共查询到19条相似文献，搜索用时 171 毫秒
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小菜蛾为害不同生育期秋甘蓝对产量的影响及经济阈值研究 总被引：1，自引：0，他引：1
采用笼罩法测定了小菜蛾在秋甘蓝不同生育期为害造成的产量损失,建立了产量损失率与小菜蛾虫口密度的回归关系式。结果表明,在秋甘蓝苗期、莲座期、结球始期和结球中后期秋甘蓝损失率(y)与小菜蛾虫口密度(x)关系式分别为:y=9.480 6x-2.586 2,y=3.621 8x-0.790 2,y=-0.210 7x2+6.698 1x-1.906 5和y=0.081 1x2-0.147 9x+0.405 4。根据经济阈值模型,秋甘蓝不同生育阶段的小菜蛾幼虫经济阈值分别为苗期0.54头/株,莲座期0.91头/株,结球始期0.67头/株,结球中后期6.08头/株。该研究为秋甘蓝小菜蛾的防治策略和经济阈值的确定提供了科学依据。 相似文献
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种子带毒率及有翅蚜降落量对SMV流行的影响 总被引：2，自引：0，他引：2
大豆田主要迁飞降落的蚜虫有大豆蚜、棉蚜、玉米蚜、桃蚜、禾谷缢管蚜、豆蚜等,而大豆蚜的数量占绝对优势。当有翅蚜迁飞降落量大,同时田间病株率高时,SMV日侵染率高,最高达49.57%。田间有翅蚜发生和迁飞降落高峰一般在7月份,此时的迁飞降落蚜量和SMV的种子带毒率决定病害流行的程度。0.5%种子带毒率显著推迟SMV流行的时期。田间有翅蚜发生和飞翔高峰期推迟到8月份,0.2%和0.1%种子带毒率可控制SMV的流行为害。 相似文献
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甘蓝蚜危害油菜产量损失的研究 总被引：1，自引：1，他引：0
作者用一种衡量蚜虫危害的新尺度——“累计蚜量(头/天)”,对油菜不同生育阶段的单株损失及补偿作用分别作了研究。结果表明:油菜苗期、苔花期、荚果期都存在着一个造成损失的临界危害量(C)。苗期 C 为360～440(头/天),苔花期 C 为13500～16500(头/天),荚果期 C 为2700～3300(头/天)。危害量与损失率的关系符合 logistic 曲线。根据研究结果提出“有害株”的概念,既有蚜虫而又影响产量的植株。并结合蚜虫消长规律及累计蚜量的计算原理推导出确定“有害株”蚜量标准的公式B=C/(1/2)T(1+Q~n)+ITQ(1-Q~(n-1))/(1-Q)经比较,认为“危害株率”是蚜虫防治指标理想的尺度,它不仅明确可靠,而且简单易行。 相似文献
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稗草生长明显降低了大豆籽粒蛋白质产量及氮素向其籽粒中的分配比例，而显著提高了大豆茎、叶、籽含氮量及氮素向其茎、叶中的分配比例，这种影响在座荚期渍涝＋鼓粒期干旱条件下最为突出：稗草对大豆籽粒蛋白质生产的危害在功苗期一开发期的渍涝条例上显著减轻，而在任一时期的干旱条条件下均明显加重，且在座荚期的渍涝处理中比在幼苗期一开发期的渍涝处理中大。不同时期、不同旱涝胁处理对大豆籽粒蛋白质产量的降低程度不同，其中 相似文献
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稗草生长明显降低了大豆籽粒蛋白质产量及氮素向其籽粒中的分配比例,而显著提高了大豆茎、叶、籽含氮量及氮素向其茎、叶中的分配比例。这种影响在座荚期渍涝 鼓粒期干旱条件下最为突出;稗草对大豆籽粒蛋白质生产的危害在幼苗期—开花期的渍涝条件下显著减轻,而在任一时期的干旱条件下均明显加重,且在座荚期的渍涝处理中比在幼苗期—开花期的渍涝处理中大。不同时期、不同旱涝胁迫处理对大豆籽粒蛋白质产量的降低程度不同,其中旱害远大于涝害,后期旱害大于前期旱害,先涝后旱的危害大于先旱后涝的危害,旱涝结合的危害大于只旱或只涝的危害;开花期大豆最不耐涝,鼓粒期最不耐旱。 相似文献
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大豆花叶病流行因素和发生预测研究 总被引：3，自引：0，他引：3
1984—1989年于济南研究诸因素对病害流行的作用。研究表明,大豆品种抗性和初始毒源数量为病害流行的主导因素。大豆幼苗期最感病,开花期为发病高峰。在春大豆苗期温度偏高雨量偏少及夏大豆苗期温度偏低雨量偏多的情况下,有利花叶病发生。对13种蚜虫进行饲毒接毒试验,证明桃蚜(Myzus persicae)、豆蚜(Aphis craccivora)和大豆蚜(Aphisglycines)可传毒,对病害田间流行有重要影响。对5年的16组数据应用IBM微机进行逐步回归和通径分析,组建发生预测模型。 相似文献
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不同小麦品种资源苗期和成株期麦长管蚜抗性鉴定和分析 总被引：2，自引：2，他引：0
为明确小麦苗期和成株期与麦长管蚜抗性的关系,2010—2012年采用蚜量比值法对94个小麦品种进行了温室苗期人工接种和田间成株期自然感蚜麦长管蚜抗性鉴定。结果表明,43个品种连续3年在成株期对麦长管蚜表现不同程度的抗性,其中高抗品种2个,中抗品种8个,低抗品种33个;45个品种在苗期对麦长管蚜表现不同程度的抗性,其中高抗品种5个,中抗品种16个,低抗品种24个;30个品种在苗期和成株期同时表现抗蚜,占供试品种的31.91%,其中C273和兰麦（陕西柞水）在苗期和成株期均表现为高抗;小麦品种在温室苗期人工接种和田间成株期自然感蚜的蚜量比值呈极显著正相关,苗期和成株期麦长管蚜抗性表现一致的共有66个品种,占供试材料的70.21%。研究表明温室苗期人工接种是快速鉴定小麦品种麦长管蚜抗性的有效方法。 相似文献
