Hybrid selection and water management practices are crucial for sustaining corn productivity. The adoption of short-season hybrid (SS) represents the viable strategy to facilitate corn production in the North China Plain. However, there is limited information available regarding grain yield (GY) and water consumption characteristics for SS in this region. The three-year experiment was carried out under the rain-shelters with SS and fullseason hybrid (FS). Corn plants were grown under three irrigation amounts (target relative soil moisture content was at 60% (WL), 75 % (WM), and 90% (WH) of field capacity). The results showed the GY for FS was 6.7 % higher than that for SS, SS obtained comparable or even higher water use efficiency (WUE) than FS. Soil evaporation (E) and crop evapotranspiration (ET) for SS were decreased by 7.2 % and 9.5%, compared with those for FS. The higher irrigation level resulted on the higher the intensity of daily water consumption during three growing seasons. The relationship between GY and ET was fitted to the quadratic function. A logarithmic relationship was observed between the ratio of soil E to ET and the leaf area index. The soil E and ET of summer corn demonstrated an increase with the augmentation of applied irrigation water. WM had statistically similar (p > 0.05) yield and N fertilizer partial factor productivity (NPFP) compared to WH. The TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) method showed the FSWM treatment ranked first, followed by SSWM treatment. WM was the appropriate irrigation level for both hybrids to maintain yields, improve efficiency and optimize water consumption characteristics. This study provided scientific insights into corn yield and water consumption characteristics in relation to hybrid maturity and water management practices.

Manure substitution shows promise for nitrogen (N) management, food security, energy balance and environmental costs reduction. However, there is limited research on this practice in the Huanghuaihai Plain. This study aimed to investigate the energy use efficiency, economic benefits, carbon and nitrogen footprint under two types of N fertilizer (U, urea and M, organic manure), two application rates of N (180 kg N ha- 1 , U1 for 100 % urea and M1 for 100 % organic manure; 90 kg N ha- 1 , U2 for 50 % urea and M2 for 50 % organic manure) and no fertilizer application treatment (CK) for winter wheat from 2017 to 2019. Results showed that grain yield and agricultural input cost under N application rate of 90 kg N ha- 1 was 15.5 % and 7.8 % lower than that of 180 kg N ha- 1 , respectively, leading to a significant decrease in economic benefit. Under the same N rate, M1 obtained higher grain yield than U1, grain yield of M2 did no differ in that of U2. Total energy inputs and agricultural input costs of M were 9.5 % and 3.6 % lower than U, resulting in higher energy use efficiency and economic benefit. The reduced agricultural input for M was primarily due to a decrease in the application of inorganic fertilizer. Compared with other treatments, U2+M2 obtained higher grain yield, energy use efficiency, and economic benefit. The carbon and nitrogen footprint on unit grain yield of U1 was increased by 13.7 %-24.1 % and 3.9 %19.6 %, which was attributed to the increase in direct N2O emissions, indirect carbon emission and losses of reactive N from agricultural inputs. Overall, U2+M2 sustained high productivity and reduced the environmental impact. Substituting inorganic fertilizer with organic manure was a promising strategy to improve agricultural production with less agricultural inputs and environmental footprints in the Huanghuaihai Plain.

