麦桐作田内小麦产量评价初探

运用方差分析、模糊聚类、判别分析等方法,对麦桐间作田内受树龄、行距、距树距离影响的小麦产量分布状况作了初步分析,找出了使二者均能获得较好的经济效益的间作组合方式,即初期泡桐行距为20m,当泡桐长至4年时,隔行砍伐,使行距变为40m.     

用模糊聚类法预报冬小麦产量趋势

利用长安气象观测站10a的冬小麦生育期、产量及气象观测资料，用回归分析确定出冬小麦生育期的冬前分蘖、拔节到孕穗期降水量、开花到乳熟期的降雨日数3个因子与冬小麦产量相关显。然后利用这3个因子进行模糊聚类，并用预报年的相关资料计算做出产量趋势预报。对1999年2000年西安地区产量年景试报，预报结果正确。     

哲盟气候条件对小麦产量的影响及其动态评价

文章以积分回归方法统计分析了旬平均气温、日照、降水量与哲盟小麦产量的关系，得到了较为满意的结论，并以上述关系为依据，根据所在年小麦生育期间的逐旬气象条件，对小麦生育状况进行定量动态评价，服务效益亦较为明显。因此认为该方法是有实用价值的。     

豫南稻区小麦产量及其构成因素的气候生态评价

从农业气候生态角度分析了影响豫南稻区小麦产量及其构成因素的气候因子，结果表明，对豫南稻区小麦生产影响最大的气候因子是涝灾。由于降水冬前比冬后变化大，常出现生育前期旱涝和中后期湿害。因此，建议在选用小麦品种时，一要注重早熟性，二要注意产量三要素协调、丰产性好，三要有配套的耕作栽培技术。     

豫南稻区小麦产量及其构成因素的气候生态评价

从农业气候生态角度分析了影响豫南稻区小麦产量及其构成因素的气候因子,结果表明,对豫南稻区小麦生产影响最大的气候因子是涝灾。由于降水冬前比冬后变化大,常出现生育前期旱涝和中后期湿害。因此,建议在选用小麦品种时,一要注重早熟性,二要注意产量三要素协调、丰产性好,三要有配套的耕作栽培技术。     

Quantitative evaluation of climatic variability and risks for wheat yield in India

This study comprises (1) an analysis of recent climate trends at two sites in north-west India (Ludhiana in Punjab and Delhi) and (2) an impact and risk assessment for wheat yields associated with climatic variability. North-west Indian agriculture is dominated by rice-wheat rotation in which the wheat season (‘rabi’, November to March) is characterized by predominantly dry conditions—superimposed by very high inter-annual variability of rainfall (17 to 260 mm in Ludhiana and <1 to 155 mm in Delhi). While rainfall remained without discernable trend over the last three decades, minimum and average temperatures showed increasing trends of 0.06 and 0.03°C year^???1, respectively, at Ludhiana. The site in (metropolitan) Delhi was apparently influenced by city-effects, which was noticeable from the decrease in solar radiation of 0.09 MJ m^???2 day^???1 year^???1. The CERES-wheat model was used to calculate yields of rainfed wheat that were at both locations highly correlated with seasonal rainfall. An assessment framework was developed to quantify yield impacts due to rainfall variability in three steps: (1) data from different years were aggregated into four classes, i.e., years with scarce, low, moderate, and high rainfall, (2) yield records of each rainfall class were ranked according to yield to facilitate (3) a comparison of yields with identical rank, i.e. among the best yield of each class, the second-best, etc. The class with moderate rainfall was taken as baseline yield to compute yield impacts of other rainfall scenarios. Years with scarce rainfall resulted in only 34% (Ludhiana) and 35% (Delhi) of the baseline yield. The yields in years with low rainfall accounted for 61% (Delhi) and 49% (Ludhiana) of the baseline yields. In Ludhiana, high rainfall years resulted in 200% yield as compared to the baseline yield, whereas they reached only 105% in Delhi. Low-intensity (1× and 3×) irrigation decreased the relative yield losses, but entailed a higher vulnerability in terms of absolute yield losses. Only high-intensity (4×) irrigation buffered wheat yields against adverse rainfall years. Early sowing was beneficial for wheat yields under all rainfall scenarios. The framework could be a valuable decision-support tool at the farm level where seasonal rainfall variability is high.     

镇江市小麦产量预报方法的研究——Baier-Robertson模型的一种改进型

本文根据作物产量形成与农艺性状的关系,构造了作物气候参量,籍此对Baier-Robertson模型作了改进。兼顾因子的显著性、稳定性和独立性,建立了镇江市小麦产量预报模式并作了试报。     

Atmospheric pressure and wheat yield modeling

Principal components of monthly sea level pressure representing large scale general circulation features such as persistent upper level troughs and ridges, blocking highs, semipermanent pressure cells, standing eddies, etc., are the predictors in a linear regression on yield for large wheat production regions in the United States, Canada, and the Soviet Union. The purpose of this modeling is to estimate national level of production and to demonstrate a link between crop forecasting and extended atmospheric outlooks. Long term, reliable records of pressure data are used. The models also benefit from the quality, reliability, and availability of foreign crop data for large areas. The monthly pressure field exhibits significant spatial collinearity which determines the time orthogonal principal components. The use of these principal components in the regression leads to a fewer number of required predictors, more stable signs on regression coefficients, minimal variance inflation of regression coefficients, and the ability to objectively partition the principal components into “real” and “noise” relationships to yield. Correlation fields are determined by correlation of pressure data to area weighted temperature or precipitation. These are used to evaluate the physical interpretation of space orthogonal eigenvector fields. The correlation fields and eigenvectors are used together to ensure that the signs on regression coefficients for principal components in the final yield equation make agronomic sense. The statistical structure of the models is discussed. Generally, the models have an explained variance of approximately 0.90 and a standard error of 1.5 quintals per hectare. For 1975 and 1976 these wheat yield models provided operational estimates which are generally within two quintals per hectare of official estimates.     

