Effect of Different Winter Cover Crops on Carbon Dioxide Emission in Paddy Field of Double Cropping Rice Area in Southern China

In this study, a two-year experiment was conducted by suing a static chamber method to observe the effects of straw recycling of winter cover crops measure on CO2 emission fluxes in southern China. Three patterns of winter use were performed in the paddy field, including RRR （rice-rice-ryegrass （Lolium multiflorum L.） cropping system）, CRR （rice-rice-Chinese milk vetch （Astragalus sinicus L.） cropping system） and FRR （rice-rice cropping system with winter fallow）. During the winter, the average daily CO2 fluxes were greater （P 〈 0.05） in the RRR and CRR than the FRR. During the winter crop growing seasons, both the average daily CO2 fluxes and the total CO2 emissions were different as the following orders： RRR 〉 CRR 〉 FRR. The average CO2 fluxes during early rice and late rice season were similar. The highest CO2 flux was found at rice tillering stage with an order as the follows： RRR 〉 CRR 〉 FRR and CRR 〉 RRR 〉 FRR both in 2009 and 2010, respectively. The annual CO2 emissions of RRR and CRR were significantly higher respectively by 857.0 g.CO2-C.m2 and 607.4 g.CO2-C.m-2 than the FRR. The results show that straw recycling of winter cover crops measure may strongly influence the CO2 emission in paddy field in southern China.

Non-leguminous winter cover crop and nitrogen rate in relation to double rice grain yield and nitrogen uptake in Dongting Lake Plain, Hunan Province, China

Annual ryegrass（Lolium multiflorum Lam.）, a non-leguminous winter cover crop, has been adopted to absorb soil native N to minimize N loss from an intensive double rice cropping system in southern China, but a little is known about its effects on rice grain yield and rice N use efficiency. In this study, effects of ryegrass on double rice yield, N uptake and use efficiency were measured under different fertilizer N rates. A 3-year（2009–2011） field experiment arranged in a split-plot design was undertaken. Main plots were ryegrass（RG） as a winter cover crop and winter fallow（WF） without weed. Subplots were three N treatments for each rice season： 0（N_0）, 100（N_（100）） and 200 kg N ha–1（N_（200））. In the 3-year experiment, RG reduced grain yield and plant N uptake for early rice（0.4–1.7 t ha–1 for grain yield and 4.6–20.3 kg ha–1 for N uptake） and double rice（0.6–2.0 t ha–1 for grain yield and 6.3–27.0 kg ha–1 for N uptake） when compared with WF among different N rates. Yield and N uptake decrease due to RG was smaller in N_（100） and N_（200） plots than in N_0 plots. The reduction in early rice grain yield in RG plots was associated with decrease number of panicles. Agronomic N use efficiency and fertilizer N recovery efficiency were higher in RG plots than winter fallow for early rice and double rice among different N rates and experimental years. RG tended to have little effect on grain yield, N uptake, agronomic N use efficiency, and fertilizer N recovery efficiency in the late rice season. These results suggest that ryegrass may reduce grain yield while it improves rice N use efficiency in a double rice cropping system.

Effects of Winter Cover Crop and Straw Returning on the Functional Diversity of Rhizosphere Microflora in Double-crop Rice Paddies

