Effects of Slow-release Nitrogen Fertilizer on Yield and Nitrogen Accumulation of Summer Maize in Shajiang Black Soil Area

[Objectives] This study was conducted to verify the field application effect of slow-release nitrogen fertilizer on summer maize in Shajiang black soil area by simultaneous sowing and fertilization, and explore the application scope and nitrogen metabolism mechanism, so as to lay a foundation for fertilizer reduction and efficiency improvement. [Methods] With maize variety Beiqing 340 and sulfur-coated urea as experimental materials, five nitrogen application levels were set, namely, control (C0), slow-release nitrogen 70 kg/hm^(2) (C70), slow-release nitrogen 140 kg/hm^(2) (C140), slow-release nitrogen 210 kg/hm^(2) (C210) and slow-release nitrogen 280 kg/hm^(2) (C280). The phosphorus and potassium fertilizers were all in accordance with the unified standard. [Results] With the application rate of slow-release nitrogen increasing, the nitrogen accumulation in organs increased first and then decreased after tasseling stage of maize. In order to reduce the fertilizing amount and increase efficiency, 210 kg/hm^(2) of slow-release nitrogen fertilizer was the best fertilizing amount for summer maize in Shajiang black soil area. [Conclusions] This study provides reference for fertilizer reduction, efficiency improvement and sustainable development of summer maize in Shajiang black soil area.

Effects of Slow-release Nitrogen on Dry Matter Accumulation,Translocation and Yield of Summer Maize

[Objectives]This study was conducted to investigate the effects of slow-release nitrogen fertilizer on dry matter accumulation and translocation of summer maize.[Methods]With Zhoudan 9 as the test variety,six different treatment were set up:blank control(CK1),slow-release urea 75 kg/hm^(2)(C1),slow-release urea 150 kg/hm^(2)(C2),slow-release urea 225 kg/hm^(2)(C3),slow-release urea 300 kg/hm^(2)(C4)and ordinary urea 300 kg/hm^(2)(CK2),to study the change law of dry matter accumulation and translocation in summer maize.[Results]Treatment slow-release urea 225 kg/hm^(2)(C4)showed summer maize yield,dry matter translocation between organs,grain contribution rate and proportion of grain dry matter in the full ripe stage higher than other treatments.Considering the weight loss and cost factors,slow-release urea 225 kg/hm^(2)(C3)could be recommended as the fertilizing amount for summer maize.[Conclusions]This study provides theoretical reference for rational selection of fertilizers for reducing fertilizer application and increasing fertilizer efficiency,and for production of summer maize in Shajiang black soil region.

Combined effects of high temperature and waterlogging on yield and stem development of summer maize

The purpose of this study was to identify the physiological mechanism underlying the effects of high temperature and waterlogging on summer maize.The stem development and yield of the maize hybrid Denghai 605 in response to high-temperature stress,waterlogging stress,and their combination applied for six days at the third-leaf,sixth-leaf,and tasseling stages were recorded.The combined stresses reduced lignin biosynthetic enzyme activity and lignin accumulation,leading to abnormal stem development.Reduction of the area and number of vascular bundles in stems led to reduced dry matter accumulation and allocation.Decreased grain dry weight at all three stages reduced grain yield relative to a control.In summary,high temperature,waterlogging,and their combined stress impaired stem development and grain yield of summer maize.The combined stresses were more damaging than either stress alone.

