Crop Growth, Disease and Yield Components of Rusted Phaseolus Beans in Ethiopia

Crop growth and disease epidemics in sprayed and non-sprayed bean plots, artificially infected with rust (Uromyces appendiculatus) 3 weeks after emergence. were assessed weekly in two cultivars, at two locations for two seasons. Disease intensity was regulated by the application of a fungicide at 5 spray frequencies. Fungicide application influenced leaf area index (LAI) and reduced rust intensity. The fungicide had no significant effect on other diseases and dead leaf area. Fungicide application increased seed yield (SY) by increased numbers of pods per plant (PP). Rust severity was strongly correlated with pustule density but the overall relationships among rust assessment parameters depended on cultivar and location. Seed yield and pods per plant were highly correlated with LAI. The relationships between LAI and seeds per pod or seed weight depended on cultivar and location. Overall rust assessment parameters (rust severity and pustule density) showed close, negative relationships with seed yield. seed weight and pods per plant but not with seeds per pod. The relationships obtained in the partially resistant line 6-R-395 were less definite than those in the susceptible line Mexican 142. The yield parameters seed yield and pods per plant, showed strong positive relationships.     

Estimates of broad-sense heritability for seed yield and yield criteria in faba bean (Vicia faba L.)

Eight faba bean (Vicia faba L.) genotypes were grown at lowlands of the west-Mediterranean region of Turkey in order to estimate the broad-sense heritability for plant height, number of stems and pods per plant, seed yield, biological yield, 100-seed weight, days to flowering and maturity. The heritability for plant height, number of stems and pods per plant, seed yield, biological yield, 100-seed weight, days to flowering and maturity were estimated as 83%, 63%, 43%, 62%, 52%, 99%, 97% and 97%, respectively. It was found that seed weight was the least affected trait across changing environmental conditions and followed by days to flowering and maturity. On the other hand, number of pods per plant, biological and seed yields and number of stems per plant were the most affected traits versus environmental conditions.     

Interactions between a seed-borne strain of cucumber mosaic cucumovirus and its lupin host

The relationship between time of inoculation with cucumber mosaic cucumovirus (CMV) and the growth, seed production and rate of seed transmission of virus in lupin (Lupinus angustifolius cv. Illyarrie) was studied in field-grown plants. Plants inoculated at the seedling stage (2 days post-emergence) showed 45% mortality. Plants infected through the seed were more stunted than plants inoculated at the seedling stage. Plants inoculated up to the mid-vegetative growth stage (58 days post-emergence) yielded ≤ 27% of the dry matter and ≤ 9% of the seed of healthy plants. Late inoculation (114 days post-emergence) did not affect dry matter yield, but reduced seed yield to 75% of that of healthy plants. Rate of seed transmission depended on the time of inoculation of plants. The maximum rate was 24.5% for plants that were inoculated at the mid-vegetative growth stage (58 days post-emergence). However, early inoculation caused a large reduction in seed yield, and it was shown that plants inoculated at the beginning of flowering (94 days post-emergence) produced greater numbers of infected progeny than plants inoculated at earlier or later times. No relationship was observed between seed weight and transmission of CMV. Infectious CMV was recovered from the embryo, but not from the testa. A simple seed transmission model was used to evaluate several hypothetical epidemics and to determine the time of inoculation which results in greatest rates of seed transmission of CMV. For example, when fewer than 73% of plants in a crop become infected with CMV, then the rate of transmission of virus in crop seeds will be greatest when inoculations are at the beginning of flowering.     