The functional diversity of rhizosphere microflora which is also known as the “microbial community” is a sensitive indicator of soil quality subject to the type of winter cover crop and straw returning.In order to evaluate the effects of different winter cover crops and returning patterns on the functional diversity of rhizosphere microflora in double-crop rice paddies,we designed five winter cover crops and straw returning combinations to analyze their effects on the functional diversity of rhizosphere microflora in rice paddies: ryegrass (Lolium multiflorumL.)–double-crop rice (Ry),milk vetch (Astragalus sinicus L.)–double-crop rice (Mv),Rape (Brassica napus L.)–Double-crop rice (Ra), Potato (Solanum tuberosum L.)–double-crop rice (Po),and winter fallow–doublecrop rice (CK,the control).In this paper,the average well color development (AWCD) in Biolog-GN plates indicated the capacity for carbon utilization by the rhizosphere microbial community.We analyzed the rhizosphere microbial community functional diversity of the paddy soils with the above five treatments by using the Biolog-GN system.The results showed that applications of winter cover crop and straw returning caused high increases in AWCD compared with CK,and the AWCD values for samples with Po treatment was greater than those with Ry and CK treatments at the early and late rice maturity stages. It was concluded that applications of winter cover crop and straw returning can cause changes in the carbon utilization efficiency of rhizosphere microflora.There were differences in the genetic diversity of the rhizosphere microflora among different treatments at the maturity stage of early and late rice.The richness,Shannon,and McIntosh Index under different winter cover crop and straw returning treatments were significantly different.The highest indexes were observed in the Po treatment and the lowest in the CK at the maturity stage of early and late rice.The richness, Shannon,and McIntosh Index under different treatments ranked in descending order is as follows: Po>Ra>Mv>Ry>CK.Principal Component Analysis (PCA) of substrate reactions were conducted in this research.The results indicated that the pattern of carbon source utilization varied with winter cover crop treatments,and that carbohydrates and amino acids were the main carbon sources of rhizosphere microorganisms.To conclude,the application of winter cover crop and straw returning to paddy fields could significantly increase the carbon source utilization, species richness,and species evenness of rhizosphere microflora in double-crop rice paddies.

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.

A simulation of winter wheat crop responses to irrigation management using CERES-Wheat model in the North China Plain

To improve efficiency in the use of water resources in water-limited environments such as the North China Plain（NCP）, where winter wheat is a major and groundwater-consuming crop, the application of water-saving irrigation strategies must be considered as a method for the sustainable development of water resources. The initial objective of this study was to evaluate and validate the ability of the CERES-Wheat model simulation to predict the winter wheat grain yield, biomass yield and water use efficiency（WUE） responses to different irrigation management methods in the NCP. The results from evaluation and validation analyses were compared to observed data from 8 field experiments, and the results indicated that the model can accurately predict these parameters. The modified CERES-Wheat model was then used to simulate the development and growth of winter wheat under different irrigation treatments ranging from rainfed to four irrigation applications（full irrigation） using historical weather data from crop seasons over 33 years（1981–2014）. The data were classified into three types according to seasonal precipitation： 〈100 mm, 100–140 mm, and 〉140 mm. Our results showed that the grain and biomass yield, harvest index（HI） and WUE responses to irrigation management were influenced by precipitation among years, whereby yield increased with higher precipitation. Scenario simulation analysis also showed that two irrigation applications of 75 mm each at the jointing stage and anthesis stage（T3） resulted in the highest grain yield and WUE among the irrigation treatments. Meanwhile, productivity in this treatment remained stable through different precipitation levels among years. One irrigation at the jointing stage（T1） improved grain yield compared to the rainfed treatment and resulted in yield values near those of T3, especially when precipitation was higher. These results indicate that T3 is the most suitable irrigation strategy under variable precipitation regimes for stable yield of winter wheat with maximum water savings in the NCP. The application of one irrigation at the jointing stage may also serve as an alternative irrigation strategy for further reducing irrigation for sustainable water resources management in this area.

Study on Growth Monitoring and Yield Prediction of Winter Wheat in the South of Shanxi Province Based on MERSI Data and ALMANAC Crop Model

Accurate crop growth monitoring and yield forecasting have important implications for food security and agricultural macro-control. Crop simulation and satellite remote sensing have their own advantages, combining the two can improve the real-time mechanism and accuracy of agricultural monitoring and evaluation. The research is based on the MERSI data carried by China’s new generation Fengyun-3 meteorological satellite, combined with the US ALMANAC crop model, established the NDVI-LAI model and realized the acquisition of LAI data from point to surface. Because of the principle of the relationship between the morphological changes of LAI curve and the growth of crops, an index that can be used to determine the growth of crops is established to realize real-time, dynamic and wide-scale monitoring of winter wheat growth. At the same time, the index was used to select the different key growth stages of winter wheat for yield estimation. The results showed that the relative error of total yield during the filling period was low, nearly 5%. The research results show that the combination of domestic meteorological satellite Fengyun-3 and ALMANAC crop model for crop growth monitoring and yield estimation is feasible, and further expands the application range of domestic satellites.