Identifying the critical phosphorus balance for optimizing phosphorus input and regulating soil phosphorus effectiveness in a typical winter wheat-summer maize rotation system in North China

Phosphorus(P)is a nonrenewable resource and a critical element for plant growth that plays an important role in improving crop yield.Excessive P fertilizer application is widespread in agricultural production,which not only wastes phosphate resources but also causes P accumulation and groundwater pollution.Here,we hypothesized that the apparent P balance of a crop system could be used as an indicator for identifying the critical P input in order to obtain a high yield with high phosphorus use efficiency(PUE).A 12-year field experiment with P fertilization rates of 0,45,90,135,180,and 225 kg P_(2)O_(5)ha^(-1)was conducted to determine the crop yield,PUE,and soil Olsen-P value response to P balance,and to optimize the P input.Annual yield stagnation occurred when the P fertilizer application exceeded a certain level,and high yield and PUE levels were achieved with annual P fertilizer application rates of 90-135 kg P_(2)O_(5)ha^(-1).A critical P balance range of 2.15-4.45 kg P ha^(-1)was recommended to achieve optimum yield with minimal environmental risk.The critical P input range estimated from the P balance was 95.7-101 kg P_(2)O_(5)ha^(-1),which improved relative yield(>90%)and PUE(90.0-94.9%).In addition,the P input-output balance helps in assessing future changes in Olsen-P values,which increased by 4.07 mg kg^(-1)of P for every 100 kg of P surplus.Overall,the P balance can be used as a critical indicator for P management in agriculture,providing a robust reference for limiting P excess and developing a more productive,efficient and environmentally friendly P fertilizer management strategy.

Effect of N Fertilization on Yield, N Absorption and Utilization of Two Species of Super High-Yielding Summer Maize

[Objective] The aim was to study on effects of N fertilizer on yield, N absorption and utilization of different cultivars of super high-yielding summer maize, in order to provide reference for reasonable N fertilization in accordance with different cultivars. [Method] Field experiment was conducted to study on effects of different N fertilizers on yield, N absorption and use efficiency of Zhengdan 958 and Xundan 20, in order to learn the effect differences at different N fertilizer levels. [Result] After N was applied, yields of the two summer maize increased significantly. Zhengdan 958 achieved the highest in yield and proceeds at 12 051.18 kg/hm2 and 1 722.40 yuan/hm2, respectively in low N level. In contrast, Xundan 20 achieved the highest at 13 166.00 kg/hm2 and 1 343.92 yuan/hm2 in the above two aspects in high N level. Compared with Zhengdan 958, Xundan 20 increased by 9.90%, 5.20% and 12.00% in N levels of 0, 240, and 450 kg/hm2, respectively. When N fertilizers were applied, protein yield of Xundan 20 was significantly higher than that of Zhengdan 958, so that higher N fertilizers contributed higher protein yield for Xundan 20. In high N level, N efficiency, N-fertilizer utilization and partial productivity of Xundan 20 were significantly higher than that of Zhengdan 958. [Conclusion] Lower N-fertilizer was suitable for Zhengdan 958 and Xundan 20 would get a good harvest if more N-fertilizers were applied. The results provided references for reasonable N fertilization.

Effects of Planting Density and Nitrogen Amount on Stalk Lodging-Resistance and Yield of Summer Maize in Sichuan Basin

[Objective] The experiment was conducted to explore the suitable planting density and nitrogen amount for summer maize in Sichuan Basin with the objective to provide technical reservation and scientific basis for high-yielding cultivation technique.[Method] A widely planted maize cultivar ＇Chengdan 30＇ was used as experimental material to study the effects of planting density and nitrogen amount on the stalk agronomic traits,stalk lodging-resistance mechanical characters,stalk breaking percentage and yield of maize.Experiment was arranged in a two-factor split plot design with three replicates.The planting density was the main factor with three density gradients（4.5×10^4,6.0×10^4 and 7.5×10^4 plants/hm^2） and the nitrogen amount was the second factor with two different levels of nitrogen content（300 and 375 kg/hm^2）.[Result] The stalk lodging-resistance and yield were affected by planting density significantly.The increase of planting density would result in an increase of internode length and decrease of internode diameter,dry matter weight of per unit stalk length,rind penetration strength and breaking resistance of 3rd and 4th basal internodes.When planting density increased from 6.0×10^4 plants/hm2 to 7.5×10^4 plants/hm^2,the stalk breaking percentage in the whole growing season increased by 17.17%,and the yield reduced by 17.58%.The interaction between planting density and nitrogen amount affected the stalk breaking percentage in the whole growing season and yield significantly.The treatment with planting density of 6.0×104 plants/hm^2 and nitrogen amount of 375 kg/hm^2 of pure N was an optimal combination,which may not only control the stalk breaking percentage of whole growing stage effectively,but also could obtain an optimum grain yield.[Conclusion] In Sichuan Basin,the appropriate planting density and nitrogen amount for summer maize were 6.0×10^4 plants/hm^2 and 375 kg/hm^2.