Evaluation of an organic treatment for post-harvest control of crown rot of banana

An organic treatment for control of crown rot disease of banana was developed and evaluated at EARTH University in Costa Rica. Studies were conducted to evaluate the efficacy of Biocto 6 (seed extract from citrus) in combination with the wax-based adjuvant Verdiol for control of post-harvest crown rot of banana. The standard commercial fungicide treatment (thiabendazol, imazalil and ammonium sulfate) and an untreated control were included for comparison. Bananas with the various treatments were processed using standard commercial procedures and stored in a refrigerated chamber that was modified to simulate commercial transport, distribution and controlled ripening for exported bananas. Fruit clusters were evaluated for percent weight loss, ripening in storage and crown rot disease severity. At the end of the 28-day storage period, there were no significant differences in percent weight loss between any of the treatments. There was no significant difference in ripening (maturity level) between the organic treatment and the commercial fungicide standard in 2 years of testing. In 2003, the untreated control had a significantly higher maturity rating than the organic or standard fungicide treatment. However, there were no significant differences in any of the treatments in maturity level in 2005. There was no significant difference between the organic and standard fungicide treatment for crown rot control and both treatments had significantly less crown rot than the untreated control. Results indicate that Biocto 6 in combination with Verdiol wax provides a new organic alternative for control of post-harvest crown rot of banana.     

Effects of previous cropping and fungicide timing on the development of light leaf spot (Pyrenopeziza brassicae), seed yield and quality of winter oilseed rape (Brassica napus)

Light leaf spot, caused by Pyrenopeziza brassicae, was assessed regularly on double-low cultivars of winter oilseed rape during field experiments at Rothamsted in 1990-91 and 1991-92. Previous cropping and fungicide applications differed; seed yield and seed quality were measured at harvest. In each season, both the initial incidence of light leaf spot and the rate of disease increase were greater in oilseed rape crops sown after rape than those sown after cereals. The incidence of diseases caused by Phoma lingam or Alternaria spp. was also greater in second oilseed rape crops. In 1991-92 there was 42% less rainfall between September and March than in 1990-91, and much less light leaf spot developed. However, P. lingam and Alternaria spp. were more common. Only fungicide application schedules including an autumn spray decreased the incidence of light leaf spot on leaves, stems and pods, as indicated by decreased areas under the disease progress curves (AUDPC) and slower rates of disease increase. Summer sprays decreased incidence and severity of light leaf spot on pods only. In 1990-91, all fungicide treatments which included an autumn spray increased seed and oil yields of cv. Capricorn but only the treatment which included autumn, spring and summer sprays increased yields of cv. Falcon. No treatment increased the yields of cv. Capricorn or cv. Falcon in 1991-92. Fungicide applications decreased glucosinolate concentrations in the seed from a crop of cv. Cobra severely infected by P. brassicae in 1990-91, but did not increase yield.     

The potential of lentil (Lens culinaris) as a grain legume crop in the UK: an assessment based on a crop growth model

A crop growth model developed in Canterbury, New Zealand was used to assess the potential of lentil (Lens culinaris) as a grain legume crop in the UK. The model was validated using five sowing dates at Durham (54.77°N, 1.58°W) in 1999. Predicted time to flowering was within 7 days of actual time to flowering and predicted seed yields were within 9% of actual yields. Actual yields ranged from 1.40 to 1.65 t ha‐¹. Seed was of high quality. The model was used to predict rate of development and yields of spring and autumn sown lentils at eight sites along a transect from NW Scotland (Stornoway, 58.22°N, 6.32°W) to SE England (East Mailing, 51.28°N, 0.45°E) chosen to encompass important environmental gradients in the UK. In general, for a 1 May sowing with 150 or 250 mm plant available water (PAW) and a 1 October sowing with 150 mm PAW, predicted mean values over the period 1987–95 for maximum crop growth rate, maximum leaf area index, radiation intercepted, total dry matter produced and seed yield were closely positively related to monthly mean values for mean daily air temperature and increased along the transect from NW to SE UK. Time to flowering generally decreased along the transect from NW to SE UK ranging from 28 June to 9 July and from 20 May to 14 June with the May and October sowings respectively. For the 1 May sowing with 250 mm PAW, predicted mean seed yield ranged from 1.00 to 1.90 t ha‐1. For all sites, yield was very stable over the 9 yr period. For the 1 May sowing with 150 mm PAW, predicted mean seed yield ranged from 0.97–1.23 t ha‐1. Yields for the four more southerly sites were more variable at the lower PAW and, in exceptionally dry years, were substantially lower than average. For these sites, autumn sowing increased seed yields in exceptionally dry years and gave similar or greater mean seed yields to spring sowing with 250 mm PAW. For East Mailing, predicted yields for autumn sowing were on average 2.78 t ha‐1. Also, for Stornoway, because of its relatively high overwinter temperatures, the model predicted substantial increases in yield with autumn sowing. It is concluded that lentil has considerable potential as a grain legume crop in the UK.     