Water requirements of early-maturing (EM) maize hybrids might be lower than those of late-maturing (LM) maize hybrids. This study aimed to analyze the effects of different irrigation management on grain yield (GY), water uptake patterns, evaporation (E), and transpiration (T) of two maize hybrids differing in maturity via stable isotope method. The field experiment with 36 lysimeters (4-m wide x 4-m long) under rain-shelters was conducted with an EM (DH518) and a mid-maturing and LM (DH605) hybrid with three replicates from 2021 to 2022. Maize plants were grown under three irrigation amounts (W1, W2, and W3 were irrigated to maintain soil moisture at 45%, 60%, and 75% of field capacity, respectively) by flood irrigation (FI) and drip irrigation (DI) under rain-out shelters. Results showed that GY and evapotranspiration (ET) of EM were 8% and 12% lower, while the crop water productivity (CWP) was 6% higher than that of LM. Water uptake of both hybrids occurred mainly within 0- to 60-cm soil layer during the vegetative stage. Water uptake of both hybrids occurred mainly within 0- to 60-cm soil layer during the vegetative stage. Summer maize under FI absorbed more water from the deep soil layer than DI in the late growth stage. Compared with LM, the water absorption depth of EM became shallower in the late growth stage. Water uptake of maize was mainly from the deeper soil under water stress conditions. E of total ET accounts for 43% under DI and 57% under FI; GY and CWP were 22% and 51% higher than those of FI. Together with choosing EM hybrids, optimization of water management with DIW3 could achieve higher GY and CWP. The optimization of irrigation method and hybrids could provide a reference for local farmers to improve GY and CWP. An IsoSource model effectively determined seasonal change in water-uptake patterns for different maize genotypes.The stable isotope technique could be an effective method to partition evaporation and transpiration.The main water absorption depth of maize changed greatly over the growth period and was affected by irrigation.The early-maturing hybrid obtained higher crop water productivity and absorbed water from the shallower soil layer.Evaporation of total evapotranspiration accounts for 43% under drip irrigation and 57% under flood irrigation.

Corn-peanut intercropping is an important element of China’s agricultural planting model as it confers ecological benefits and increases yield. The aim of this study was to explore the productivity differences between intercropping and monoculture by using the 13C isotope tracer labelling method. Corn hybrid Denghai 618 (DH618) and peanut variety Huayu 22 (HY22) were used as test materials under three planting methods, single corn, SM; single peanut, SP; and corn-peanut intercropping, IM and IP, respectively, during two growing seasons. The results showed that IM increased yield by 59.7% and 62.3% compared with SM, respectively. IP reduced yield by 31.3% and 32.3% compared with SP, respectively. IM significantly increased the photosynthetic rate, leaf area, 13C assimilation distribution, and dry matter accumulation of summer corn, which led to an increase in the kernel number and grain yield. The decrease in intercropped peanut yield was mainly caused by a decrease in the full-pod rate and number of pods per plant. The decrease in peanut yield did not affect the production of intercropping benefit due to the larger intercropping advantage and land equivalence ratio. Corn-peanut intercropping yielded greater economic benefits than monoculture. These results showed the utility of the peanut-corn intercropping model.

Background: Soil salt stress is a problem in the world, which turns into one of the main limiting factors hindering maize production. Salinity significantly affects root physiological processes in maize plants. There are few studies, however, that analyses the response of maize to salt stress in terms of the development of root anatomy and respiration. Results: We found that the leaf relative water content, photosynthetic characteristics, and catalase activity exhibited a significantly decrease of salt stress treatments. However, salt stress treatments caused the superoxide dismutase activity, peroxidase activity, malondialdehyde content, Na+ uptake and translocation rate to be higher than that of control treatments. The detrimental effect of salt stress on YY7 variety was more pronounced than that of JNY658. Under salt stress, the number of root cortical aerenchyma in salt-tolerant JNY658 plants was significantly higher than that of control, as well as a larger cortical cell size and a lower root cortical cell file number, all of which help to maintain higher biomass. The total respiration rate of two varieties exposed to salt stress was lower than that of control treatment, while the alternate oxidative respiration rate was higher, and the root response of JNY658 plants was significant. Under salt stress, the roots net Na+ and K+ efflux rates of two varieties were higher than those of the control treatment, where the strength of net Na+ efflux rate from the roots of JNY658 plants and the net K+ efflux rate from roots of YY7 plants was remarkable. The increase in efflux rates reduced the Na+ toxicity of the root and helped to maintain its ion balance. Conclusion: These results demonstrated that salt-tolerant maize varieties incur a relatively low metabolic cost required to establish a higher root cortical aerenchyma, larger cortical cell size and lower root cortical cell file number, significantly reduced the total respiration rate, and that it also increased the alternate oxidative respiration rate, thereby counteracting the detrimental effect of oxidative damage on root respiration of root growth. In addition, Na+ uptake on the root surface decreased, the translocation of Na+ to the rest of the plant was constrained and the level of Na+ accumulation in leaves significantly reduced under salt stress, thus preempting salt-stress induced impediments to the formation of shoot biomass.