应用ARID CROP模型对中国黄淮海地区冬小麦气候生产力的数值模拟研究

应用ＡＲＩＤＣＲＯＰ模型对黄淮海地区冬小麦气候生产力进行了数值模拟研究，给出了该地区冬小麦气候生产力Ｙｑ分布图，继而研究了水分保持最适状况时的光温生产力Ｙｗ分布状况，在此基础上给出了水分增产力Ｑ（Ｑ＝（Ｙｗ－Ｙｑ）／Ｙｑ）分布图。研究表明，黄淮海地区冬小麦气候生产力变幅在３７５０～９７５０ｋｇ／ｈｍ２之间，总的趋势北低南高，黑龙港地区出现了一个３７５０ｋｇ／ｈｍ２的低值区。水分是黄淮海北部地区冬小麦气候生产力的一个重要限制因子，当水分完全适宜时，南部淮河流域冬小麦气候生产力仅可提高５％～１０％，而黄淮海北部地区气候生产力则可提高７５％～１００％。用黄淮海地区冬小麦高产记录与生产力模拟值进行了对比分析，表明用ＡＲＩＤＣＲＯＰ模型对该地区冬小麦气候生产力进行研究是可行的，该研究为引黄灌溉提供了一定的理论依据。

Effect of various crop rotations on rice yield and nitrogen use efficiency in paddy–upland systems in southeastern China

To evaluate the effects of various rotation systems on rice grain yield and N use efficiency, a paddy–upland cropping experiment(2013–2016) was conducted in southeastern China. The experiment was designed using six different rice––winter crop rotations: rice–fallow(RF),rice–wheat(RW), rice–potato with rice straw mulch(RP), rice–green manure(Chinese milk vetch; RC–G), rice–oilseed rape(RO), and rice–green manure crop(oilseed rape with fresh straw incorporated into soil at flowering; RO–G) and three N rates, N0(0 kg N ha-1), N1(142.5 kg N ha-1), and N2(202.5 kg N ha-1). Average rice yields in the RF(5.93 t ha-1) rotation were significantly lower than those in the rotations with winter crops(7.20–7.48 t ha-1)under the N0 treatment, suggesting that incorporation of straw might be more effective for increasing soil N than winter fallow. The rice yield differences among the rotations varied by year with the N input. In general, the grain yields in the RP and RO–G rotations –were respectively 11.6–28.5% and 14.80–37.19% higher than those in the RF in plots with N applied. Increasing the N rate may have tended to minimize the average yield gap between the RF and the other rotations; the yield gaps were 18.55%, 4.14%, and 0.23% in N0, N1, and N2, respectively. However, the N recovery efficiency in the RF was significantly lower than that in other rotations, except for 2015 under both N1 and N2 rates, a finding that implies a large amount of chemical N loss. No significant differences in nitrogen agronomic efficiency(NAE) and physiological efficiency(NPE) were found between the rotations with legume(RC–G) and non–legume(RO and RW) winter crops, a result that may be due partly to straw incorporation. For this reason, we concluded that the return of straw could reduce differences in N use efficiency between rotations with and without legume crops. The degree of synchrony between the crop N demand and the N supply was evaluated by comparison of nitrogen balance degree(NBD) values. The NBD values in the RP and RW were significantly lower than those in the other rotations under both N1 and N2 rates. Thus,in view of the higher grain yield in the RP compared to the RW under the N1 rate, the RP rotation might be a promising practice with comparable grain yield and greater N use efficiency under reduced N input relative to the other rotations. The primary yield components of the RF and RP were identified as number of panicles m-2 and numbers of kernels panicle-1, respectively. The NAE and NPE were positively correlated with harvest index, possibly providing a useful indicator for evaluating N use efficiency.

