Rapid emergence and high-quality seedlings are an important basis for achieving high yields and high-quality grains in wheat production. It is not clear how long-term straw incorporation affects the emergence and quality of wheat seedlings in lime concretion black soil. Based on a 12-year long-term fixed-site experimental field, a three-year field experiment with wheat-maize rotation was conducted on the Huang-Huai-Hai Plain of China in 2020-2023 to assess the effect of straw incorporation on seedling emergence and seedling quality of wheat. The treatments comprised no-tillage wheat straw mulching and conventional tillage with maize straw return (T1), conventional tillage with maize straw return only (T2), and without straw incorporation (CK). The results showed that seedling emergence time (SET) and seedling emergence peak day (SEPD) in the T1 and T2 treatments were delayed compared with those of the CK. The SET was delayed (by 0.3-2.0 d), and the seedling emergence speed (SES) decreased (by 5.88%-25.01%), whereas the differences in emergence rate were not significant. The T1 and T2 treatments led to increases in leaf area, number of tillers per plant, and number of secondary roots at the six-leaf stage compared with those of the CK. Principal component analysis revealed that the first principal component that affected wheat seedling growth was dominated by the leaf area index and the net assimilation rate, whereas the leaf weight ratio mainly contributed to the second principal component. Straw incorporation delayed the wheat SET and the SEPD, and reduced the SES in the seedling emergence stage, but increased the leaf area, number of tillers per plant, and number of secondary roots in the seedling establishment stage, thereby promoting the development of strong seedlings. This study provides theoretical support for the efficient utilization of straw resources and the improvement of the quality of wheat seedlings on the Huang-Huai-Hai Plain.

With the intensification of climate change, spring low-temperature stress (SLTS) leads to floret degeneration and a decrease in grain number. This study investigated the physiological mechanisms underlying SLTS-induced floret degeneration using two wheat varieties with contrasting cold sensitivity. SLTS caused yellowing and shrinkage of floret primordia, increasing floret degeneration and fertile floret abortion, ultimately reducing grains per spike by 12.2%–26.1%. SLTS disrupted nutrient supply, impairing dry matter accumulation in young spikes. At 0–15 d after low-temperature stress (DALTS), SLTS caused a brief increase in the sugar content of young spikes (0–3 DALTS), followed by a rapid decrease (6–15 DALTS), while the total nitrogen content keeps decreasing. SLTS altered key enzyme activities, enhancing sucrose synthase and sucrose phosphate synthase but suppressing nitrate reductase and glutamine synthetase. Transcriptomic analysis revealed that SLTS perturbed starch and sucrose metabolism, carbon and nitrogen metabolism, and amino sugar pathways, altering soluble sugars, sucrose, fructose, and protein levels. SLTS disrupted carbon–nitrogen metabolic homeostasis, thereby reducing the number of fertile florets and ultimately leading to a decrease in grain number per spike. These findings enhance understanding of SLTS impacts on wheat floret development and provide insights for improving low-temperature tolerance and yield stability in wheat.

A large amount of straw has been an agricultural resource in recent years. Straw returning mode can also determine the soil fertility and wheat yield. Among them, grain filling is one of the important influencing factors on wheat yield. This study aims to reveal the effects of straw returning mode on the grain filling of winter wheat in sand ginger black soil. The 15 a long-term positioning experiment was carried out at the Crop Cultivation Scientific Observation Station in East China of the Ministry of Agriculture and Rural Affairs. Yannong19 was taken as the research object. Four modes of straw returning were set, namely, single-season wheat straw total crushing mulching and returning to field (T1), wheat straw total crushing and mulching and returning to field + corn straw total crushing and burying to field (T2), single-season corn straw total crushing and burying to field (T3) and wheat-corn straw no returning to field all year round (CK). Richards equation was used to simulate the grain filling of winter wheat. Different modes of straw returning were regulated on the filling characteristic parameters for the superior and inferior grains of winter wheat. The results showed as follows: Compared with non-returning straw, straw-returning treatment increased the grain volume, 1000-grain weight, and yield of superior and inferior winter wheat. The 1 000-grain weight and grain yield of superior grain under T1, T2, and T3 treatment significantly increased by 11.02%, 10.63%, 13.75%, and 16.28%, 14.29% and 13.94%, respectively, compared with the CK. The 1000-grain weight and grain yield of inferior grain significantly increased by 9.73%, 6.64%, 7.57% and 19.24%, 23.25%, 11.50%, respectively. Richards equation was performed better to simulate the grain filling of winter wheat under straw returning. The coefficient of determination (R²) of the fitted equation was above 0.997. In the superior grain of winter wheat, straw returning to the field also prolonged the filling time of the superior grain of wheat, thus shortening the duration of the gradual filling period. The filling rate increased to extend the duration of the slow filling period for the increase in the 1000-grain weight of superior grain. The filling duration of superior grain under T1 and T3 treatments was 2.137d and 4.443d longer than that of CK, respectively. The maximum filling rate of superior grain under T1 and T2 treatments significantly increased by 7.81% and 12.26%, respectively, compared with the CK. For an inferior grain of winter wheat, the filling time of inferior grain under T1 treatment was 1.477 d longer than that of CK, and the maximum filling rates of inferior grain in T1, T2, and T3 significantly increased by 16.46%, 22.69%, and 17.13%, respectively, compared with the CK. Therefore, the total straw returning increased the grain storage and grain filling rate of winter wheat in the area of sandy ginger black soil. Finally, there was an increase in the grain weight. The finding can provide theoretical guidance and technical support for the efficient utilization of straw resources in sand-ginger black soil areas.

