甘肃省主要农作物需水量时空变化特征分析

采用联合国粮农组织(FAO)推荐的Penman-Monteith公式,计算出甘肃省1960～2000年主要农作物(春、冬小麦,玉米,马铃薯)生育期内逐日需水量,统计分析其时空变化特征和不同作物生育期日均需水量变化规律。研究表明,随纬度的增加作物需水量增大,需水量高值区对应甘肃省的干旱、半干旱地区。作物需水量在近40a内呈现下降的趋势,并且河西地区下降趋势明显大于河东。对几种作物的逐日需水量分析发现,出苗～开花期,作物日需水量缓慢增大;开花～乳熟为需水高峰期,进入作物生长旺盛阶段,乳熟期后日需水量迅速下降。     

稻田寄生蜂和鳞翅目昆虫的多样性及变化动态

稻田中的寄生蜂是水稻害虫重要的自然天敌,在生物防治中起重要作用,但是寄生蜂作用的发挥受到许多因素的影响。本文使用马氏诱集器调查了水稻各生育期稻田中寄生蜂和鳞翅目昆虫的种类及数量,分析了水稻生育期对寄生蜂及其主要寄主鳞翅目昆虫数量的影响。结果发现,在水稻各生育期捕获的寄生蜂数量均显著多于鳞翅目昆虫数量。其中姬蜂科、茧蜂科、赤眼蜂科、缨小蜂科及缘腹细蜂科等属于寄生蜂的优势类群,分别占物种总数的11.80%、11.71%、9.18%、15.51%和11.83%。鳞翅目中,螟蛾科、夜蛾科、卷蛾科和蛱蝶科等为优势类群,分别占物种总数的22.32%、20.87%、26.28%和12.75%。随着水稻生育期的变化,寄生蜂数量先上升后下降,在水稻乳熟期达到最大值,显著高于其他7个生育期的结果。寄生蜂科的Shannon多样性指数,辛普森指数无明显的变化,均匀度指数到乳熟期时有所降低(0.790),随后逐渐上升直到收获。鳞翅目昆虫也呈现先上升后下降趋势,水稻扬花期数量最多,与其他生育期间存在显著差异;鳞翅目科的Shannon多样性指数和辛普森指数在分蘖期到抽穗期虽有波动,但各生育期间差异不显著。在水稻抽穗期到蜡熟期,稻田中鳞翅目科的均匀度指数波动较大,多个生育期间存在显著差异。结果表明,水稻生育期对寄生蜂与鳞翅目昆虫发生数量存在一定的影响,在特定生育期间对昆虫丰富度和多样性存在显著的影响。     

Maize maturity and the development of gibberella ear rot symptoms and deoxynivalenol after inoculation

Development of gibberella ear rot disease symptoms and the accumulation of the mycotoxin deoxynivalenol (DON) in maize ears inoculated via the silk with Fusarium graminearum was determined at various times after inoculation. Ten hybrids ranging in maturity from early to late, were inoculated with a conidial suspension in 1993 and 1994 and harvested every 2 weeks for 14 weeks after inoculation. Disease symptom evaluations were conducted on all 10 hybrids; five of these hybrids were further analysed for DON concentrations. Disease symptoms reached a maximum and stabilized by 6 weeks after inoculation, approximately at physiological maturity (35% kernel moisture) for the early hybrids and the late dent stage of maturity for later hybrids. Deoxynivalenol accumulation was correlated with symptom development but did not stabilize at 6 weeks for all genotypes. Hybrid maturity did not influence symptom development or DON accumulation, but environment did. For the evaluation of hybrids, assessments of resistance to fungal invasion and mycotoxin accumulation based on symptom development could be made much earlier than the current 12-14 week harvest time commonly used in inoculated experiments.     

