Efficient utilization of light and heat resources is an important part of cleaner production. However, exploring the changes in light and heat resources utilization potential in paddy under future climate change is essential to make full use of the potential of rice varieties and ensure high-efficient, high-yield, and high-quality rice production, which has been seldom conducted. In our study, a process-based crop model (CERES-Rice) was calibrated and validated based on experiment data from the Songnen Plain of China, and then driven by multiple global climate models (GCMs) from the coupled model inter-comparison project (CMIP6) to predict rice growth period, yield, and light and heat resources utilization efficiency under future climate change conditions. The results indicated that the rice growth period would be shortened, especially in the high emission scenario (SSP585), while rice yield would increase slightly under the low and medium emission scenarios (SSP126 and SSP245), it decreased significantly under the high emission scenario (SSP585) in the long term (the 2080s) relative to the baseline of 2000–2019. The light and temperature resources utilization (E_RT), light utilization efficiency (E_R), and heat utilization efficiency (HUE) were selected as the light and heat resources utilization evaluation indexes. Compared with the base period, the mean E_RT in the 2040s, 2060s, and 2080s were −6.46%, −6.01%, and −6.03% under SSP126, respectively. Under SSP245, the mean E_RT were −7.89%, −8.41%, and −8.27%, respectively. Under SSP585, the mean E_RT were −6.88%, −13.69%, and −28.84%, respectively. The E_R would increase slightly, except for the 2080s under the high emission scenario. Moreover, the HUE would reduce as compared with the base period. The results of the analysis showed that the most significant meteorological factor affecting rice growth was temperature. Furthermore, under future climate conditions, optimizing the sowing date could make full use of climate resources to improve rice yield and light and heat resource utilization indexes, which is of great significance for agricultural cleaner production in the future.

Humic acid fertilizer (HA) incorporation is a common method for improving crop growth and soil fertility. However, the effects of HA incorporation on rice growth are still unknown. We conducted a two-year field experiment to determine the radiation use, growth, and yield of rice grown with five different HA rates: 110 kg∙ha⁻¹ 100% urea (pure nitrogen) (T1); 30% HA and 70% urea (T2); 50% HA and 50% urea (T3); 70% HA and 30% urea (T4), and 1500 kg∙ha⁻¹ 100% HA (T5). The results showed that the T2 treatment had the lowest values of photosynthetic efficiency of PSII (F_v/F_m), relative leaf chlorophyll content (SPAD), plant height and leaf area index (LAI) in both years, which were similar to the photosynthetically active radiation (IPAR), radiation use efficiency (RUE), yield, and biomass. In contrast, the highest harvest index (HI) value was found in the T2 treatment. In the two years, the T4 and T5 treatments showed no significant differences. However, the multivariate statistical method based on principal component analysis showed that in the first principal component, the LAI, biomass, yield, plant height, SPAD, F_v/F_m, IPAR, and RUE had a positive correlation, and the HI had a negative correlation. The LAI, yield, plant height, SPAD, HI, and RUE had a positive correlation, but biomass, F_v/F_m and IPAR had a negative correlation in the second principal component. Across the different HA treatments, the comprehensive scores were T5 > T4 > T3 > T1 > T2, with values of 2.13, 1.38, −0.17, −0.34, and −3.00, respectively. According to the principal component analysis results of each index, the T5 treatment was better than the T4 treatment.

To optimize a suitable fertilization method needed for high nitrogen utilization and growth of mung bean in the black soil of Northeast China, a field experiment was carried out with 10 treatments based on isotope-tracing technology. The nitrogen fertilizer utilization, residual, loss and dry-matter transportation, leaf area, photosynthetic potential, and wet-basis moisture content of mung bean were discussed. The results showed that the total utilization rate of nitrogen fertilizer under different treatments was 34.75~47.71%, while in the 0~15 cm soil layer, the total residual rate was 11.36~33.69%, and the loss rate was 21.03~53.89%. The T1 treatment had the lowest total nitrogen fertilizer utilization rate and the greatest loss rate. The leaf area and photosynthetic potential at the seedling stage in the T9 treatment, the branching stage in the T2 treatment, and the flowering stage in the T4 and T9 treatments were 5.11~31.82% higher than those in the CK treatment, and the values at the drumming and maturing stages were significantly lower than those in the CK treatment (p < 0.05). The total wet-basis water content of the root, stem, leaf, and pod in the whole stages compared with the CK treatment increased by 3.35~7.41% in T4, T5, T7, and T8. In the T6 and T9 treatments, the output rate of stem-sheath storage matter and the transformation rate were significantly higher than those in the T1 treatment (p < 0.05). The dry-matter accumulation in the T1 and T9 treatments was significantly different from that in the CK treatment, which increased by 27.72% and 5.10%, respectively. Thus, organic fertilizer coupled with nitrogen fertilizer can improve the nitrogen fertilizer utilization rate and the growth of mung beans.