Increasing the grain yield (GY) and water use efficiency (WUE) of winter wheat in the Huaibei Plain (HP), China are essential. However, the effects of micro-sprinkler irrigation and topsoil compaction after wheat seed sowing on the GY and WUE are unclear. Therefore, a two-year field experiment was conducted during the 2021–2023 winter wheat growing seasons with a total six treatments: rain-fed (RF), conventional irrigation (CI) and micro-sprinkler irrigation (MI), as well as topsoil compaction after seed sowing under these three irrigation methods (RFC, CIC, and MIC). The results in the two years indicated that MI significantly increased GY compared to CI and RF, by averages of 17.9 and 42.1%, respectively. The increase in GY of MI was due to its significant increases in the number of spikes, kernels per spike, and grain weight. The chlorophyll concentration in flag leaves of MI after the anthesis stage maintained higher levels than with CI and RF, and was the lowest in RF. This was due to the dramatically enhanced catalase and peroxidase activities and lower malondialdehyde content under MI. Compared with RF and CI, MI significantly promoted dry matter remobilization and production after anthesis, as well as its contribution to GY. In addition, MI significantly boosted root growth, and root activity during the grain-filling stage was remarkably enhanced compared to CI and RF. In 2021–2022, there was no significant difference in WUE between MI and RF, but the WUE of RF was significantly lower than that of MI in 2022–2023. However, the WUE in MI was significantly improved compared to CI, and it increased by averages of 15.1 and 17.6% for the two years. Topsoil compaction significantly increased GY and WUE under rain-fed conditions due to improved spike numbers and dry matter production. Overall, topsoil compaction is advisable for enhancing GY and WUE in rain-fed conditions, whereas micro-sprinkler irrigation can be adopted to simultaneously achieve high GY and WUE in the HP.

Late spring cold (LSC) occurred in the reproductive period of wheat impairs spike and floret differentiation during the reproductive period, when young spikelets are very cold-sensitive. However, under LSC, the responses of wheat spikelets at various positions, leaves, and stems and the interactions between them at physiological levels remain unclear. In the present study, two-year treatments at terminal spikelet stage under two temperatures (2 °C, −2 °C) and durations (1, 2, and 3 days) were imposed in an artificial climate chamber to compare the effects of LSC on grain number and yield in the wheat cultivars Yannong 19 (YN19, cold-tolerant) and Xinmai 26 (XM26, cold-sensitive). The night temperature regimes were designed to reproduce natural temperature variation. LSC delayed plant growth and inhibited spike and floret differentiation, leading to high yield losses in both cultivars. LSC reduced dry matter accumulation (DMA, g) in spikes, stems, and leaves, reducing the DMA ratios of the spike to leaf and spike to stem. Plant cell wall invertase (CWINV) activity increased in upper and basal spikelets in YN19, whereas CWINV increased in middle spikelets in XM26. Under LSC, soluble sugar and glucose were transported and distributed mainly in upper and basal spikelets for glume and rachis development, so that spike development was relatively complete in YN19, whereas the upper and basal spikelets were severely damaged and most of the glumes in middle spikelets were relatively completely developed in XM26, resulting in pollen abortion mainly in upper and basal spikelets. The development of glumes and rachides was influenced and grain number per spike was decreased after LSC, with kernels present mainly in middle spikelets. Overall, reduced total DMA and dry matter partitioning to spikes under LSC results in poor spikelet development, leading to high losses of grain yield.