The influence of pre-floral growth and development on the pathway of floral development, dry matter distribution and seed yield in oilseed rape (Brassica napus L.)

Patterns of floral development, dry matter distribution and seed yield were examined in winter oilseed rape plants subjected to different pre-floral growth environments. The duration of pre-floral growth and plant size at flower initiation, measured in terms of total mainstem leaf number, were manipulated by varying the temperature between seedling emergence and flower initiation. Exposure of seedlings to low temperatures from cotyledon expansion onwards markedly reduced the duration of pre-floral growth and the number of leaves on the mainstem. The subsequent development pattern of plants was largely dependent on the date of flower initiation and therefore vernalisation requirement. Indeed, the period of growth from flower initiation to maturity, considered on the basis of thermal time, was directly related to the duration of pre-floral growth and mainstem leaf number. The thermal durations of the bud development phase and flowering period in plants exposed to different pre-floral cold treatments but with a common date of flower initiation were similarly linked to these two parameters. Plants exposed to prolonged periods of low temperature treatment from cotyledon expansion onwards initiated fewer mainstem leaves during a relatively short pre-floral growth phase and their yield potential was limited by a reduction in branch and flower numbers. Plants maintained at higher temperatures produced more mainstem leaves during an extended period of pre-floral growth and supported a greater number of branches and flowers. However, this additional yield potential was not realised due to a reduction in seed numbers and mean seed weight. It appeared that seed yield of these plants was limited by increased competition between an excessive number of lower branches and flowers, a problem apparently created by excessive pre-floral growth. Minimal competition for available assimilates between the limited number of branches of plants with a shorter pre-floral growth phase and fewer mainstem leaves, resulted in lower levels of pod abortion, greater seed production and ultimately increased seed yields.     

Growth and development of soyabean cv. TK5 as affected by tropical daylengths, day/night temperatures and nitrogen nutrition

Two experiments were done in Saxcil growth cabinets in order to investigate the effects of climatic factors and nitrogen nutrition on the growth, reproductive development and seed yield of soyabean cv. TK5. In the first, plants were grown to maturity in eight environments comprising all combinations of two short daylengths (11 h 40 min and 13 h 20 min), two day (27 and 33^oC) and two night (19 and 24^oC) temperatures. In the second, day temperature was kept at 33^oC but the night temperature was varied (19 and 24^oC) as was the mineral nitrogen supply (20 and 197 ppm N) to plants which were either inoculated or not with an effective single strain of Rhizobium. Taller, more branched, later flowering plants were produced in the longer daylength but seed yield was hardly affected because the components of yield did not all respond similarly. In the higher day temperature treatments seed yield per plant was reduced by half because all yield components were adversely affected - pods per plant by 34 %, mean seed dry weight by 24 % and seeds per pod just slightly. There was a marked effect of the higher night temperature which promoted early vegetative growth, induced early flowering and although the number of pods per plant was, overall, reduced by 48 %, seed yield per plant was little affected as mean seed dry weight was increased by 37 % and the number of seeds per pod was also increased slightly. Prior to flowering, nodulated plants obtained about two thirds of their total nitrogen requirement via direct uptake and one third through the symbiotic system. Vegetative dry weight and plant nitrogen content were increased by the higher mineral nitrogen level and, although height was slightly diminished, more branches were produced. Seed yield, however, was only slightly increased. These experiments have shown that night temperature is an environmental factor of major importance for the growth of this soyabean cultivar. They have provided, also, a more rational basis for interpreting seasonal variations in growth and seed yield of soyabean in the tropics where, clearly, day and night temperature effects can override those of daylength and nitrogen nutrition.     

