This study used the rice cultivar Suijing 18 to investigate the effects of morphological characteristics, photosynthetic changes, yield, as well as nitrogen absorption and utilization. The interaction between seeding rate and nitrogen rate was also assessed to identify the most suitable values of the dominant population for both factors under dry cultivation. Furthermore, the photosynthetic physiological characteristics of the upper three leaves in the dominant population were also explored. The results showed that a combination of 195 kg/ha seeding rate and 140 kg/ha nitrogen rate achieved high yield, high nitrogen utilization, and moderate morphological characteristics. This was achieved by a coordination of the combined advantages of population panicle number and spikelets per panicle. The photosynthetic potential of the population was improved by coordinating the reasonable distribution of light energy in the upper three leaves, which led to the emergence of a dominant rice population under dry cultivation.

Drought is a serious factor limiting rice production, and it leads to huge economic losses. Considering the current and projected global food demand, increasing productivity of drought-prone crops has become critical. In order to achieve the production target, rice drought-tolerant germplasm resources are an important prerequisite for the development of water-saving cultivation. Through multi-indicator measurement, the stress effect of drought on rice was clarified and a preliminary drought resistance identification index system was established based on the response of plant the germination, seedling and adult stages of rice and materials suitable for dry cultivation were screened. The results showed that relative root length, relative root weight and relative shoot weight were most affected by drought stress at the germination stage, while root length and root dry weight were positively correlated with the drought survival proportion at the seedling stage; high net photosynthetic rates and antioxidant enzyme activities are maintained in the late period in strongly drought-tolerant varieties. In this experiment, two drought-resistant varieties were screened, there was a high consistency in the screening of drought-tolerant varieties at the germination and seedling stages, with their joint screening showing the same performance as at the adult stage. The drought-resistant varieties at the adult stage can promote seed filling and ensure group yield by prolonging photosynthesis time and enhancing antioxidant enzyme activity, which can provide theoretical support and material basis for future variety screening and evaluation, as well as rice dry-crop cultivation.

The conflict between rice production and water scarcity is becoming more pronounced. Therefore, the advancement of water‐saving rice cultivation is crucial in guaranteeing both food and ecological security. This study provides a summary of the development and characteristics of various water‐saving cultivation techniques for rice, including alternate wetting and drying irrigation, wet irrigation, controlled irrigation, the system of rice intensification, direct seeding rice, and dry cultivation of rice (DCR). We also introduce the varietal characteristics of upland rice, aerobic rice, water‐saving and drought‐resistant rice, and DCR. We summarize the impact of different water‐saving cultivation models on yield and quality and regulatory measures, and propose challenges and strategies for the development of water‐saving cultivation of rice in the future. We hope to provide a reference for promoting the development of rice water‐saving cultivation and dry farming agriculture.

The production efficiency of water and nitrogen is affected by irrigation and the nitrogen rate. However, it is unclear whether there is a coupling effect of irrigation mode and the timing of nitrogen fertilizer application on rice. Therefore, a two‐year field experiment was conducted at two sites with varying cumulative temperatures from 2018 to 2019. The effects of irrigation mode and nitrogen fertilization timing on rice yield and related physiological parameters were examined in different regions. The results showed that sites with different average temperatures had different coupling effects of water and nitrogen on crop growth. The impact of irrigation mode on yield was greater than that of nitrogen fertilizer timing at the site with a 2800 °C annual cumulative temperature (Wanchang). Alternate wetting and drying irrigation increased yield, water production efficiency and nitrogen production efficiency by 8%–10%, 31%–37% and 8%–10%, respectively. In the site with a 2500 °C annual cumulative temperature (Longjing), the coupling effect of irrigation method and nitrogen fertilization timing was significant, and continuously flooded irrigation combined with nitrogen fertilizer (40%:30%:20%:10%) improved rice yield and production efficiency by delaying senescence of leaves and increasing dry matter translocation. The results indicate that combining temperature to explore the optimal coupling mode of irrigation and nitrogen is a promising cropping technique to improve crop productivity and production efficiency in northeastern China.

In order to study the application of light and simplified cultivation mode in straw returning field. In the experiment, two treatments of straw returning and non-straw returning were used under the light simplified cultivation mode, and the differences of tiller number, dry matter accumulation, leaf area index, chlorophyll and yield were studied. Field cultivation experiments were carried out with Jihong 9 and Jinongda 138. The results showed that the yields of Jihong 9 and Jinongda138 straw returning to the field under the light and simplified cultivation mode were 2.00% and 3.63% higher than those under the non-straw returning mode. The total grain number in the yield components increased by 3.35% and 11.60% respectively. Dry matter increased by 19.70% and 7.66% in mature period. The leaf area index (LAI) and SPAD value in the later period of straw returning were higher than those in the non-straw returning, and the number of effective tillers was lower. Light and simplified cultivation can be used as a new mode of rice high-yield cultivation under straw returning, which improves the total grain number, leaf area index, SPAD value and dry matter in the later stage, and increases rice yield. The yield advantage of Jinongda 138 under straw returning (SJ138) is more significant.