Plant height (PH) is one of the most important components of the plant ideotype, and it affects plant biomass, yield, lodging resistance, and the ability to use mechanized harvesting.  Since many complex pathways controlling plant growth and development remain poorly understood, we are still unable to obtain the most ideal plants solely through breeding efforts.  PH can be influenced by genotype, plant hormonal regulation, environmental conditions, and interactions with other plants.  Here, we comprehensively review the factors influencing PH, including the regulation of PH-related developmental processes, the genetics and QTLs contributing to PH, and the hormone-regulated molecular mechanisms for PH.  Additionally, the symbiotic influence of grafting on PH is discussed, focusing on the molecular regulation of gene expression and genetics.  Finally, we propose strategies for applying recent findings to breeding for better PH, highlight some knowledge gaps, and suggest potential directions for future studies.

Tillage practices during the fallow period benefit water storage and yield in dryland wheat crops.  However, there is currently no clarity on the responses of soil organic carbon (SOC), total nitrogen (TN), and available nutrients to tillage practices within the growing season.  This study evaluated the effects of three tillage practices (NT, no tillage; SS, subsoil tillage; DT, deep tillage) over five years on soil physicochemical properties.  Soil samples at harvest stage from the fifth year were analyzed to determine the soil aggregate and aggregate-associated C and N fractions.  The results indicated that SS and DT improved grain yield, straw biomass and straw carbon return of wheat compared with NT.  In contrast to DT and NT, SS favored SOC and TN concentrations and stocks by increasing the soil organic carbon sequestration rate (SOC_SR) and soil nitrogen sequestration rate (TN_SR) in the 0–40 cm layer.  Higher SOC levels under SS and NT were associated with greater aggregate-associated C fractions, while TN was positively associated with soluble organic nitrogen (SON).  Compared with DT, the NT and SS treatments improved soil available nutrients in the 0–20 cm layer.  These findings suggest that SS is an excellent practice for increasing soil carbon, nitrogen and nutrient availability in dryland wheat fields in North China.

Two microRNA (miRNA) quantification methods, namely, poly(A) reverse transcription (RT)-quantitative real-time polymerase chain reaction (qPCR) and stem-loop RT-qPCR, have been developed for quantifying miRNA expression. In the present study, five miRNAs, including miR166, miR167, miR168, miR159, and miR396, with different sequence frequencies, were selected as targets to compare their expression profiles in five wheat tissues by applying the two methods and deep sequencing. The study aimed to determine a simple, reliable and high-throughput method for detecting miRNA expressions in wheat tissues. Results showed that the miRNA expression profiles determined by poly(A) RT-qPCR were more consistent with those obtained by deep sequencing. Further analysis indicated that the correlation coefficients of the data obtained by poly(A) RT-qPCR and deep sequencing (0.739, P 0.01) were higher than those obtained by stem-loop RT-qPCR and deep sequencing (0.535, P 0.01). The protocol used for poly(A) RT-qPCR is simpler than that for stem-loop RT-qPCR. Thus, poly(A) RT-qPCR was a more suitable high-throughput assay for detecting miRNA expression profiles. To the best of our knowledge, this study was the first to compare these two miRNA quantification methods. We also provided useful information for quantifying miRNA in wheat or other plant species.

Nitrogen use efficiency in rice is lower than in upland crops, likely due to differences in soil nitrogen dynamics and crop nitrogen preferences. However, the specific nitrogen dynamics in paddy and upland systems and their impact on crop nitrogen uptake remain poorly understood. The N dynamics and impact on crop N uptake determine the downstream environmental pollution from nitrogen fertilizer. To address this poor understanding, we analyzed 2,044 observations of gross nitrogen transformation rates in soils from 136 studies to examine nitrogen dynamics in both systems and their effects on nitrogen uptake in rice and upland crops. Our findings revealed that nitrogen mineralization and autotrophic nitrification rates are lower in paddies than in upland soil, while dissimilatory nitrate reduction to ammonium is higher in paddies, these differences being driven by flooding and lower total nitrogen content in paddies. Rice exhibited higher ammonium uptake, while upland crops had over twice the nitrate uptake. Autotrophic nitrification stimulated by pH reduced rice nitrogen uptake, while heterotrophic nitrification enhanced nitrogen uptake of upland crops. Autotrophic nitrification played a key role in regulating the ammonium-to-nitrate ratio in soils, which further affected the balance of plant nitrogen uptake. These results highlight the need to align soil nitrogen dynamics with crop nitrogen preferences to maximize plant maximize productivity and reduce reactive nitrogen pollution.