Effects of foliar application of 6-benzylaminopurine on yield and oil content in two spring safflower (Carthamus tinctorius L.) cultivars

To study the effect of an exogenous cytokinin application on safflower yield, an experiment was conducted in 2012–2013. Two cultivars of safflower (Goldasht and Zendehrood) and five concentrations of 6-benzylaminopurine (BAP) (0, 25, 50, 75, and 100 μM) were applied at the flowering stage. Results indicated that the application of 75 μM of BAP showed increased seed and oil yield by 17.54 and 18.29 % over the control, respectively. The increase in seed yield by application of BAP was attributed to the increase in characters like number of heads per plant, number of seeds per head, and 1,000 seed weight. Applying of BAP increased oil content compared with the control. To determine the concentration of cytokinin which has the highest performance for increasing seed yield, regression analysis were estimated showing that in the Zendehrood cultivar, the application of 43 μM of BAP produced the highest seed yield, and in the Goldasht cultivar the application of 73 μM of BAP during flowering produced the highest seed yield.     

Proteins of Soybean Seeds: II. Accumulation of the Major Protein Components during Seed Development and Maturation

Fresh weight and dry weight as well as quantitative and qualitative protein changes in the developing soybean (Glycine max) seed were described from 12 days after flowering until maturity. The seed proteins were separated on sucrose density gradients into three major fractions, having average sedimentation coefficients of 2.2S, 7.5S, and 11.8S. The 2.2S sedimenting proteins predominated at very early stages of development (12 days after flowering) and decreased proportionately throughout maturation. The 7.5S and 11.8S components appeared to be synthesized later in maturity and in larger amounts than the 2.2S proteins. Electrophoretic studies on extracts from whole seeds and on isolated protein fractions confirmed the early abundance of proteins in the 2.2S fraction and revealed temporal differences in the accumulation of three components of the 7.5S fraction. The 11.8S sedimenting fraction appeared throughout seed development as a homogeneous protein which accumulated in the seed with a time course similar to that of the total 7.5S protein fraction.     

Effects of daylength and day/night temperatures on growth and seed yield of cowpea cv. K 2809 grown in controlled environments

The effects of climatic factors on the growth, reproductive development and seed yield of cowpea (cv. K 2809) were investigated in controlled environment cabinets. Plants were grown to maturity in eight environments comprising all combinations of two day lengths (11 h 40 min and 13 h 20 min), two day (27 and 33 ^oC) and two night (19 and 24 ^oC) temperatures. The plants were nodulated (Rhizobium strain CB 756) and received 197 ppm N throughout growth. Treatments changed the time to the appearance of first flowers by a maximum of 6 days but the later-flowering plants more than doubled their dry weight during this period, so that effects on plant form and, ultimately, seed production were considerable. Warm nights (24 ^oC) not only hastened the onset of flowering but also enhanced dry matter production during the pre-flowering period; they did not extend the total growing period. Warm days (33 ^oC) did not enhance dry matter production but shortened the duration of the growing period by an average of 21 days (20%). Variation in final seed yield was mainly due to differences in the number of pods borne on branches. Warm days markedly decreased the number of pods per plant (an overall average reduction of 49%) as did warm nights in conjunction with the long (13 h 20) daylength. The number of seeds per pod was effected only by daylength (8.3 and 7.6 seeds in the long and short daylengths, respectively). Mean seed weight was decreased by 19% in warm as compared to cool nights but was increased by 18% in warm as compared to cool days. These responses are compared with those obtained with soyabean cv. TK5 in a previous experiment and are shown, in general, to be similar.     

