Luo Lijun

Water-saving and drought-resistance rice and its development strategy

Water-saving and drought-resistance rice (WDR) is a new type of rice with not only high yields and good quality, but also water-saving and drought-resistance characteristics. When this crop is irrigated, its grain yields and quality are equivalent to those of paddy rice, but its water requirement is only half that of paddy rice. It retains good yields in uplands because of its drought resistance. Furthermore, the sowing and cultivation of this rice requires lower inputs and less energy, and thus, it is very environmentally friendly. Here, we summarize the physiological and genetic mechanisms of water saving and drought resistance in WDR varieties, and the achievements in WDR breeding and genetics in the past decade. We discuss: 1) drought avoidance and drought tolerance, both of which improve yields under drought stress; 2) methods to evaluate drought resistance that have been used in breeding programs; 3) analysis and discovery of drought-resistance gene resources; and 4) analysis of the molecular mechanism of WDR in WDR varieties.

Hybrid rice and Green Super Rice

Rice is the most important staple food that feeds more than half of the world’s population, particularly in Asia where 90% of rice is consumed. Increasing rice production is essential to meet the demands of a growing human population, with its rising living standards. To address the demand, rice breeders seek new sources of genetic variation and strategies for efficient breeding to enhance the productivity, sustainability and resilience of rice varieties. Over the past sixty years, rice yield has undergone two big leaps, mainly due to the widespread utilization of semidwarf varieties and the exploitation of heterosis by developing hybrid rice. The increase of rice production has made great contributions to global food security. To further increase the yield potential, several approaches such as modification of plant architecture and exploitation of hybrid vigor between the subspecies indica and japonica have been successfully used in development of high-yielding varieties of rice. However, the increased food production with high-yield cultivars requires high-inputs of nutrient, water and labor. Excessive uses of fertilizers, insecticides, and water have resulted in severe problems such as the deterioration of soil, water and environment, as well as the decline of crop productivity. There is a massive challenge as increasing crop production must be achieved in a sustainable manner from less land and reduced inputs. To achieve continuous enhancement of crop production in a sustainable manner, “Green Super Rice” (GSR) with “less input, more production and better environment” was proposed as a new goal for rice breeding and rice production. The concept of GSR focuses on promoting resource saving and environment friendly rice production, while still achieving yield increase and quality improvement. Thus, the new rice varieties should possess the following characteristic: resistances to major insects and diseases in various rice producing regions, improved nutrient-use efficiency, and resistances to drought and other stresses in areas needed. Furthermore, GSR is not only a kind of varieties with the above desirable traits, but also advocates an efficient and environment-friendly crop management. Recently, tremendous achievements have been made in developing and adoption of the GSR cultivars by integrating gene resources, molecular and genomic tools, traditional and molecular breeding strategies, and combined with the application of improved agronomic practices, such as the mechanization and simplification of crop management. The GSR strategies and practices have influenced the prioritization of agricultural research direction and breeding targets, and the policy change for agricultural sustainability in China.