An integrated irrigation strategy for water-saving and quality-improving of cash crops: Theory and practice in China

The cash crop industry has been developed extensively around the world, but in some cases high yields are obtained at the expense of large water and fertilizer input. Although the yield is higher under these practices, it may not be a high-efficient approach from the perspective of crop quality, economical revenue and sustainability in a long term. To solve this problem, an integrated high-efficient irrigation strategy for water-saving and quality-improving of cash crops (WSQI) has to be proposed. Here, we review the research frontiers in this field and the findings of our research group, aiming to expound WSQI with the following perspectives (1) Deficit irrigation under certain conditions and reasonable fertilization can significantly improve the quality of cash crops. Based on the screening of water/nutrient-sensitive quality traits, comprehensive evaluation methods combining the determination of weight for single quality attributes can be used to evaluate and compare comprehensive fruit quality index. (2) Statistical models of water-yield-quality for cash crops were developed that consider the compromise between crop yield and quality. The exploration of biophysical models revealed the mechanisms underlying crop quality formation. (3) Linear, non-linear, dynamic and multi-objective programming models can be powerful tools for supporting irrigation decision-making while considering crop water yield-quality relationships, market supply and demand, consumer preferences, crop price and resource availability. The integrated high-efficient irrigation strategy proposed in this review would motivate the transition of irrigation strategies from the conventional field irrigation theory, to a new chapter of irrigation management for water conservation and quality improvement in cash crops. The first one is based on water balance and water yield models, while the second one is based on the information of crop water demand and comprehensive consideration of the water-yield-quality relationship. In addition, this review will provide a theoretical basis and decision-making guidance for research innovation and agricultural production.