Significant reduction of ammonia emissions while increasing crop yields using the 4R nutrient stewardship in an intensive cropping system

Ammonia (NH_3) emissions should be mitigated to improve environmental quality.Croplands are one of the largest NH_3sources,they must be managed properly to reduce their emissions while achieving the target yields.Herein,we report the NH_3 emissions,crop yield and changes in soil fertility in a long-term trial with various fertilization regimes,to explore whether NH_3 emissions can be significantly reduced using the 4R nutrient stewardship (4Rs),and its interaction with the organic amendments (i.e.,manure and straw) in a wheat–maize rotation.Implementing the 4Rs significantly reduced NH_3 emissions to 6 kg N ha~(–1) yr~(–1) and the emission factor to 1.72%,without compromising grain yield (12.37 Mg ha~(–1) yr~(–1))and soil fertility (soil organic carbon of 7.58 g kg~(–1)) compared to the conventional chemical N management.When using the 4R plus manure,NH_3 emissions (7 kg N ha~(–1) yr~(–1)) and the emission factor (1.74%) were as low as 4Rs,and grain yield and soil organic carbon increased to 14.79 Mg ha~(–1) yr~(–1) and 10.09 g kg~(–1),respectively.Partial manure substitution not only significantly reduced NH_3 emissions but also increased crop yields and improved soil fertility,compared to conventional chemical N management.Straw return exerted a minor effect on NH_3 emissions.These results highlight that 4R plus manure,which couples nitrogen and carbon management can help achieve both high yields and low environmental costs.

Assimilation of temporal-spatial leaf area index into the CERES-Wheat model with ensemble Kalman filter and uncertainty assessment for improving winter wheat yield estimation

To accurately estimate winter wheat yields and analyze the uncertainty in crop model data assimilations, winter wheat yield estimates were obtained by assimilating measured or remotely sensed leaf area index （LAI） values. The performances of the calibrated crop environment resource synthesis for wheat （CERES-Wheat） model for two different assimilation scenarios were compared by employing ensemble Kalman filter （EnKF）-based strategies. The uncertainty factors of the crop model data assimilation was analyzed by considering the observation errors, assimilation stages and temporal-spatial scales. Overalll the results indicated a better yield estimate performance when the EnKF-based strategy was used to comprehen- sively consider several factors in the initial conditions and observations. When using this strategy, an adjusted coefficients of determination （R2） of 0.84, a root mean square error （RMSE） of 323 kg ha-1, and a relative errors （RE） of 4.15% were obtained at the field plot scale and an R2 of 0.81, an RMSE of 362 kg ha-1, and an RE of 4.52% were obtained at the pixel scale of 30 mx30 m. With increasing observation errors, the accuracy of the yield estimates obviously decreased, but an acceptable estimate was observed when the observation errors were within 20%. Winter wheat yield estimates could be improved significantly by assimilating observations from the middle to the end of the crop growing seasons. With decreasing assimilation frequency and pixel resolution, the accuracy of the crop yield estimates decreased; however, the computation time decreased. It is important to consider reasonable temporal-spatial scales and assimilation stages to obtain tradeoffs between accuracy and computation time, especially in operational systems used for regional crop yield estimates.