Effects of weather variables on grain mould of sorghum in South Africa

Effects of weather variables of mould development on sorghum grain were studied over three consecutive seasons in South Africa. Five sorghum hybrids planted at different dates ensured developing seeds were exposed to different weather conditions. Incidence of grain mould fungi was determined at harvest by incubating seeds on 2% malt extract agar. Averages of different weather variables (maximum and minimum temperatures, maximum relative humidity, total precipitation and frequency of precipitation) were determined for all permutations of weekly time intervals for a 2-month postflowering period to identify when these variables and pathogen incidence were significantly correlated. Significant correlations were used to develop models to quantify relationships between variables. Significant positive correlations were observed between the incidence of mould fungi and weather 4–6 weeks after flowering in the shorter season hybrid cv. Buster, and 5–8 weeks after flowering in the remaining hybrids. In most hybrids, correlations between the incidence of grain mould pathogens, including Alternaria alternata , Curvularia spp. ( C. lunata and C. clavata ), Fusarium spp. ( F. proliferatum and F. graminearum ), and Drechslera sorghicola , and average minimum temperature, total rainfall and frequency of rainfall were significant ( P =  0·05). In four hybrids, models showing a linear relationship between the logarithm of pathogen incidence and minimum temperature, and in one hybrid, between pathogen incidence and rainfall frequency, were developed. Depending on the hybrid, models that used minimum temperature as predictor described 60–82% of variation in the incidence of pathogens. Frequency of rainfall explained 93% of the variation in pathogen incidence in one sorghum hybrid genotype. Evaluation of the models using an independent data set yielded average prediction errors near zero, indicating that the models were acceptable.     

Tenth international congress of plant protection,Brighton, November 1983

Abstract

Field trials were conducted to control rodent pests of wheat crop by improving bait acceptability through taste enhancers (additives). Egg shell, egg yolk, yeast, minced meat, sheep blood and chicken blood were mixed 2% by weight individually in a bait base of broken rice and wheat flour. Brodifacoum and bromadiolone bait with egg shell additive ranked first, and egg yolk second, in preference over other additive poison baits and poison bait without additive. Poison baiting yielded 93.3% and 86.7% reduction in rodent population with brodifacoum and bromadiolone (0.005% each), respectively. Three baitings, at tillering, flowering and maturity stage of the crop, gave 91.0% tiller damage reduction with brodifacoum and 86.0% with bromadiolone as compared to control (untreated). It is concluded that three poison baitings containing egg shell additive should be initiated at tillering stage followed by flowering and maturity of the wheat crop for increased yield.     

Social science input into IPM

Abstract

Metsulfuron methyl (Ally‐Dupont), a sulphonylurea herbicide, was tested at rates of 0.5–2.0 g a.i./ha for the control of Striga hermonthica (Del.) Benth. in two cultivars of sorghum in pot experiments. There was good to excellent Striga control at 1.0–2.0 g a.i./ha applied either pre‐emergence or post‐emergence to CSH‐1 or N‐13 sorghum. The herbicide was unacceptably toxic to the Striga‐susceptible CSH‐1 cultivar when applied pre‐emergence, thus eroding any benefits of Striga control. In the Striga‐tolerant N‐13 cultivar there were considerable increases in the growth of infected plants. The herbicide was better tolerated from post‐emergence applications by both cultivars, and CSH‐1 plants recovered enough growth from Striga infection to produce grain yields at 1–5 and 2.0 g a.i./ha. Herbicide application at 4 weeks after planting sorghum was less damaging than at 2 weeks. Herbicide safening with 1,8‐naphthalic anhydride did not provide any additional benefits with post‐emergence application. The efficacy of the pre‐emergence herbicide was similar with surface or incorporated application.     

Notice

Abstract

The seasonal occurrence of gram pod borer, Heliothis armigera Hb. in sorghum during cropping periods was studied. The incidence of H. armigera larvae was highest between March and June, 1984. This gradually decreased between July and October, 1984 and was lowest between January and March, 1985. Larval counts were found to be higher on the cultivar CSH 5 than K‐tall. The main crop of first two cropping seasons harboured more larvae than the ratoon crops while in third cropping period there was no significant difference.     

Are pre‐spraying growing conditions a major determinant of herbicide efficacy?

To evaluate the effect of pre‐spraying growing conditions on herbicide efficacy, two years of experimentation were conducted in which Persicaria maculosa plants were exposed to different light intensities for 1–4 days before metribuzin treatment. Specific leaf area, rather than plant growth rate or plant size, was the only parameter that correlated well with herbicide efficacy in both years of experimentation. The negative relationship between the ED₅₀ and the specific leaf area indicates that leaf characteristics might be an important determinant of herbicide efficacy, for instance through an effect on herbicide uptake. In the third year of experimentation this hypothesis was further investigated by raising six cohorts of weed plants at a 1‐week interval and thus exposing them to a range of weather conditions. Clear relationships between uptake and herbicide efficacy were found for a combination of four plant species (Solanum nigrum, Senecio vulgaris, Chenopodium album and Brassica napus) and two herbicides (phenmedipham and bentazone). For phenmedipham, uptake was negatively correlated with global radiation and positively correlated with relative humidity. For the herbicide bentazone the opposite was found. These results were not species‐specific. This study shows the importance of the sensitivity of herbicide × species combinations and indicates that pre‐spraying weather information is relevant for the development of reduced dose rate recommendations.     