Effects of a New Long-term Controlled-release Fertilizer on Growth and Development and Yield of Summer Maize

[Objective] The aim was to select the optimal amount of controlled-release fertilizer and provide theoretical references for controlled-release fertilizers use in summer maize. [Method] Long-term controlled-release fertilizers were applied once at sowing summer maize to explore effects on maize growth, yield, economic profits and environment. [Result] Maize yield reduced a little in the treatment group with 60% CRF, and increased in varying degrees in the rest groups in the range of 1.1%-7.4%, and some showed significant differences. [Conclusion] Controlled-release fertilizers can be applied once at the amount of 80% common fertilizer＇s, with con- sideration of maize yield, nitrogen use rate and economic profits, which is beneficial for summer maize application and promotion in North China.

Effects of Postponing N Application on Metabolism,Absorption and Utilization of Nitrogen of Summer Maize in SuperHigh Yield Region

[Objective] The aim was to explore effects of application postponing of N fertilizer and the mechanism of yield increase in order to provide references for N fertilizer application in a rational way. [Method] In a super-high yielded region of summer maize, field experiment was conducted to research effects of N fertilizer postponing on key enzymes of N metabolism, yield of maize and N fertilizer use. [Result] After application of N fertilizer was postponed, NR, SPS and GS activities of ear-leaf of summer maize increased by 11.99%-34.87%, 8.25%-10.64% and 10.00%- 16.81% on the 28^th d of silking; content of soluble sugar in leaves enhanced signifi- cantly and accumulated nitrogen increased by 5.00%-9.74% in mature stage. The postponing fertilization of ＂30% of fertilizer in seedling stage＋30% of fertilizer in flare- opening stage＋40% of fertilizer in silking stage meets N demands of summer maize in late growth period. Compared with conventional fertilization, the maize yield, agro- nomic efficiency and use of N fertilizer all improved by 5.05%, 1.75 kg/kg and 6.87%, respectively, after application postponed. [Conclusion] Application postponing of N fertilizer maintains activity of NR, GS and SPS higher and coordinates metabolism of C and N in late growth period, to further improve yield of maize.

Effects of Controlled-Release Nitrogen on Yield and Nitrogen Use Efficiency of Summer Maize

The field experiments were conducted in Anhui during 2016 to investigate the effects of controlled-release nitrogen （CRN） rates and mixture of controlled-re- lease nitrogen and conventional nitrogen （CN） on the yield and nitrogen efficiency of summer maize. Six treatments included CK （with no application of N）, CNIO0% splits （CN）, CRFIO0% （CRN1）, CRN60%＋CN40% （CRN2）, CRN85% （CRN3） and CRN70% （CRN4）. The results showed proper CRN increased yields and output val- ue. Compared with CN, CRN2 significantly increased by 13.74%, CRN1 increased by 4.84%, and CRN3 was equal to CN. CRN increased yield by grain number per spike of yield components. CRN2 had the highest apparent nitrogen fertilizer recov- ery efficiency and CRN1 was the second, which were significantly higher than CN. Nitrogen agronomic efficiency of CRN2 was significantly higher than CN. Nitrogen physiological efficiency of CRN2 was higher than CN. The partial productivity of CRN1 was higher than that with CN. And the effect of nitrogen fertilizer of CRN2 was the highest, which was increased 758 yuan/hm2. Considering yield, nitrogen use efficiency and economic benefit, applying the mixture of CRN and CN was the most beneficial treatment. CRN1 was the second treatment, and CRN3 didn＇t reduce yield.