The Possible Effect of Climate Warming on Northern Limits of Cropping System and Crop Yield in China

Significantly increasing temperature since the 1980s in China has become a consensus under the background of global climate change and how climate change affects agriculture or even cropping systems has attracted more and more attention from Chinese government and scientists. In this study, the possible effects of climate warming on the national northern limits of cropping systems, the northern limits of winter wheat and double rice, and the stable-yield northern limits of rainfed winter wheat-summer maize rotation in China from 1981 to 2007 were analyzed. Also, the possible change of crop yield caused by planting limits displacement during the periods 1950s-1981 and 1981-2007 was compared and discussed. The recognized calculation methods of agricultural climatic indices were employed. According to the indices of climatic regionalization for cropping systems, the national northern limits of cropping systems, winter wheat and double rice, and the stable-yield northern limits of rainfed winter wheat-summer maize rotation during two periods, including the 1950s-1980 and 1981-2007, were drawn with ArcGIS software. Compared with the situation during the 1950s- 1980, the northern limits of double cropping system during 1981-2007 showed significant spatial displacement in Shaanxi, Shanxi, Hebei, and Liaoning provinces and Beijing municipality, China. The northern limits of triple cropping system showed the maximum spatial displacement in Hunan, Hubei, Anhui, Jiangsu, and Zhejiang provinces, China. Without considering variety change and social economic factors, the per unit area grain yield of main planting patterns would increase about 54-106% if single cropping system was replaced by double cropping system, which turned out to be 27- 58% if double cropping system was replaced by triple cropping system. In Liaoning, Hebei, Shanxi, Shaanxi, Gansu, and Qinghai provinces, Inner Mongolia and Ningxia autonomous regions, China, the northern limits of winter wheat during 1981-2007 moved northward and expanded westward in different degrees, compared with those during the 1950s-1980. Taking Hebei Province as an example, the northern limits of winter wheat moved northward, and the per unit area grain yield would averagely increase about 25% in the change region if the spring wheat was replaced by winter wheat. In Zhejiang, Anhui, Hubei, and Hunan provinces, China, the planting northern limits of double rice moved northward, and the per unit area grain yield would increase in different degrees only from the perspective of heat resource. The stable- yield northern limits of rainfed winter wheat-summer maize rotation moved southeastward in most regions, which was caused by the decrease of local precipitation in recent years. During the past 50 yr, climate warming made the national northern limits of cropping systems move northward in different degrees, the northern limits of winter wheat and double rice both moved northward, and the cropping system change would cause the increase of per unit area grain yield in the change region. However, the stable-yield northern limits of rainfed winter wheat-summer maize rotation moved southeastward due to the decrease of precipitation.

The Effect of Organo-Mineral Fertilizer Applications on the Yield of Winter Wheat, Spring Barley, Forage Maize and Grass Cut for Silage

Biosolids were applied with urea to produce a granulated organo-mineral fertiliser (OMF) for application by farm fertiliser equipment to a range of agricultural crops. The recommended rates of nitrogen, phosphate and potash were calculated for the test crops using “The Fertiliser Manual”, which assesses the nutrient requirement based on previous cropping, rainfall and soil index. The OMF produced similar crop yields compared to ammonium nitrate fertiliser when applied as a top-dressing to winter wheat, forage maize and grass cut for silage in the cropping years 2010 to 2014. In 2012 the grain yield of spring barley top-dressed with OMF was significantly lower than the conventional fertiliser treatment, due to dry conditions following application. For this reason it is recommended that OMF is incorporated into the seedbed for spring sown crops and The Safe Sludge Matrix guidelines followed. The experimental work presented shows that OMF can be used in sustainable crop production systems as a source of nitrogen and phosphorus for a range of agricultural crops.

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.

Study on the Effects of Extreme Precipitation for Seven Growth Stages of Winter Wheat in Northern Weihe Loess Plateau, China