Tillage method does exert a certain regulatory effect on yield of rainfed crops.A field experiment was established on the Loess Plateau and was for 8 years during 2009-2017.Three types of fallow tillage (no-tillage, deep plough and subsoiling) were used, and divided the yield with cluster analysis, studied the relationship of the main yield components and precipitation, soil water storage and water use.The results showed that the yield of wheat was influenced by the adjustment of the distribution of yield components in different precipitation years, and the number of plural was the main factor to obtain higher yield, which was influenced by the precipitation during the fallow-period and the sowing-anthesis period, the reasonable distribution of grain number per spike and 1000-grain weight is the factor of high yield, which is mainly affected by precipitation and soil water consumption at the later growth stage.In addition, cultivation during fallow-period can achieve higher yield, but under the influence of precipitation type, DP during growth-dry year type was more favorable to the increase of field evapotranspiration, the growth-wet type of SS was more beneficial to the improvement of water use efficiency.

Aims To realize the so-called “Second Green Revolution”, it is imperative to study the roots of crop plants, and identify those traits that improve the efficiency of nitrogen (N) acquisition. We aimed to evaluate how the N acquisition efficiency of six hybrid maize lines commonly grown in northern China depends on their root anatomy. Methods Maize hybrids classified as having high nitrogen uptake efficiency (HNUE) and low nitrogen uptake efficiency (LNUE) were grown under high-N and low-N conditions in the greenhouse and the field. Results Under N stress in the field and the greenhouse, HNUE increased shoot dry weight, root length density, N content and nitrogen use efficiency compared to LNUE. Low N availability increased the percentage of root cortical aerenchyma and the size of cortical cells. Root anatomy, with greater formation of root cortical aerenchyma and larger cortical cell size, was associated with increased specific nitrogen absorption efficiency (SNAE) and shoot biomass under N stress. Under low N availability, the percentage of aerenchyma and their total area had significant positive correlations with the shoot dry weight, total N uptake, SNAE. Conclusions The results suggest that plants in limited N availability form more root cortical aerenchyma and have larger cortical cells, which is of benefit to root growth, soil exploration, N acquisition, and shoot biomass. These observations support the hypothesis that root anatomical phenotypes that affect the metabolic and construction costs of producing root length merit consideration as selection criteria for breeding to improve N acquisition in hybrid maize.

The growth and development of maize is affected in a crucial way by the salinity of the soil it grows in. Therefore, if we want to improve the salt tolerance of maize, it is of paramount importance to understand how it responds to salt stress. To explore how maize adapts to a saline environment, we chose one salt-tolerant maize variety, Jingnongyu 658 (JNY658), and one salt-sensitive variety, Yunyu7 (YY7), and treated the seedlings of both varieties with a 100 mM NaCl solution. After harvesting them, we analysed the adaptive responses to salt stress with respect to various characteristics of the root architecture and water and nutrient acquisition. We found that when subjected to salt stress, both varieties exhibited a reduction in biomass, root activity, N-15 and (H2O)-O-18 uptake amount, lateral root branching density, lateral root length, total root length, root surface area and root volume, where the YY7 suffered a greater reduction than the JNY658. Salt stress also induced a decreased absorption of K+, passively promoted the absorption of Na+ and gave rise to an increased Na+/K+ ratio in the roots of both varieties. It should be noted that JNY658 exposed to salt stress developed a lower Na+/K+ ratio than YY7. Compared with the control group, the expression of ZmSOS1, ZmSOS2 and ZmNHX genes in the roots of JNY658 subjected to salt stress was significantly upregulated, which enabled them to maintain a lower Na+ content. In both varieties, the salicylic acid (SA) and gibberellin(19) acid (GA(19)) content increased significantly, but the auxin (IAA), jasmonic acid (JA) and trans-zeatin (TZ) content was reduced. In addition, JNY658 in salt stress significantly increased their abscisic acid (ABA) content, due to the increased expression of its key biosynthesis genes, NCED. Compared with JNY658, the reductions in IAA, JA and TZ content in YY7 were greater, while the increases in ABA and SA content were smaller. The varieties in the ABA, JA, SA and IAA of roots subjected to salt stress significantly or extremely significantly correlated with the lateral root branching density, lateral root length, root surface area, Na+ content, K+ content and Na+/K+ ratio. We conclude that the salt-tolerant maize variety mitigated the toxic effect of salinity on maize root growth and development by regulating the hormone content and enhancing its expression of stress-responsive genes while maintaining ion homeostasis and promoting water and nutrient acquisition, which ultimately resulted in a less pronounced decrease in plant biomass.