Characteristics of infestation of sweet potato by sweet potato weevil Cylas formicarius (Coleoptera: Apionidae)

Studies were conducted to examine the characteristics of infestation of vines of sweet potato plants by the sweet potato weevil, Cylas formicarius (F.). The use of terminal tender vine cuttings, taken even from heavily weevil‐infested sweet potato, to grow a new crop and planting such a crop in plots surrounded by barriers to reduce weevil migration from the outside to the newly planted area, produced a practically weevil‐free crop. On the contrary, crop planted to old vine cuttings in an open field was severely damaged by the weevil. Consequently, crop planted using tender vine cuttings produced significantly more root yield than the one planted to old vine cuttings, irrespective of whether the planting was done in an open field or in an insect‐protected field. Sweet potato weevil infestation of 1‐ to 8‐week‐old plants increased significantly with plant age. The insect preferred sweet potato roots over sweet potato vines when both plant parts were available for infestation. Dipping the vine cuttings for 30 min in carbofuran solution prior to planting protected the newly planted sweet potato crop for up to 6 weeks after planting.     

Eupatorium Weed Species in Australia

Abstract

High temperature together with high rainfall favour infection and development of Erwinia stalk rot of maize (Erwinia chrysanthemi pv. zeae Victoria, Arboleda and Munoz). An attempt was made to correlate temperature, relative humidity, total rainfall and duration of bright sunshine with disease incidence in six maize cultivars during six crop seasons. Temperature and relative humidity did not fluctuate much during the flowering period at the time of disease appearance. Significant differences in total rainfall and duration of bright sunshine were observed. Longer duration of bright sunshine (8.2 h/day) along with moderate rainfall (81.7 mm) were recorded in high disease incidence years. Using these weather conditions a linear equation was derived to predict disease incidence.     

Present Status of Field Pests of Sorghum and Millets in India

Abstract

The incidence, economic importance, ecology, biology and control measures are described in brief for common pests of sorghum and millets in India. At present, shoot flies, stem borers, earhead midges, birds and rats are considered major pests. However formerly occasional or minor pests are becoming a menace in some states due to changes in cultural practices. For most of the recently recorded pests, information on factors responsible for their outbreak, bionomics, yield losses etc. is needed before planning the control operations. As an immediate remedy, chemicals have been used extensively, mainly on high yielding varieties and hybrids of sorghums. It is emphasized that studies should be intensified on varietal resistance, mass rearing techniques, predators and parasites and manipulation of population by cultural practices leading to the possibility of using all available methods on an integrated basis for future pest management programmes for sorghum and millets.     

Soybean stem fly,Melanagromyza sojae (Diptera: Agromyzidae), on Sumatra: Seasonal incidence and the role of parasitism

Abstract

The density of M. sojae and percentage parasitism was studied in unsprayed soybean at 18 farmers’ field sites in Aceh, North Sumatra and West Sumatra provinces, Indonesia, during 1992 and 1993. M. sojae generally infested soybean throughout the season; infestation was initially low, reached its peak from the fifth till the eighth week after planting and declined towards the end of the season. A complex of seven hymenopterous parasiloids had a high impact on the pest. Parasitism levels built up alongside with host density and remained high until just before harvest. The eucoilid Gronotoma sp. was the most prevalent species during the early and mid‐season; a complex of pteromalids became dominant towards the end of the season. In soybean planted successively at 2‐week intervals, the parasitism level in the first‐planted crop built up slowly, whereas the parasitism level in the third‐planted crop was high from the early crop stage onwards, which suggests that the third‐planted crop benefited from parasitism build‐up in the earlier‐planted crops. The role of parasitoids in controlling beanflies in unsprayed soybean is discussed.     