The research on the characteristic frequency of precipitation is a great significance for guiding regional agricultural planning, water conservancy project designs, and drought and flood control. Droughts and floods occurred in northern Weihe Loess Plateau, affecting growing and yield of winter wheat in the area. Based on the daily precipitation data of 29 meteorological stations from 1981 to 2012, this study is to address the analysis of three different frequencies of annual precipitation at 5%, 50%, and 95%, and to determine the amount of rainfall excess and water shortage during seven growth stages of winter wheat at 5%, 10%, and 20% frequencies, respectively. Pearson type III curve was selected for this study to analyze the distribution frequency of annual rainfall and rainfall amount following seven growth stages of winter wheat crop in 29 stations of Northern Weihe loess plateau. As a result of our study, annual precipitation is gradually increasing from southwest to northeast of Northern Weihe loess plateau. The highest amount of annual precipitation occurred in the Baoji area and the lowest precipitation covered by the northwest area of Northern Weihe loess plateau. Moreover, the amount of rainfall of seven growth stages indicates that excessive rainfall occurs not only in the first stage (sowing to tillering) and seventh stage (flowering to ripening) but also in second stage (tillering to wintering). In the seventh stage, a large amount of excessive rainfall occurred in Changwu, Bin, Qianyang, Fengxiang, Baojiqu, and Baojixian. Moreover, water shortage is distributed in the third stage (from wintering to greening), the fourth stage (from greening to jointing), the fifth stage (from jointing to heading), and the sixth stage (from heading to flowering). Furthermore, the worst water shortages occurred in Hancheng, Heyang, Chengcheng, Pucheng, Dali, Tongchuan, and Fuping in the fourth stage (greening to jointing stage). Even though we study the crop water requirement under extreme rainfall conditions, the amount of rainwater still supply inadequate in some parts of the winter wheat growth stage. Therefore, this study provides main clues for the next step to study the irrigation water needs of winter wheat crops and to reduce agricultural risks in 29 counties in the northern loess plateau and other regions.

“油-稻-稻”三熟制早熟冬油菜氮高效基因型及鉴定指标筛选

【目的】旨在筛选适宜“油-稻-稻”三熟制的氮高效早熟冬油菜基因型及其简易筛选指标。【方法】利用田间小区试验,选用了生育期185 d以下的的适宜“油-稻-稻”三熟制种植的14种早熟冬油菜基因型,进行正常施氮(N_(1))和不施氮(N_(0))处理。根据不同冬油菜基因型氮肥利用率(NUE)的差异,利用树状聚类分析进行分类,形成高、中、低3种氮效率基因型。同时通过逆向溯源的方法,观察分析3种氮效率基因型在不同氮水平条件下的产量构成、主要农艺性状、干物质积累及氮素吸收等方面的表现特征。总结分析出氮高效冬油菜基因型的一些简易判断的指标。【结果】不同氮效率基因型冬油菜在产量形成、主要农艺性状等方面存在显著差异。N1处理下成熟期早熟冬油菜的主要农艺性状的表型值和变异系数基本表现大于N0处理。因此,以N1处理下不同基因型的农艺性状表现作为不同氮效率基因型的鉴别标准。N1处理下,氮高效基因型比氮中效和氮低效基因型产量高、单株角果数多、每角粒数多、株高高、主花序长、一级分枝数多、角果密度高、各部位干物质积累量高、籽粒中氮含量高、氮肥偏生产力、氮肥农学效率、氮肥生理利用率和氮收获指数均较高。【结论】沣油737是适合南方“油-稻-稻”三熟制的氮高效早熟冬油菜;正常施氮条件下,成熟期较多的单株角果数与每角粒数,以及较高株高是判断早熟冬油菜氮高效基因型的简易指标。

