was estimated as .92, suggesting the environmental conditions are conducive for implementing DI strategies.