Stable yield of staple grains must be ensured to satisfy food demands for daily dietary energy requirements against the backdrop of global climate change. Summer maize, a staple crop, suffers severe yield losses due to extreme rainfall events, threatening food security. A randomized block experiment with four treatments: control, no water stress (CK); waterlogging for 6 days at the third leaf, sixth leaf stage, and 10th day after tasseling, was conducted to investigate the mechanism of waterlogging-induced yield losses of summer maize. Waterlogging delayed plant growth and impaired tassel and ear differentiation, leading to high grain yield losses of Denghai 605 (DH605). Waterlogging at third leaf (V3) stage reduced the photosynthesis of DH605, reducing total dry matter weight. Waterlogging at V3 stage reduced sucrose-cleaving enzymes activities in spike nodes and ears, reducing the carbon partitioned to ears (–53.1%), shanks (–46.5%), and ear nodes (–71.5%) but increasing the carbon partitioned to ear leaves (9.6%) and tassels (43.9%) in comparison with CK. The reductions in total carbon assimilate together with the reduced carbon partitioning to ears resulted in poor development of spikes (with respectively 15.2% and 20.6% reductions in total florets and fertilized florets) and lengthened the anthesis–silking interval by around 1 day, leading to high yield losses.

Planting maize at high densities leads to early leaf senescence, and the resulting reduction in the number of lower leaves affects the plant's root function and lowers its grain yield. However, the nature of the process by which lower leaf senescence affects biomass accumulation and grain yield formation in maize is not clear. This study aimed to shed light on how these factors are related by investigating the effects of the plant growth regulator 6-benzyladenine (6-BA) on the senescence of lower leaves of maize plants. In two maize cultivars planted at densities of 67,500 (low density, LD) and 90,000 (high density, HD) plants ha−1, plants treated with 6-BA maintained a high green leaf area index (LAI) longer than control (CK) plants, enabling them to maintain a higher photosynthetic rate for a longer period of time and produce more biomass before reaching physiological maturity. Spraying the lower leaves of maize plants with a 6-BA solution increased the distribution of 13C-photosynthates to their roots, lower leaves and bracts, a result that can be ascribed to a decreased retention of 13C-photosynthates in the stem and grain. In both seasons of the experiment, maize plants treated with 6-BA accumulated more N in grain and maintained a higher N content in roots and leaves, especially in lower leaves, than CK. Increased C assimilation in the lower leaves may explain why N uptake in plants subjected to the 6-BA treatment exceeded that in CK plants and why both photosynthesis rate and dry matter accumulation were maintained throughout grain filling. Our results suggest that a suitable distribution of C and N in leaves post-silking may maintain plant root function, increase N use efficiency, maximize the duration of high LAI, and increase grain yield.