江苏省冬小麦需水量时空变化特征及气候影响因素分析

为实现江苏省冬小麦科学灌溉、提高农业用水效率,明晰江苏省冬小麦需水量及气候影响因素的时空变化特征,为全省冬小麦灌溉管理及农业水资源高效利用提供科技支撑,基于江苏省共计12个地区2013-2022年冬小麦季相关气象资料,通过Penman-Montieth法计算近十年来江苏省冬小麦需水量,并利用Pearson相关分析法对近十年江苏省冬小麦需水量时空变化特征、需水特性以及气象影响因素进行了分析。近十年间江苏省年平均气温、日平均湿度、地表温度、降水量、蒸发量、平均日照时数均呈总体上升趋势,太阳总辐射量呈减小趋势。近十年来江苏省冬小麦本田期的需水量平均值为451.82~692.50 mm,年际变化范围在540.19~646.70 mm,不同年份间呈现减小的趋势,空间上则呈现由西北向东南递减的趋势。江苏省大部分地区冬小麦需水强度最小值出现在1月,5-6月抽穗期与灌浆期需水强度最大。江苏省冬小麦全生育期需水量与年均降雨量、日均湿度之间存在负相关关系,与年均水面蒸发量、年均日照时数、年平均气温间存在正相关关系,这其中以日均湿度、年均水面蒸发量、年均气温对冬小麦需水量的影响最为明显。并且,近十年冬小麦全生育期需水量的总体下降趋势可能是由于其与日均湿度明显更高的负相关性所导致。总之,近十年来江苏省冬小麦需水量逐年有下降趋势,且由西北向东南递减,此外全省日均湿度、年均水面蒸发量、年均气温是近年来冬小麦需水量变化的主要影响因素。

豫北两熟区不同夏播作物对后茬冬小麦中后期群体微环境及产量的影响

为探讨不同夏播作物前茬对后茬冬小麦生长和产量的影响,在河南省新乡市获嘉县开展田间二因素试验,设置两个不同施肥水平(常规施肥和不施氮肥)和三种夏播作物前茬(玉米、大豆和花生),分析小麦拔节期至成熟期叶面积指数(LAI)、叶夹角(LA)、光合有效辐射(PAR)、叶片叶绿素含量(SPAD)、叶绿素荧光(F_(v)/F_(m)),以及土壤含水量(SWC)、土壤温度(Ts)和土壤呼吸速率(Rs)变化,并在成熟期测定小麦产量及其构成因素。结果表明,与常规施肥(CK)相比,不施氮肥条件下不同前茬的小麦LA略增,而LAI、IPAR、SPAD、F_(v)/F_(m)、SWC、Ts和Rs均有所降低。不施氮肥条件下,花生前茬的小麦LAI、IPAR、SPAD、F_(v)/F_(m)、SWC、Ts和Rs均显著低于其他两种前茬(P<0.05),其中花生、大豆和玉米前茬的SWC较CK的降幅分别为13.56%、13.39%和10.77%。与CK相比,不施氮肥条件下,花生前茬的小麦LA较CK的增幅在3种前茬中居中,小麦株型较为紧凑,有利于改善植株下层光合辐射,为群体生长创造良好的光合和土壤条件,其产量较玉米和大豆前茬分别高20.0%和21.9%;玉米前茬的整体表现不如大豆和花生前茬,但其和花生前茬的小麦千粒重和群体数均较高,因而产量居中;大豆前茬的小麦结实小穗数和干物质量较高,但其小麦千粒重较低,最终籽粒产量也较低。综合来看,在两熟种植模式中,选用花生作为冬小麦的前茬作物是豫北地区一年两熟区作物配置的一种较优选择。