土壤水分条件对冬小麦生长发育及产量构成影响研究

通过2011-2013年中国气象局固城生态环境与农业气象试验站冬小麦种植试验,利用冬小麦不同生育期土壤湿度、根长密度、株高、绿叶面积和产量等资料,研究不同土壤水分条件对河北固城冬小麦生长发育和产量构成的影响。结果表明：2011-2012年固城站冬小麦0-50 cm土壤相对湿度>50%为冬小麦适宜土壤湿度。2012-2013年固城站冬小麦各生育期0-80 cm土壤相对湿度<55%时,尽管80-120 cm土壤相对湿度为55%-80%,但冬小麦根系和产量构成要素均较小。冬小麦各生育期0-80 cm土壤相对湿度为55%-70%时,冬小麦根系总量最多,则冬小麦生长发育最好,产量构成要素均较好,总产量最高。冬小麦各生育期0-120 cm土壤相对湿度<55%时,冬小麦根系总量最小,且根系集中分布的深度也较浅,总产量最小。冬小麦各生育期0-120 cm土壤相对湿度>80%时,冬小麦根系总量较多,但总体产量比0-80 cm土壤相对湿度为55%-70%时低。     

四川省小麦产量的自然正交分解模型

利用四川省小麦历年产量重构二维时变矩阵,进行自然正交展开后得到了三种产量分解模型.在每种模型中,可将小麦产量分解成了三个产量分量之和,即小麦产量Y＝Y1+Y 2+Y3.这些产量分量不仅反映了生产力水平增长对产量趋势的作用,也反映了气候环境因子波动对产量年际变化的综合影响.该方法与传统的产量分解模型相比,具有计算简单客观、各种分量同时一次分离和分量之间相互独立的特点,为农作物产量分解和预报提供了一种新的思路.     

Effects of diurnal temperature range and drought on wheat yield in Spain

This study aims to provide new insight on the wheat yield historical response to climate processes throughout Spain by using statistical methods. Our data includes observed wheat yield, pseudo-observations E-OBS for the period 1979 to 2014, and outputs of general circulation models in phase 5 of the Coupled Models Inter-comparison Project (CMIP5) for the period 1901 to 2099. In investigating the relationship between climate and wheat variability, we have applied the approach known as the partial least-square regression, which captures the relevant climate drivers accounting for variations in wheat yield. We found that drought occurring in autumn and spring and the diurnal range of temperature experienced during the winter are major processes to characterize the wheat yield variability in Spain. These observable climate processes are used for an empirical model that is utilized in assessing the wheat yield trends in Spain under different climate conditions. To isolate the trend within the wheat time series, we implemented the adaptive approach known as Ensemble Empirical Mode Decomposition. Wheat yields in the twenty-first century are experiencing a downward trend that we claim is a consequence of widespread drought over the Iberian Peninsula and an increase in the diurnal range of temperature. These results are important to inform about the wheat vulnerability in this region to coming changes and to develop adaptation strategies.

     

Growth and yield of rainfed wheat on the seasonally dry Aegean Islands

Summary The effects of water regime on the rate of growth, the growing period and the yield of a winter wheat crop in the summer-dry climate of Aegean Islands are examined. It is shown that wheat growing period is significantly restricted by either, unfavourable weather conditions at planting (coinciding with the start of rains), or by early soil moisture depletion at the end of the wet season. The probability of a successful early planting, which is conditional on a considerable pre-planting rainfall not being following by a long (10-day) dry spell, is estimated by recurrence relationships. Farmers on the driest (south) islands will have a 25% risk for unsuccessful planting before November 14. Evapotranspiration rates, estimated by the Penman-Monteith equation, are optimum for crop growth for about two months after wintering. The growing season on average comes to an end by the end of spring (soon after anthesis), when the available soil moisture. (estimated by a simple water balance equation) drops to zero.The water shortage, especially during the grains-filling period, may reduce yields by up to 75%, depending on the length and severity of the soil moisture deficit at the site. Reliability and distribution of rainfall suggest that the risks of water deficits in rainfed cropping vary across the region. In order to minimise yield losses from crop failures, farmers should adjust areas sown each year according to the date when the wet season starts.With 10 Figures     

阶段性干旱胁迫对小麦光合生理特性及产量结构的影响

在人工遮雨的条件下,采用盆栽的种植方式探究"皖麦68"营养生长期(返青期—开花期)及生殖生长期(开花期—成熟期)轻度干旱胁迫(土壤相对含水量为55%±5%)及复水(土壤相对含水量为70%±5%)对其光合生理特性及产量结构的影响。结果表明:返青期至成熟期充分供水(CK)的小麦旗叶光合参数和产量最高。开花至成熟期复水(DN)的小麦叶片在复水后光合能力迅速恢复,表现出了超补偿效应:光合速率(16.43μmol/(m~2·s))甚至超过了CK(15.01μmol/(m~2·s));采用非直角双曲线模型拟合小麦旗叶的光响应曲线,其中DN的曲角θ最大;DN产量较CK略有降低但千粒重为34.51 g,高于CK(34.44 g)。开花至成熟期轻度干旱(ND)及全生育期轻度干旱(DD)的小麦光合特征参数与产量均显著降低。DD产量最低、品质最差,但其收获指数I_H高于CK、仅次于DN。在小麦返青期—开花期进行水分管理适量减少灌溉,开花期—成熟期复水能够提升籽粒的干物质积累量,获得较高的产量及品质。