Simulation of damage in winter wheat caused by the grain aphid Sitobion avenae. 3. Calculation of damage at various attainable yield levels

A dynamic, process-based simulation model is used to evaluate the effect of injury bySitobion avenae F. on yield of winter wheat at a range of attainable yield levels. The attainable yield is defined as the yield in the absence of pests and diseases, at the prevailing temperature and radiation and the available amount of soil nitrogen. Water limitation is not taken into account. Only the period from flowering to ripeness is considered. Aphid infestation intensity is expressed in aphid-days, the integral of aphid density (tiller^–1) over time (day). The calculations show that damage per aphid-day decreases from flowering to ripeness because damage caused by honey-dew decreases with advancing crop development stage while damage caused by aphid feeding is about constant. Damage per aphid-day during a particular period of crop development increases in a nearly linear fashion with the attainable yield level. At attainable yield levels over approximately 9000 kg ha^–1 and until crop development stage early milky ripe (DC 73), however, damage per aphid-day increases at a higher rate with the attainable yield level as compared to lower yield levels. The crop-physiological causes are discussed.Regression models are constructed that relate simulated aphid damage both during various periods of crop development and averaged over the entire post-anthesis phase, to the simulated attainable yield level. The accuracy of these simulation-based regression models and five published models of damage in winter wheat caused byS. avenae is evaluated using 21 data sets, obtained in experiments carried out between 1973 and 1984 in the Netherlands. Attention is focussed on two aspects of model accuracy: the agreement between predicted and measured damage and the size of the error in model predictions. In both aspects the simulation-based regression models are as good as the best published empirical models.     

Fusarium graminearum and Fusarium pseudograminearum caused the 2010 head blight epidemics in Australia

Wheat crops in southeast Queensland (Qld) and northern New South Wales (NSW) were infected with fusarium head blight (FHB)‐like symptoms during the 2010–11 wheat growing season. Wheat crops in this region were surveyed at soft dough or early maturity stage to determine the distribution, severity, aetiology and toxigenicity of FHB. FHB was widespread on bread wheat and durum, and Fusarium graminearum and/or F. pseudograminearum were diagnosed from 42 of the 44 sites using species‐specific PCR primers directly on spikelets or from monoconidial cultures obtained from spikelets. Stem base browning due to crown rot (CR) was also evident in some samples from both states. The overall FHB and CR severity was higher for NSW than Qld. Deoxynivalenol (DON) concentration of immature grains was more than 1 mg kg^?1 in samples from 11 Qld and 14 NSW sites, but only 13 of 498 mature grain samples sourced from the affected areas had more than 1 mg kg^?1 DON. DON concentration in straw also exceeded 1 mg kg^?1 in eight Qld and all but one NSW sites but this was not linked to DON concentration of immature grains. The proportion of spikelets with positive diagnosis for F. graminearum and/or F. pseudograminearum and weather‐related factors influenced DON levels in immature grains. The average monthly rainfall for August–November during crop anthesis and maturation exceeded the long‐term monthly average by 10–150%. Weather played a critical role in FHB epidemics for Qld sites but this was not apparent for the NSW sites, as weather was generally favourable at all sites.     

Susceptibility of winter wheat cultivars to wheat ear insects in Central Germany

The intensity of thrips and wheat blossom midges (WBM) infestations in twelve wheat cultivars was evaluated at the Plant Breeding Station, Silstedt, central Germany in 2008 & 2009 growing crop seasons. The research aimed at selecting the least infested cultivar to be profitably used in the forthcoming cultivation. Infestation levels were studied in flowering and milky stages (GS 65 and 73) of each cultivar in every single-spikelet in sample of 10 ears in both years. There were significant differences in thrips and (WBM) densities among different cultivars in both years. Thrips numbers were the highest in T??rkis, Global and Esket cultivars, while the lowest values were recorded in Robigus, Brompton and Carenius. The results showed that the highest WBM infestation was observed in T??rkis, Tommi and Potenzial; on the other hand the lowest WBM infestation was found in some insect resistant cultivars (Brompton, Skalmeje, Robigus, Welford and Glasgow). The infested ears were positively correlated with the numbers of WBM among cultivars. The obtained results would give a good guide for choosing the proper cultivars which proved highly resistant to their specific pests.     

东北三省春玉米旱灾动态风险评估

干旱演变趋势的不确定性决定了旱灾风险的动态变化特征,如何采用有效的方法探究风险随时间的变化是评估旱灾动态风险的关键。由于干旱发生发展缓慢,长时间尺度数值预报产品精度较低,用于干旱预报有一定的局限性。本研究选用天气发生器随机生成未来逐日气象数据的大量样本预测干旱演变趋势,驱动作物模型评估不同趋势下作物产量因旱损失及动态风险。选取东北三省为研究区,在2012—2017年田间试验数据的基础上,率定及验证APSIM作物模型,利用BCC/RCG-WG天气发生器随机生成未来气象数据,驱动APSIM作物模型模拟春玉米产量因旱损失,计算期望产量因旱损失率,以典型干旱年2000年为例,实时动态评估东北三省春玉米生育期内（5月1日—9月18日）旱灾动态风险。结果表明：（1）APSIM作物模型模拟春玉米播种到开花日数、生育期日数以及产量与试验观测结果决定系数R²均大于0.5,标准均方根误差NRMSE均在10%以下,表明APSIM模型在东北三省模拟春玉米生长效果较好;BCC/RCG-WG天气发生器生成100个气象要素样本与1961—2020年各气象数据年均值R²均在...     