Effects of saline irrigation on soil salt accumulation and grain yield in the winter wheat-summer maize double cropping system in the low plain of North China

In the dominant winter wheat （WW）-summer maize （SM） double cropping system in the low plain located in the North China, limited access to fresh water, especially during dry season, constitutes a major obstacle to realize high crop productivity. Using the vast water resources of the saline upper aquifer for irrigation during WW jointing stage, may help to bridge the peak of dry season and relieve the tight water situation in the region. A field experiment was conducted during 2009-2012 to investigate the effects of saline irrigation during WW jointing stage on soil salt accumulation and productivity of WW and SM. The experiment treatments comprised no irrigation （T1）, fresh water irrigation （T2）, slightly saline water irrigation （T3：2.8 dS m-l）, and strongly saline water irrigation （T4：8.2 dS m-1） at WW jointing stage. With regard to WW yields and aggregated annual WW-SM yields, clear benefits of saline water irrigation （T3 ＆ T4） compared to no irrigation （T1）, as well as insignificant yield losses compared to fresh water irrigation （T2） occurred in all three experiment years. However, the increased soil salinity in eady SM season in consequence of saline irrigation exerted a negative effect on SM photosynthesis and final yield in two of three experiment years. To avoid the negative aftereffects of saline irrigation, sufficient fresh water irrigation during SM sowing phase （i.e., increase from 60 to 90 mm） is recommended to guarantee good growth conditions during the sensitive early growing period of SM. The risk of long-term accumulation of salts as a result of saline irrigation during the peak of dry season is considered low, due to deep leaching of salts during regularly occurring wet years, as demonstrated in the 2012 experiment year. Thus, applying saline water irrigation at jointing stage of WW and fresh water at sowing of SM is most promising to realize high yield and fresh irrigation water saving.

Water consumption in summer maize and winter wheat cropping system based on SEBAL model in Huang-Huai-Hai Plain, China

Crop consumptive water use is recognized as a key element to understand regional water management performance. This study documents an attempt to apply a regional evapotranspiration model（SEBAL） and crop information for assessment of regional crop（summer maize and winter wheat） actual evapotranspiration（ET a） in Huang-Huai-Hai（3H） Plain, China. The average seasonal ET a of summer maize and winter wheat were 354.8 and 521.5 mm respectively in 3H Plain. A high-ET a belt of summer maize occurs in piedmont plain, while a low ET a area was found in the hill-irrigable land and dry land area. For winter wheat, a high-ET a area was located in the middle part of 3H Plain, including low plain-hydropenia irrigable land and dry land, hill-irrigable land and dry land, and basin-irrigable land and dry land. Spatial analysis demonstrated a linear relationship between crop ET a, normalized difference vegetation index（NDVI）, and the land surface temperature（LST）. A stronger relationship between ET a and NDVI was found in the metaphase and last phase than other crop growing phase, as indicated by higher correlation coefficient values. Additionally, higher correlation coefficients were detected between ET a and LST than that between ET a and NDVI, and this significant relationship ran through the entire crop growing season. ET a in the summer maize growing season showed a significant relationship with longitude, while ET a in the winter wheat growing season showed a significant relationship with latitude. The results of this study will serve as baseline information for water resources management of 3H Plain.

