Crop yield improvement is necessary to keep pace with increasing demand for food. Due to climatic variability, the incidence of drought stress at crop growth stages is becoming a major hindering factor to yield improvement. New techniques are required to increase drought tolerance along with improved yield. Genetic modification for increasing drought tolerance is highly desirable, and genetic engineering for drought tolerance requires the expression of certain stress-related genes. Genes have been identified which confer drought tolerance and improve plant growth and survival in transgenic wheat. However, less research has been conducted for the development of transgenic wheat as compared to rice, maize, and other staple food. Furthermore, enhanced tolerance to drought without any yield penalty is a major task of genetic engineering. In this review, we have focused on the progress in the development of transgenic wheat cultivars for improving drought tolerance and discussed the physiological mechanisms and testing of their tolerance in response to inserted genes under control or field conditions.

The nitrogen use efficiency (NUE) of modern maize hybrids has been greatly improved, but for decades, little was known on whether the NUE heterosis of maize hybrids had increased. A two-year field study was conducted on eight maize hybrids and their parental inbred lines from the 1970s to 2000s under two N levels (0, 150 kg N ha⁻¹). These were the most popular hybrids in China’s main maize-growing areas at the time. The results showed that the yield of the maize hybrids increased significantly at an average rate of 37.5% every 10 years. The evolution of NUE heterosis was mainly related to the increased kernel number per ear. The absolute NUE heterosis (AH_NUE) and the mid-parent NUE heterosis (MPH_NUE) of maize hybrids increased by 151.4% and 76.4% in the past four decades, or an average rate of 2.11 kg kg⁻¹ and 19.1% every 10 years. Based on the coefficient of determination, the contribution of the mid-parent nitrogen internal efficiency heterosis (MPH_NIE) to MPH_NUE (43–57%) was significantly higher than that of the mid-parent nitrogen recovery efficiency heterosis (MPH_NRE) (19–32%), indicating that the evolution of maize NUE heterosis was mainly derived from its NIE heterosis evolution. The increase of NIE heterosis in the past 40 years was closely related to the increased heterosis of kernel number per ear, the pre-silking N accumulation and the post-silking N remobilization. Therefore, the enhancement of maize NUE heterosis can be attributed to (i) heterosis improvement in post-silking N remobilization, which results mainly from greater heterosis in pre-silking N accumulation; (ii) heterosis improvement in carbon and nitrogen sink capacity, which exhibit as heterosis enhancement in grain yield and grain nitrogen concentration. To further improve yield and NUE, the pre-silking N and carbon accumulation and post-silking N remobilization should both continue to increase in maize breeding. Our results will provide new insights into NUE and help breeders select genotypes with both higher yields and higher NUE for the future.

Precipitation is the major cause of yield variation in rainfed agriculture production on the Loess Plateau. Overfertilization is economically and environmentally undesirable. Optimizing nitrogen management based on fallow season precipitation is crucial for enhancing crop water use efficiency and achieving high yields in dryland/rainfed farming systems, considering the economic and environmental drawbacks of overfertilization and the uncertainty of crop yield and N input returns under high rainfall variability. Therefore, this study establishes a reference range that characterizes different wheat cultivation year types based on 37 years of fallow season precipitation data. The reference range for describing years as normal (220.7–346.2 mm), dry (< 220.7 mm), or wet (> 346.2 mm) is based on a 37-year precipitation record. At the same time, an 8 year field experiment (A randomized block design) was conducted using 7 N rates(0, 90, 120, 150, 180, 210, 240 kg N ha^-1 to explore the prediction of PF on optimal N input for higher yield and water use efficiency (WUE). Optimum nitrogen (N) rates varied with the precipitation factor, being 150, 150–180, and 210 kg ha^− 1 during dry, normal, and wet years respectively. Maximizing yield and water use efficiency (WUE) through optimized N input was primarily attributed to an increase in spike number per hectare. A non-linear regression analysis revealed a positive correlation between yield and precipitation frequency (PF), with an increase in yield ranging from 1.6 to 15 kg ha-1 for every mm increment in PF. Furthermore, the study demonstrated that an increase of 1% in the ratio of PF to total precipitation resulted in a significant yield gain of 46 kg ha^-1.And as “drought at sowing” effects on yield were more adverse than “drought in growing season” effects in dryland systems, our results indicate that adjusting N fertilizer inputs based on summer rainfall variation could enhance wheat yield and WUE in the rainfed farming system. Thus, our results indicate that adjusting N fertilizer inputs based on seasonal variation in summer rainfall could enhance wheat yield and WUE in the rain-fed farming system.

This study evaluated the potential of Wonheug, a novel soybean cultivar, as an alternative soybean meal (SBM) source in broiler diets for improving growth performance, nutrient digestibility, carcass yield, and tibia characteristics. Wonheug soybeans were processed via hexane solvent extraction to produce SBM for experimental diets. Two SBM types, a commercial SBM and Wonheug-sourced SBM, were compared over a 42-day feeding trial. A total of 200 day-old Arbor Acre broilers (mean initial body weight, 43.90 ± 0.37 g) were randomly assigned to two groups, each with five replicates of 20 birds. Compared with commercial SBM, Wonheug-sourced SBM contained higher crude protein (P = 0.028), phosphorus (P = 0.004), and methionine (P = 0.002) contents. Broilers fed the Wonheug-sourced SBM-based diet exhibited greater body weight gain (P = 0.001), improved feed efficiency (P = 0.020), enhanced digestibility of crude protein (P = 0.044), calcium (P = 0.008), and phosphorus (P = 0.002), increased breast (P = 0.004) and leg meat (P = 0.027) yields, as well as better tibia characteristics, including weight (P = 0.020), length (P = 0.033), weight-to-length ratio (P = 0.019), and medullary canal diameter (P = 0.006). Therefore, the results obtained in the present study suggest that Wonheug-sourced SBM is a high-quality and functional feed ingredient which can enhance growth performance, nutrient digestibility, carcass yield, and tibia characteristics of broilers, thereby supporting more sustainable and efficient broiler production.