Miscanthus , a member of the Saccharinae subtribe that includes sorghum and sugarcane, has been widely studied as a feedstock for cellulosic biofuel production. Here, we report the sequencing and assembly of the Miscanthus floridulus genome by the integration of PacBio sequencing and Hi-C mapping, resulting in a chromosome-scale, high-quality reference genome of the genus Miscanthus . Comparisons among Saccharinae genomes suggest that Sorghum split first from the common ancestor of Saccharum and Miscanthus , which subsequently diverged from each other, with two successive whole-genome duplication events occurring independently in the Saccharum genus and one whole-genome duplication occurring in the Miscanthus genus. Fusion of two chromosomes occurred during rediploidization in M. floridulus and no significant subgenome dominance was observed. A survey of cellulose synthases (CesA) in M. floridulus revealed quite high expression of most CesA genes in growing stems, which is in agreement with the high cellulose content of this species. Resequencing and comparisons of 75 Miscanthus accessions suggest that M. lutarioriparius is genetically close to M. sacchariflorus and that M. floridulus is more distantly related to other species and is more genetically diverse. This study provides a valuable genomic resource for molecular breeding and improvement of Miscanthus and Saccharinae crops.

Exploring the optimal method of water and fertilizer application and N application rate for summer maize is important for achieving the high water and N efficiency in the North China Plain. We tested that the hypothesis that optimizing water and nitrogen application system could improve nitrogen (N) use efficiency and water productivity, and ensure sustainable yield of summer maize. The results showed that: the 216 kg N ha-1 of drip irrigation (DI) and micro-sprinkling irrigation (SI) could obtain the high grain yield compared with 270 kg N ha-1 of flooding irrigation (FI), which was achieved by maintaining a high 1000-grain weight and kernel number. However, the grain yield of 162 kg N ha-1 would be decreased significantly. Irrigation methods and N application rates had significant effects on the ammonia volatilization rate and ammonia volatilization accumulation of soil, N harvest index (NHI), N partial productivity and water productivity. Compared with FI, DI and SI could reduce the ammonia volatilization rate through applying little fertilizer-N by times, and reduce the ammonia volatilization accumulation of 19.5%-54.9%. In addition, under the same irrigation method, the NHI reached the maximum when the N application rate was 216 kg ha−1. Considering comprehensively, under the condition of this experiment, 216 kg N ha−1 is the best N application rate under DI or SI for maize.

Hybrids and planting density are the main factors affecting maize lodging resistance. Here, we aimed to elucidate the mechanism of the regulation of maize lodging resistance by comparing two hybrids at various planting densities from the perspective of lignin metabolism. Our results showed that compared to lodging-susceptible hybrid Xundan 20 (XD20), lodging-resistant hybrid Denghai 605 (DH605) showed a lower center of gravity and culm morphological characteristics that contributed to the higher lodging resistance of this hybrid. Lignin content, activities of key lignin synthesis-related enzymes and G-, S-and H-type monomer contents were significantly higher in hybrid DH605 than in hybrid XD20. Stalk mechanical strength, lignin accumulation and enzyme activity decreased significantly with increasing planting density in the two hybrids. While G-type monomers first decreased with increasing planting density but then remained stable, S-type monomers showed a decreasing trend, and H-type monomers showed an increasing trend. Correlation analysis showed that lodging rate was significantly correlated with plant traits and lignin metabolism. Therefore, maize hybrids characterized by high lignin accumulation, high lignin synthesis-related activities, high S-type monomer content, low center of gravity, high stem puncture strength, high cortical thickness, and small vascular bundle area are more resistant to lodging. High planting densities reduce stalk lignin accumulation, relevant enzyme activities and mechanical strength, thereby, ultimately increasing the lodging rate significantly.