Increased plant density and reduced N rate lead to more grain yield and higher resource utilization in summer maize

Planting at an optimum density and supplying adequate nitrogen（N） to achieve higher yields is a common practice in crop production, especially for maize（Zea mays L.）; however, excessive N fertilizer supply in maize production results in reduced N use efficiency（NUE） and severe negative impacts on the environment. This research was conducted to determine the effects of increased plant density and reduced N rate on grain yield, total N uptake, NUE, leaf area index（LAI）, intercepted photosynthetically active radiation（IPAR）, and resource use efficiency in maize. Field experiments were conducted using a popular maize hybrid Zhengdan 958（ZD958） under different combinations of plant densities and N rates to determine an effective approach for maize production with high yield and high resource use efficiency. Increasing plant density was clearly able to promote N absorption and LAI during the entire growth stage, which allowed high total N uptake and interception of radiation to achieve high dry matter accumulation（DMA）, grain yield, NUE, and radiation use efficiency（RUE）. However, with an increase in plant density, the demand of N increased along with grain yield. Increasing N rate can significantly increase the DMA, grain yield, LAI, IPAR, and RUE. However, this increase was non-linear and due to the input of too much N fertilizers, the efficiency of N use at NCK（320 kg ha^（–1）） was low. An appropriate reduction in N rate can therefore lead to higher NUE despite a slight loss in grain production. Taking into account both the need for high grain yield and resource use efficiency, a 30% reduction in N supply, and an increase in plant density of 3 plants m^（–2）, compared to LD（5.25 plants m^（–2））, would lead to an optimal balance between yield and resource use efficiency.

Modified fertilization management of summer maize(Zea mays L.) in northern China improves grain yield and efficiency of nitrogen use

Improving the yield of maize grain per unit area is needed to meet the growing demand for it in China, where the availability of fertile land is very limited.Modified fertilization management and planting density are efficient methods for increasing crop yield.Field experiments were designed to investigate the influence of modified fertilization management and planting density on grain yield and nitrogen use efficiency of the popular maize variety Zhengdan 958, in four treatments including local farmer＇s practice（FP）, high-yielding and high efficiency cultivation（HH）, super high-yielding cultivation（SH）, and the control（CK）.Trials were conducted in three locations of the Huang-Huai-Hai Plain in northern China.Compared with FP, SH was clearly able to promote N absorption and dry matter accumulation in post-anthesis, and achieve high yield and N use efficiency by increasing planting density and postponing the supplementary application of fertilizers.However, with an increase in planting density, the demand of N increased along with grain yield.Due to the input of too much N fertilizer, the efficiency of N use in SH was low.Applying less total N, ameliorating cultivation and cropping management practices should be considered as priority strategies to augment production potential and finally achieve synchronization between high yield and high N efficiency in fertile soils.However, in situations where soil fertility is low, achieving high yield and high N use efficiency in maize will likely depend on increased planting density and appropriate application of supplementary fertilizers postpone to the grain-filling stage.

Evaluation of Pathway of Nitrogen Loss in Winter Wheat and Summer Maize Rotation System

The nitrogen loss pathway in winter wheat and summer maize rotation system was studied based on field experimental data. The results showed that nitrogen recovery rate was significantly decreased with nitrogen fertilization rate increased, while residual rate and losses rate had an increasing trend. Accumulated ammonia volatilization loss in winter wheat and summer maize rotation was 12. 8(N0), 22.0(N120), 33. 0(N240) and 64. 5 kg N ha-1 (N360) respectively and rate of ammonia volatilization loss was 3.8, 4.2 and 7.2% respectively while urea was mixed with 0 -10 cm soil or spread before irrigation. Denitrification loss with acetylene-soil core incubation method in winter wheat was lower than 1 kg N ha-1 and rate of denitrification loss was 0. 21 - 0. 26% or trace. Denitrification loss in summer maize was 1 - 14 kg N ha-1 and rate of denitrification loss was 1-5%. The total gaseous loss in winter wheat and summer maize rotation system was less than 10%, and the main nitrogen fertilizer loss way was leaching below 0 - 100 cm soil profile and accumulated in deeper soil.