Autumn sowing increases severity of pasmo (Mycosphaerella linicola) on linseed in the UK

Surveys and field experiments showed pasmo to be the most serious disease affecting UK winter linseed in the 1997–98, 1998–99 and 1999–2000 growing seasons. Survey data indicated that pasmo was widespread in England and Scotland, causing extensive loss of leaves and stem and capsule symptoms, on both winter and spring linseed crops. In winter linseed experiments at ADAS Boxworth and Rothamsted, when severe epidemics occurred (1997–98 and 1999–2000), control of pasmo with one or two MBC fungicide sprays increased yield. In experiments when severe pasmo epidemics did not occur (1998–99), fungicide applications did not increase yield. In all three growing seasons, large numbers of air-borne Mycosphaerella linicola ascospores were collected in the summer months. At the time when the winter linseed crop was emerging and becoming established in October/November, there were more air-borne M. linicola ascospores in 1999 than in 1998. April/May rainfall was much greater in 1998 (135 mm) and 2000 (223 mm), when severe pasmo epidemics developed by July, than in 1999 (68 mm) when disease severity in July was less. Regression analyses suggested that yield decreased as percentage area affected by pasmo on leaves or stems in July increased. The formulae relating yield loss to pasmo severity, derived from these experiments, were combined with disease survey data to estimate, retrospectively, the UK national losses from pasmo. Estimated national losses from pasmo on winter linseed, although >50% of crops were sprayed with fungicide, were approximately £2.9M in 1998, £1.6M in 1999 and £0.37M in 2000 (when the area of winter linseed had decreased greatly). Estimated combined losses on winter and spring linseed were approximately £14.8M in 1998, £34.9M in 1999 and £11.0M in 2000.     

福建柏地理种源开花与结实变异规律的研究

福建柏1年2次花期,春花期4-5月,果期10月,种子无生活力;秋花期9-10月,果期翌年10月,种子有生活力,有效花期在秋季.种源花期及果期变异规律与适生区的地点、海拔、温度等地理气候因子紧密相关,总体变异规律:秋花期、球果成熟期、种子散落期山区比半山区早,半山区比丘陵区早,高海拔地区比低海拔地区早;同一地点和相同海拔高度,不同种源开花结实物候期相同,球果、种子形态特征及单果重、千粒重、发芽率差异不显著;不同地点和不同海拔高度,种源开花结实的物候期不同,果径、果高、单果重、种子数、千粒重、发芽率等主要指标差异显著或极显著.     

Epidemiology of Leptosphaeria maculans in relation to forecasting stem canker severity on winter oilseed rape in the UK

In the UK, ascospores of Leptosphaeria maculans first infect leaves of oilseed rape in the autumn to cause phoma leaf spots, from which the fungus can grow to cause stem cankers in the spring. Yield losses due to early senescence and lodging result if the stem cankers become severe before harvest. The risk of severe stem canker epidemics needs to be forecast in the autumn when the pathogen is still in the leaves, since early infections cause the greatest yield losses and fungicides have limited curative activity. Currently, the most effective way to forecast severe stem canker is to monitor the onset of phoma leaf spotting in winter oilseed rape crops, although this does not allow much time in which to apply a fungicide. Early warnings of risks of severe stem canker epidemics could be provided at the beginning of the season through regional forecasts based on disease survey and weather data, with options for input of crop-specific information and for updating forecasts during the winter. The accuracy of such forecasts could be improved by including factors relating to the maturation of ascospores in pseudothecia, the release of ascospores and the occurrence of infection conditions, as they affect the onset, intensity and duration of the phoma leaf spotting phase. Accurate forecasting of severe stem canker epidemics can improve disease control and optimise fungicide use.     