Summer maize is frequently subjected to waterlogging damage because of increased and variable rainfall during the growing season. The application of 6-benzyladenine (6-BA) can effectively mitigate the waterlogging effects on plant growth and increase the grain yield of waterlogged summer maize. However, the mechanisms underlying this process and the involvement of 6-BA in relevant signal transduction pathways remain unclear. In this study, we explored the effects of 6-BA on waterlogged summer maize using a phosphoproteomic technique to better understand the mechanism by which summer maize growth improves following waterlogging. Application of 6-BA inhibited the waterlogging-induced increase in abscisic acid (ABA) content and increased the phosphorylation levels of proteins involved in ABA signaling; accordingly, stomatal responsiveness to exogenous ABA increased. In addition, the application of 6-BA had a long-term effect on signal transduction pathways and contributed to rapid responses to subsequent stresses. Plants primed with 6-BA accumulated more ethylene and jasmonic acid in response to subsequent waterlogging; accordingly, leaf SPAD, antioxidase activity, and root traits improved by 6-BA priming. These results suggest that the effects of 6-BA on hormone signal transduction pathways are anamnestic, which enables plants to show faster or stronger defense responses to stress.

Summer maize suffers severe yield losses due to waterlogging, threatening food security. Application of 6-benzyladenine (6-BA) can modify protein phosphorylation status, and increase plant tolerance to waterlogging. However, little is known regarding the functional roles of 6-BA-mediated phosphorylation events in regulating plant stress tolerance. Therefore, we conducted an experiment involving three treatments (control (CK), waterlogging at the third leaf stage for 6 days (V3-6), and application of 100 mg L-1 6-BA after waterlogging (V3-6-B)) to probe the impact of 6-BA on leaf phosphoproteome of waterlogged summer maize. Our results demonstrated that waterlogging affected the reversible phosphorylation of proteins that participated in chloroplast movement and differentiation as well as photoreaction and carbon fixation processes. However, application of 6-BA significantly mitigated the waterlogging effects on the phosphorylation level of these proteins. Accordingly, the chloroplast ultrastructure and photosynthetic performances of waterlogged summer maize were improved. These results indicated that application of 6-BA mediated extensive phosphorylation events to improve the absorption and dissipation of light energy, the assimilation and metabolism of carbon, and the ultrastructure of chloroplast, thus increasing the photosynthesis rate of waterlogged summer maize. consequently, the plant growth and grain yield of waterlogged summer maize were improved by application of 6-BA.

以郑单958为材料,通过不同种植密度,利用激光衍射粒度分析仪、扫描电镜及透射电镜,分析不同种植密度夏玉米胚乳籽粒淀粉粒粒度分布特征.结果表明,不同种植密度玉米籽粒淀粉粒的粒径下限一致(0.38 μm),上限D1＞D2＞D3;体积、表面积及数目均值:D2＞D3＞D1.从淀粉粒的扫描图可以看出不同处理淀粉粒形态及胚乳细胞内其他内含物含量均有差异.从淀粉粒的透射图可以看出,各处理间淀粉粒的发育、外形、排列以及其他质体的数量都存在较大差异;密度可以调节玉米胚乳淀粉粒的分布及形态.

Maize-peanut intercropping is an important element of China’s agricultural planting model, as it confers ecological benefits, promotes species diversity, and increases economic efficiency and yield. The aim of this study was to explore the yield differences between intercropping and monoculture, and to determine the mechanism underlying the high yield efficiency of the intercropping system using the 13 C isotope tracer labelling method. The early maturing corn hybrid Denghai 618 and the early maturing and high-yielding peanut variety Huayu 22 were used as test materials. Three kinds of planting methods were employed, i.e. the sole maize (SM), the sole peanut (SP) and maize–peanut intercropping (intercropped maize, IM; intercropped peanut, IP), for two consecutive years. IM increased yield by 59.7% and 62.3% comparing with SM in 2015 and 2016, respectively. IP reduced yield by 31.3% and 32.3% comparing with SP in 2015 and 2016, respectively. IM significantly increased the photosynthetic rate, leaf area, 13 C assimilation distribution, and dry matter accumulation of summer maize, which led to an increase in kernel number, resulting in an increased yield. The decrease in intercropped peanut yield was mainly caused by a decrease in the percent of plump pod and number of pods per plant. The decrease in peanut yield did not affect the production of intercropping, because of the large intercropping advantage and land equivalence ratio. Maize-peanut intercropping provided greater economic benefits than monoculture. These results showed the utility of the peanut-maize intercropping model.