湖北省小麦潜在产量时空异质性特征及驱动因子分析

气候变化致使气象要素的时空分布格局发生了不同程度的变化,加剧了作物产量空间异质性的形成。因此,评估气候因子对潜在产量的贡献程度,有利于解析区域间潜在产量差异的形成机制,这对于区域内作物的合理规划和缩小区域间产量差具有重要意义。本研究基于1985—2021年湖北省小麦生长期间的气候数据,应用验证后的APSIM-Wheat模型模拟小麦的潜在产量,利用多元回归等方法评估各气候因子对潜在产量变化的贡献程度,解析潜在产量空间异质性的形成机制。结果表明:湖北省小麦潜在产量变化范围为5068.9~7895.3 kg∙hm^(−2),平均潜在产量为7187.6 kg∙hm^(−2)。近35年来,小麦生育期内的平均温度和总降水量分别以0.1℃∙(10a)−1和13.2 mm∙(10a)−1的速率增加,但总太阳辐射以123.3 MJ∙m^(−2)∙(10a)^(−1)的速率下降。这些气候因素变化加剧了生育期内易涝、弱光环境的形成,导致小麦生产潜力降低,潜在产量平均每10年下降422.0 kg∙hm^(−2),降水量的增加对潜在产量下降的贡献最大,相关系数高达−0.73。湖北省小麦潜在产量的空间分布特征为北高南低,南北小麦平均潜在产量和光热熵差距分别为218 kg∙hm^(−2)和0.06 MJ∙m^(−2)∙d^(−1)∙℃^(−1)。光热熵的高度空间异质性是造成潜在产量差异的主要因素,二者相关性高达0.82。受光热熵时空分布不均的影响,荆州小麦拔节至成熟期的平均每日生长速率较襄阳地区低28.5 kg∙hm^(−2)∙d^(−1),最终导致荆州小麦的潜在产量较襄阳地区低。综上,气候变化使得湖北省小麦潜在产量整体呈下降趋势,针对以江汉平原地区为代表的易涝、弱光的小麦生长环境,选育具有高光效和耐涝性的小麦品种对于缩小区域间的产量差距和实现区域粮食总产的全面提高具有重要意义。

覆土种植杏鲍菇营养评价与效益分析

以工厂化种植杏鲍菇为对照,检测覆土种植不同采收期杏鲍菇的蛋白质、氨基酸、脂肪等营养成分和种植前后土壤养分含量,根据覆土种植投入产出计算效益,探讨冬闲田杏鲍菇覆土种植-菌渣还田-粮食/水果/蔬菜轮作种植模式的可行性。结果表明,不同采收期覆土种植杏鲍菇鲜品子实体蛋白质、脂肪、氨基酸等含量均高于工厂化种植,采收期对覆土种植杏鲍菇蛋白质含量影响较大,成熟初期含量最高,达4.19 g/100 g,是成熟期的1.3倍、孢子释放期的1.6倍、工厂化种植的1.9倍。覆土种植杏鲍菇必需氨基酸、呈味氨基酸含量均高于工厂化种植,E/T值接近FAO/WHO提出的优质蛋白质氨基酸组成值。菌渣还田后土壤有机质含量提高了116%,杏鲍菇从覆土到采收完毕共34 d,生物转化率可达136%,投入产出比达1:1.8。冬闲田覆土种植杏鲍菇子实体营养丰富,味道鲜美,经济效益好,菌渣还田可提高土壤有机质含量,适合在南方水稻主产区、荔枝等果园的林下冬春季推广应用。

日光温室秋冬茬番茄东西垄宜机化栽培适宜垄距参数研究

为了促进日光温室蔬菜机械化生产,探求适宜日光温室番茄东西垄宜机化栽培的垄距参数,以番茄品种瑞一郎为试验材料,以传统南北垄栽培方式为CK,设置RD1(中心垄距1.6 m)、RD2(中心垄距1.8 m)、RD3(中心垄距2.0 m)东西垄3个处理,研究东西垄不同垄距处理对日光温室番茄植株冠层环境、生长、产量及果实品质的影响。结果表明:与CK相比,东西垄3种垄距处理番茄株高、茎粗、茎叶鲜质量、果实品质等无显著差异;RD2处理单株光截获量、单株产量分别比CK增加11.22%和11.17%,差异均达到显著水平。在RD2条件下,与CK相应位置比较,东西垄南侧行单株光截获量普遍高于北侧行,并高于CK,同时东西垄南侧行平均单株产量提升6.30%~21.46%、北侧行平均单株产量提升4.06%~10.93%。此外,RD2垄间(作业道)宽1 m能够满足宽度为50~75 cm的多功能作业平台车作业需求。综上,中心垄距1.8 m是适宜日光温室番茄东西垄宜机化栽培的垄距参数。