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为确定我国草地贪夜蛾 Spodoptera frugiperda重点防范区——黄淮海夏玉米区该虫为害籽粒玉米的防治阈值,于2020—2021年分别在籽粒玉米小喇叭口期（6~8叶）、大喇叭口期（8~10叶）和抽雄吐丝期 （12~14叶）,通过人工接草地贪夜蛾2龄幼虫进行田间试验,分析不同虫口密度和为害株率下玉米的产量损失,并确定相应防治阈值。结果显示,草地贪夜蛾2龄幼虫密度为2~12头/株时,小喇叭口期、大喇叭口期和抽雄吐丝期的玉米产量损失率分别为16.78%~31.91%、 10.45%~25.14%和15.71%~29.17%,在3个玉米生育期对草地贪夜蛾的防治阈值分别为2龄幼虫55~67头/百株、 97~118头/百株和59~71头/百株;当草地贪夜蛾2龄幼虫为害株率为5%~60%时,小喇叭口期、大喇叭口期和抽雄吐丝期的玉米产量损失率分别为8.81%~22.43%、 4.83%~17.75%和8.16%~20.43%,在3个玉米生育期对草地贪夜蛾的防治阈值为害株率分别为4.24%~5.22%、 7.61%~9.49%和4.46%~5.55%。表明黄淮海夏玉米区草地贪夜蛾在不同生育期为害籽粒玉米的产量损失和防治阈值不同。 相似文献
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Soybean yields, pod and branch numbers were inversely related to the height of velvetleaf (Abutilon theophrasti). This effect was attributed to increasing interception of light with increasing height of A. theophrasti. Reduction; in soybean yield and yield components were greater if A. theophrasti was maintained at various heights for only 3 weeks rather than 6 weeks following soybean emergence. This effect was attributed to a longer duration of light competition by the weed. Even when the A. theophrasti canopy was kept 25% below that of soybean for 4 weeks, soybean yields, pod and branch numbers decreased when the weed was allowed to regrow during the remainder of the season, but not if the weed was removed after the initial 4-week clipping period. No reduction in seed yields, pod and branch numbers was noted if A. theophrasti plants 25% shorter than soybeans were removed or allowed to resume growth after the initial 6 or 8 weeks of clipping. Soybean seed size was slightly affected by A. theophrasti canopy height and duration of competition. 相似文献
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Three field experiments were conduced to evaluate the effect of Abutilon theophrasti on dry matter, branching and flowering node, and seed production of soybean. Low populations (2.4–4.7 plants m?2) of the weed reduced soybean dry matter, flowering node and seed production. The effect was most pronounced on soybean seed yield, and less on flowering node and dry weight production. These effects were due to the presence of A. theophrasti with soybean, and not to changes in plant population. The effect on soybean branching node production was inconsistent between years. 相似文献
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Hidenori Asami Gen Ishioka Masaaki Tachibana Koki Homma 《Weed Biology and Management》2023,23(1):14-22
The spread of morning glory (Ipomoea spp.) in soybean fields in Japan has severely decreased soybean yield. Yet, current control measures do not control the proliferation of Ipomoea spp. As little is known about the flowering period and seed production among the different invading Ipomoea spp., it is challenging to create targeted control measures based on ecological characteristics. This study aimed to reveal the characteristics of the flowering phenology and seed production of four morning glory species, namely, Ipomoea coccinea L. (red morning glory), Ipomoea lacunosa L. (pitted morning