Integrated management of faba bean chocolate spot caused by Botrytis fabae in Gondar,Ethiopia

Abstract

Integrated management of faba bean chocolate spot (Botrytis fabae Sard.) was studied using moderately tolerant variety, “Hachalu” and the local cultivar at Chilga district during 2016 main cropping season. The objective was to evaluate effect of host resistance, intercropping and fungicide applications on epidemics of faba bean chocolate spot, yield and yield components of faba bean, and sole and intercrop systems productivity. The experiment was randomised complete block design in a factorial combination of two faba bean cultivars, two cropping systems (Hachalu- and local-barley intercropping in 2:1 ratio) and four levels of fungicide (Chlorothalonil) spray and integration in three replications of faba bean and barley, respectively. Cultivars and spray intervals significantly (p?<?.01) affected the seed yield while cultivars alone had significant variation (p?<?.01) on 100-seed weight as a main effect. Therefore, 21-days fungicide spray intervals integrated with Hachalu sole and Hachalu-barley intercropping may be considered for chocolate spot management.     

Changes in carbohydrates,amino acids and proteins in developing seed of chickpea

Developing seeds of chickpea cultivars G-130, L-550 and 850-3/27 grown under field conditions were sampled at different stages of maturity and analysed for soluble sugars, starch, soluble nitrogen, protein nitrogen and amino acids. Fr. wt of seeds of all three cultivars decreased after 28 days of flowering while the dry wt continued to increase. Rapid starch accumulation was observed between 14 and 28 days after flowering. Starch as per cent of seed dry wt started to decrease after 28 days, while starch per seed increased till maturity. The percentage of salt-soluble proteins decreased with maturation of seed. The electrophoretic pattern revealed that deposition of seed storage protein in cotyledons occurred 14 days after flowering. Most of the biochemical activity apparently occurred between 14 and 28 days after flowering.     

Effects of Bradyrhizobium strain and host genotype,nodule dry weight and leaf area on groundnut (Arachis hypogaea L. ssp. fastigiata) yield

Effects of inoculating four Arachis hypogaea ssp. fastigiata cultivars with 17 Bradyrhizobium spp. strains were studied in a glasshouse experiment using a sandy soil devoid of an indigenous Bradyrhizobium population. Firstly, a wide range of parameters, indicative of symbiotic performance, were assessed for their influence on seed yield, by correlation and statistical analyses. It was found that nodule dry weight and leaf area were relevant parameters concerning seed yield. Secondly, the effects of host and strain genotype on those parameters were described.Variations in nodule dry weight did not have an effect on seed yield, except for cultivar Natal Common at lower nodule dry weight values. Therefore, it was concluded that the quantity of nitrogen fixing tissue met the demand for combined nitrogen and did not limit seed yield. This conclusion was further supported by the observation that at low nodule numbers per plant the nodule size increased to generate sufficient nitrogen fixing tissue.Leaf area, which comprises components for both photosynthetic capacity and plant development, was found to correlate well with seed yield. An increase in leaf area resulted in significant seed yield increases for all three spanish-type cultivars, but not for the valencia-type cultivar. Leaf area, thus, appeared as a factor limiting seed yield of spanish-type groundnuts.Cultivar performance concerning seed yield was significantly better for Natal Common compared to the other three cultivars, while Natal Common had a significantly lower plant (biomass excluding seed) dry weight value.Inoculation with different strains of Bradyrhizobium resulted in significantly different nodule dry weight values, but hardly led to significant differences in seed yield. This agreed with the finding that the amount of nitrogen fixing tissue appeared not to limit the availability of combined nitrogen.A large quantity of nitrogen was partitioned to the groundnut seeds: 62% to 76% of total accumulated nitrogen was located in the seeds.This study showed that testing for symbiotic effectiveness in the groundnut Bradyrhizobium symbiosis should include assessment of final (seed and biomass) yield, because parameters measured at stages prior to maturity, like nodulation parameters, may lead to flawed effectiveness ratings.     