Effects of urea mixed with nitrapyrin on leaf photosynthetic and senescence characteristics of summer maize(Zea mays L.)waterlogged in the field

Waterlogging is one of the major abiotic stresses in agricultural crop production.However,the application of 2-chloro-6-(trichloromethyl)pyridine(nitrapyrin)can effectually mitigate the losses of nitrogen efficiency and grain yield of summer maize induced by waterlogging.In order to explore its role to alleviate waterlogging stress on leaf antioxidative system and photosynthetic characteristics of summer maize,a field experiment was executed to research effects of nitrapyrin application on leaf photosynthetic and senescent characteristics of waterlogged summer maize Denghai 605(DH605)and Zhengdan 958(ZD958).Experimental treatments consisted of waterlogging treatment that was applying only urea(WL),waterlogging treatment that was applying urea mixing with nitrapyrin(WL-N),and no waterlogging treatment that was only applying urea(NWL).Results showed that WL significantly decreased leaf area index(LAI),SPAD,photosynthetic rate(Pn),and protective enzyme activities,accelerated leaf aging,eventually led to a remarkable yield reduction by 38 and 42%for DH605 and ZD958,respectively,compared to NWL.However,the application of nitrapyrin was useful for relieving waterlogging damages on leaf photosynthetic ability.LAI,SPAD and Pn of WL-N for DH605 were 10,19 and 12-24%higher,and for ZD958 were 12,23 and 7-25%higher,compared to those of WL,respectively.Moreover,application of nitrapyrin effectually relieved waterlogging losses on antioxidative enzyme activities.Leaf superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)activities of WL-N were averagely increased by 24,15 and 30%,respectively,while malondialdehyde(MDA)content was averagely decreased by 13%,compared to those of WL.Visibly,nitrapyrin application could improve leaf photosynthetic characteristics and retard leaf aging induced by waterlogging,thereby leading to a yield increase of waterlogged maize.

Effects of Illumination Intensity, 5-aminolevulinic Acid Concentration and Their Interaction on Chlorophyll Fluorescence Parameters and Yield of Summer Maize

[Objective] This study aimed to investigate the influence of illumination intensity, 5-aminolevulinic acid （ALA） concentration and their interaction on chlorophyll fluorescence parameters and yield of summer maize. [Method] Two illumination intensity levels and five ALA concentrations were applied in the experiment using 2x5 completely balanced program. The two illumination intensity levels were natural light （So） and 60% shade （SO, and five ALA concentrations were 0, 1, 10, 25 and 50 mg/L. [Result] The relative chlorophyll content of leaf （SPAD）, the optimal/maximal quantum yield of PS II （Fv/Fm）, the photochemical quenching coefficient （qP）, electron transport rate （ETR）, grain number per cob and grain weight per cob in $1 treatment were significantly reduced compared with that in So. However, the non- photochemical quenching coefficient （qN） was significantly increased. The responses of these parameters to ALA were different under So and $1 treatments. The SPAD, Fv/Fm, qP, ETR, grain number and grain weight per cob were firstly increased, but then decreased following the raise of ALA concentration, ranging from 0 to 50 mg/L, whereas qN showed opposite trend. The effect of the interaction of illumination in- tensity and ALA concentration on these parameters was significant （P〈0.05）. Under natural light, summer maize could obtain higher SPAD, Fv/Fm, qP and ETR and lower qN combined with low concentration of ALA. However, high concentration of ALA was needed under shading to get the same results. [Conclusion] Soaking seed in suitable concentration of ALA can reduce the yield loss of summer maize caused by short-term shading in seedling stage.

Effects of Nitrogen Fertilizer on Yield, Nitrogen Absorption and Utilization on Four Summer Maize Species