[目的]探究密植条件下玉米品种混播对夏玉米籽粒灌浆性能及产量形成的影响.[方法]以郑单958(ZD958)和登海605(DH605)为试验材料,设置3个种植密度(D1,67500株/hm2;D2,82500株/hm2;D3,97500株/hm2)和2个不同混播方式(M:等种子量混合后随机播种;Ⅰ:1行郑单958和1行登海605混播),以相同密度下单播郑单958(SZD958)和登海605(SDH605)为对照,研究密植夏玉米品种混播对花后干物质积累与转运、籽粒灌浆特性和产量形成的影响.[结果]随种植密度增加,不同播种方式处理的花后干物质积累量显著增加,成熟期单株干物质积累量和籽粒灌浆参数降低;虽然千粒重降低但群体产量显著增加.在D1密度下,混播处理较单播无显著增产优势;D2和D3密度下,2个品种混播后夏玉米产量显著增加.D2密度下M和Ⅰ处理2年平均产量较SZD958分别增加8.70％和8.09％,较SDH605分别增加6.92％和6.32％;D3密度下M和Ⅰ处理2年平均产量较SZD958分别增加7.24％和7.55％,较SDH605分别增加4.98％和5.28％.D2和D3密度下,2个品种混播后增加了籽粒最大灌浆速率(Gmax)、灌浆速率最大时的生长量(Wmax)和粒重,且百粒重与灌浆速率达到最大时需要的天数(Tmax)、Wmax、Gmax、籽粒灌浆活跃期(P)呈极显著正相关.D2密度下M和Ⅰ处理2年平均Wmax较SZD958分别显著增加11.61％和11.12％,较SDH605分别增加5.86％和5.38％;D3密度下M和Ⅰ处理2年平均Wmax较SZD958显著增加10.32％和9.75％,较SDH605显著增加5.63％和5.08％.混播后成熟期单株干物质积累量、花后干物质积累量、转运量、干物质转运率较单播增加.D2密度下M和Ⅰ处理2年平均花后干物质积累量较SZD958分别显著增加4.43％和7.56％,较SDH605分别显著增加5.25％和8.36％;D3密度下M和Ⅰ处理2年平均花后干物质积累量较SZD958分别显著增加3.85％和4.68％,较SDH605分别显著增加4.52％和5.36％.[结论]低密度下混播无增产效应,在82500株/hm2和97500株/hm2密度下,混播显著增加了花后干物质积累与转运,提高了夏玉米籽粒最大灌浆速率和灌浆速率最大时的生长量,促进了籽粒灌浆,最终夏玉米产量显著增加.

以黄淮海区普通玉米国家区域试验的对照品种郑单958为试验材料,设67500、82500株/hm22个种植密度水平和0、180、270 kg/hm23个施氮量水平,研究种植密度及施氮量对夏玉米淀粉粒分布及淀粉糊化特性的影响.试验结果表明,种植密度、施氮量单因子及其交互作用对玉米淀粉粒的体积分布存在显著影响,且施氮量是影响淀粉粒体积分布的主要因素.增加施氮量,<3.5μm与3.5～7.4μm淀粉粒体积比下降,>7.4μm淀粉粒体积比增加;随着氮肥用量增加,籽粒产量、粒重、总淀粉含量、支链淀粉含量,以及玉米淀粉的峰值黏度、谷值黏度、最终黏度、崩解值、回复值增加;相反,籽粒直链淀粉含量、直/支比以及玉米淀粉的峰值时间、糊化温度降低.种植密度与施氮量对淀粉粒体积分布的影响效果相反.该研究中,在种植密度82500株/hm2、氮肥用量270 kg/hm2条件下,玉米籽粒淀粉平均粒径较大,大型淀粉粒比例较高,其糊化特性和淀粉组成较优,且能兼顾籽粒产量.