Flowering behaviors of the inflorescences of an alien plant (Plantago asiatica), an alpine plant (Plantago hakusanensis), and their hybrids on Mt. Hakusan,Japan

In the subalpine zone on Mt. Hakusan, Japan, Plantago asiatica, an alien plant, and Plantago hakusanensis, a native alpine species, grow sympatrically along with their putative hybrids. Here, their flowering behavior, which affects the frequency of hybridization and the colonizing ability of P. asiatica and its hybrids, is described. The flowering behavior of each species and of two F₁ hybrids from different seed parents was determined based on the position of the flower in the inflorescence by using a generalized linear mixed model. The percentage fruit set of individually bagged inflorescences was calculated to corroborate the assumptions of the opportunities for self‐pollination. All the flowers were protogynous; however, many P. asiatica anthers dehisced before browning of the stigma in the flower and the sex presentations in the inflorescence were asynchronous. The percentage of fruit set was high. Consequently, P. asiatica has the opportunity for self‐pollination within the flower and in the inflorescence. In contrast, the P. hakusanensis anthers dehisced after browning of the stigma in the flower; their sex presentation was synchronous in the inflorescence, showing negligible opportunities for self‐pollination, and the fruit set was low. Accordingly, in the field, P. hakusanensis might require pollination among the inflorescences for seed production and be actively outcrossed, while P. asiatica is able to outcross in the early flowering phase. Therefore, P. asiatica and P. hakusanensis have opportunities for hybridization. The F₁ hybrids exhibited intermediate flowering behavior and produced fruits, demonstrating the potential to reproduce by selfing.     

Arthropod populations and rice yields in direct-seeded and transplanted lowland rice in West Africa

Studies were conducted on the effect of pruning time, host age, urediniospore release and weather parameters on the incidence and intensity of mulberry leaf rust (Peridiopsora mori). Rust severity significantly increased with increasing shoot age, irrespective of pruning time. Maximum disease severity was observed in plants pruned during the third week of October, and minimum severity in plants pruned during last week of November. Apparent infection rate was higher in younger shoots. Infection rate was higher in plants pruned during the last week of November. Urediniospore release was influenced by prevailing climatic conditions. A higher rate of spore release was noticed during sunny days. Maximum spore release was found between 12.00 h and 14.00 h. Spore release was positively correlated with temperature and negatively correlated with relative humidity. Rust severity (34.97%) was higher in January and least (1.03%) during May. Rust severity was negatively correlated with both temperature and rainfall. An exponential model was developed for the prediction of rust severity which was accurate up to 96.60%.     

Effectiveness of insecticide-treated and non-treated trap plants for the management of Frankliniella occidentalis (Thysanoptera: Thripidae) in greenhouse ornamentals

The effectiveness of trap cropping as an integrated control strategy against western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), was explored in potted chrysanthemum, Dendranthema grandiflora (Tzvelev), greenhouse crops. The efficacy of flowering chrysanthemum trap plants, either treated with the insecticide spinosad or untreated, to regulate F. occidentalis populations was tested at different spatial scales (small cage, large cage and commercial greenhouse) and for different time periods (1 or 4 weeks). It was demonstrated that flowering chrysanthemums as trap plants lower the number of adult F. occidentalis in a vegetative chrysanthemum crop and, as a result, reduce crop damage. In the 4 week large-cage trial and the commercial trial, significant differences between the control and the trap plant treatments started to appear in the third week of the experiment. Larvae were only significantly reduced by the presence of trap plants in the 1 week small-cage trials. There were no significant differences between treatments with spinosad-treated and untreated trap plants in the number of F. occidentalis on the crop. This suggests that there was minimal movement of adult F. occidentalis back and forth between the trap plants and the crop to feed and oviposit. It is concluded that the trap plant strategy is a useful tool for integrated pest management against F. occidentalis in greenhouses.