Sesame genotype influences growth and phenology of Phelipanche aegyptiaca

Egyptian broomrape (Phelipanche aegyptiaca) is a parasitic weed causing major yield loss in many field and vegetable crops. Recent observations in Iran suggest that sesame (Sesamum indicum) may serve either as a trap crop or as a host for broomrape, depending on genotype. The central objective of this research was to identify sesame genotypes that could act either as potential trap crops, or sources of genetic material for development of broomrape resistant cultivars. Seeds of 11 Iranian sesame genotypes (Ardestan, Esfarayen, Oltan, Ahvaz, Borazjan, Darab‐14, Ferdous, Kalat, Naz Tak Shakhe, Varamin and Yekta) and 10 foreign genotypes (S16, S21, S23, S25, S4, S5, S6, S7, S8 and S9) were planted with broomrape seeds in pots. At the flowering stage of sesame, tubercle number and dry weight, shoot number and dry weight and shoot height of broomrape were determined. Shoot dry weight, root dry weight and seed yield of sesame were determined at the physiological maturity. The results showed that broomrape growth varied with sesame genotype. Egyptian broomrape dry weight measured from 1.6% (S23) to 35.4% (Kalat) of the dry weight of the sesame on which it grew. Broomrape total dry weight had positive and highly correlation with the root dry weight of the sesame genotype on which it grew. When broomrape planted with the S7, S8, S9, S21 and S23 genotypes produced tubercles, but no shoots on these genotypes. Such genotypes could be used as both trap crops and as breeding‐sources for development of resistant sesame genotypes.     

基于干热风危害指数的黄淮海地区冬小麦干热风灾损评估

全球气候变化背景下,农业气象灾害呈上升态势。干热风灾害发生区域、次数和强度都发生了明显的变化。研究干热风灾害对农作物的影响对于我国农业可持续发展、保障粮食安全等均具有重要的现实意义。利用黄淮海地区68个气象台站1961—2010年的逐日气象资料,和54个农业气象试验站1981—2006年小麦的发育期、产量、干热风灾害等数据,采用公认的中国气象局2007年发布的气象行业标准《小麦干热风灾害等级》中冬小麦干热风灾害指标,计算干热风危害指数,进一步细化发育期,确定冬小麦抽穗前气象条件对气象产量影响的关键气象因子,分离干热风年冬小麦气象产量,构建重度干热风影响下干热风危害指数与冬小麦抽穗—成熟阶段气象条件对气象产量影响的统计模型,进行1981—2006年黄淮海地区冬小麦干热风灾损的评估。结果表明:(1)重度干热风危害下,1981—2006年期间黄淮海各地区冬小麦不同发育时段的干热风危害指数平均在抽穗—开花时段最大,乳熟—成熟时段居中,开花—乳熟时段最小,分别为0.17、0.15和0.14,平均0.15;(2)冬小麦抽穗前气象条件对气象产量影响的关键气象因子为:播种—出苗期间的最低气温、拔节—孕穗期间的平均气温和孕穗—抽穗期间的平均气温,各个单因子相关系数分别为0.64、0.86和0.99,均达到极显著水平。其中播种—出苗的最低气温可决定小麦出苗的迟早和苗情;拔节—孕穗期间,在小花原基形成期—四分体形成期气温偏低可延长小穗、小花分化时间,防止退化,提高结实率;孕穗—抽穗的平均气温偏高有利于提早抽穗,延长后期灌浆时间,且晴天有利于开花授粉;(3)分离干热风年冬小麦气象产量后,构建了重度干热风影响下干热风危害指数与冬小麦抽穗—成熟3个阶段气象条件对气象产量影响的统计模型,验证结果表明该模型客观上能够综合地反映干热风在不同发育阶段对小麦产量的影响。进一步灾损评估表明:重度干热风危害下,黄淮海地区冬小麦减产率在21.52%—39.80%之间,平均为27.83%。