Nitrogen (N) application rates and planting density are key factors affecting grain yield and quality. In this experiment, four varieties, Huijing 753 (HJ 753), Huijing 855 (HJ 855), Huijing 866 (HJ 866), and Dangjing 8 (DJ 8), were used to investigate their effects on the yield and quality of japonica rice in Anhui, which has a lower soil N supply capacity. The current study set four levels of N application N1, N2, N3, and N4 (120, 180, 240, and 300) kg ha⁻¹ and three planting densities D1, D2, and D3 (high-density: 45 × 10⁴; medium-density: 37.5 × 10⁴; low-density: 32.2 × 10⁴) hills ha⁻¹ for a total of 12 treatments. The effects of N application and planting density on rice yield, composition, processing quality, appearance quality, and cooking quality were analyzed. The results showed that with the increase in N application rates and planting density, the effective panicle number per plant and grain number per panicle of each rice variety increased, while HJ 753, HJ 855, and HJ 866 reached the highest yield under the N3D1 treatment and then gradually declined, and DJ 8 had the highest yield in the N4D1 treatment. In addition, the processing quality of various varieties can be improved by increasing the N application rate and planting density, but the appearance quality will deteriorate, the amylose content will also decrease, and gel consistency will also be lower. Therefore, under medium-planting density conditions, N at a rate of 240 kg ha⁻¹ was the best for HJ 753, HJ 855, and HJ 866, and using 300 kg ha⁻¹ for DJ 8 resulted in high grain yields and superior rice grain quality. In the next step, physiological, biochemical, and genotypic analyses of these three japonica rice varieties were carried out to provide a scientific basis and technical support for accelerating the breeding of high-yield japonica rice varieties.

Background: INDETERMINATE DOMAIN proteins (IDDs) are a plant-specific transcription factor family, and members of this family play crucial roles in regulating growth and development as well as environmental adaptation. However, a comprehensive analysis of the IDD family in soybean [Glycine max (L.) Merrill] is limited. Methods and Results: A total of 27 GmIDD genes were identified in the soybean genome, unevenly distributed across 14 chromosomes, and their encoded proteins all harbor a conserved INDETERMINATE (ID) domain with two Cys2His2 (C2H2) and two Cys2HisCys (C2HC) zinc finger motifs. Phylogenetic analysis classified these GmIDD genes into three subgroups. Soybean GmIDD genes exhibit high homology with their Arabidopsis thaliana IDD counterparts. Cis-acting element analysis indicated that the promoters of GmIDD genes are enriched in light-responsive elements (such as Box4), hormone-responsive elements (such as ABRE and AuxRR-core), and abiotic stress-responsive elements (such as MBS and LTR). The qRT-PCR results showed that GmIDD3/5/14/22/26 were upregulated under salt stress, while GmIDD8/9/10/12/16/17/19/20/23/24/25/27 were obviously downregulated during treatment. Under drought stress, the expression levels of GmIDD4/6/7/10/14/16/19/22/24/25/26/27 were upregulated during the treatment. The expression levels of GmIDD1/2/3/4/12/14/15/16/17/18/22/23/25/26 were induced by short-day conditions, whereas GmIDD9/13/19/21 were induced by long-day conditions in soybean leaves. Conclusions: This study provides a theoretical basis for further understanding the functions of the soybean IDD gene family in abiotic stress tolerance and photoperiod adaptability.