[Objective] The aim was to explore scientific application of N fertilizer for summer maize species.[Method] A test was designed to research effects of N quantities on Zhengdan No.958,Xundan No.20,Nonghua No.101 and Xianyu No.335 in terms of yield,economic benefits,accumulated nitrogen and use efficiency of N fertilizer.[Result] The increase of N fertilizer improved yields of summer maize dramatically.Specifically,with low N quantity,yield and net revenue of Zhengdan No.958 reached 18.19% and 3 158 yuan/hm^2,respectively,and yields and net revenues of Jundan No.20,Nonghua No.101 and Xianyu No.335 were 17.31% and 2 642 yuan/hm^2,25.03% and 3 726 yuan/hm^2,17.41% and 3 182 yuan/hm^2,accordingly.With N quantity increased,agricultural efficiency of Zhengdan No.958 reduced significantly and the agricultural efficiencies showed little differences among Xundan No.20,Nonghua No.101 and Xianyu No.335.[Conclusion] In practice,Zhengdan No.958 is suitable to be applied with N at low quantity,and Xundan No.20,Nonghua No.101 and Xianyu No.335 are suitable to be applied with N at high quantity.

Effects of mulches on water use in a winter wheat/summer maize rotation system in Loess Plateau, China

Limited water resources often result in reduced crop yield and low water productivity（WP）. In northwestern China, crop production is generally dependent on precipitation. Therefore, a variety of agricultural rainwater harvesting（ARH） techniques have been used for conserving soil moisture, ameliorating soil environment, increasing crop yield, and improving water use efficiency. A two-year（2013–2015） field experiment was conducted under a typical sub-humid drought-prone climate in Yangling（108°24′E, 34°20′N; 521 m a.s.l.）, Shaanxi Province, China, to explore the effects of mulching（same for summer maize and winter wheat） on soil moisture, soil temperature, crop water consumption, and crop yield with a winter wheat/summer maize rotation. Crops were planted in a ridge-furrow pattern and the treatments consisted of a transparent film mulch over the ridges（M1）, a crop straw mulch in the furrows（M2）, a transparent film mulch over the ridges and a crop straw mulch in the furrows（M3）, a black film mulch over the ridges and a crop straw mulch in the furrows（M4）, and a control with no mulch（CK）. Results showed that M4 was the best treatment for improving soil water storage and content, and decreasing crop water consumption during the summer maize and winter wheat rotation. In both maize and wheat seasons, M1 had a higher soil temperature than M2 and CK, and M3 had a higher soil temperature than M4. In the maize seasons, M4 had the highest yield, WP, and precipitation productivity（PP）, with the average values for these parameters increasing by 30.9%, 39.0%, and 31.0%, respectively, compared to those in CK. In the wheat seasons, however, M3 had the highest yield, WP, and PP, with the average values for these parameters being 23.7%, 26.7%, and 23.8% higher, respectively, than those in CK. Annual yield（maize and wheat yields combined） and WP did not differ significantly between M3 and M4. These results suggested that M3 and M4 may thus be the optimal ARH practices for the production of winter wheat and summer maize, respectively, in arid and semi-arid areas.

The effect of elevating temperature on the growth and development of reproductive organs and yield of summer maize

Compared to other crops,maize production demands relatively high temperatures.However,temperatures exceeding 35℃lead to adverse effects on maize yield.High temperatures(≥35℃)are consistently experienced by summer maize during its reproductive growth stage in the North China Plain,which is likely to cause irreversible crop damage.This study investigated the effects of elevating temperature(ET)treatment on the yield component of summer maize,beginning at the 9th unfolding leaf stage and ending at the tasseling stage.Results demonstrated that continuous ET led to a decrease in the elongation rate and activity of silks and an elongated interval between anthesis and silking stages,and eventually decreased grain number at ear tip and reduced yield.Although continuous ET before tasseling damaged the anther structure,reduced pollen activity,delayed the start of the pollen shedding stage,and shortened the pollen shedding time,it was inferred,based on phenotypical and physiological traits,that continuous ET after the 9th unfolding leaf stage influenced ears and therefore may have more significant impacts.Overall,when maize plants were exposed to ET treatment in the ear reproductive development stage,the growth of ears and tassels was blocked,which increased the occurrence of barren ear tips and led to large yield losses.

Poor development of spike differentiation triggered by lower photosynthesis and carbon partitioning reduces summer maize yield after waterlogging

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 10 th 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.