glory), Ipomoea hederacea L. Jacq. var. integriuscula A. Gray (entireleaf morning glory), and Ipomoea triloba L. (three-lobe morning glory). Between 2017 and 2019, the four selected study species were grown under similar conditions of soil quality, irrigation, and environmental influences and their flowering phenology and seed data were recorded. The flowering period ranged from 36 to 40 days, and the initial flowering of I. triloba was approximately 2 weeks later than the others. I. coccinea had the highest flowering number and seed production, followed by I. lacunosa, I. triloba, and I. hederacea var. integriuscula. The fruit setting rate of I. triloba decreased later in the reproductive stage but tended to increase as the daily mean temperature increased on each flowering day. Thus, we report that the flowering phenology and seed production differed greatly among the Ipomoea spp. These findings can provide crucial insights into designing targeted species-specific control measures against the spread of Ipomoea spp. in Japan. 相似文献
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The critical period of weed interference in one variety of chickpea was determined in field experiments carried out at two sites, Tabriz 2002 and Kermanshah 2003, Iran. Chickpea culture was either kept free of weeds for 0, 12, 24, 36, 48 and 60 days after crop emergence (DAE) or weeds were allowed to grow for 0, 12, 24, 36, 48 and 60 DAE. In these experiments, chickpea yield increased with increasing duration of weed-free period and was reduced by increasing duration of weed-infested period. Unweeded conditions for the entire growing season caused 66.4% and 48.3% seed yield reduction when compared with the treatment that was weed-free throughout the growing season, at Tabriz 2002 and Kermanshah 2003, respectively. The results indicated that chickpea must be kept weed-free between the five-leaf and full flowering stages (24–48 DAE) and from the four-leaf to beginning of flowering stages (17–49 DAE) at the two sites, respectively, in order to prevent >10% seed yield loss. At both sites, reduction in seed yield, because of the increased weed interference period, was accompanied by simultaneous reduction in plant dry weight, number of branches, pods per plant and 100-seed weight. This was supported by significant and positive correlations between these traits and chickpea seed yield. There was no significant correlation between the number of seeds per pod and seed yield. A linear regression model was used to describe the relationship between weed dry weight and seed yield loss. 相似文献
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Field experiments with the synthetic insecticides, Methomyl and Carbaryl, alone and in combination with the biological control agents, Bacillus thuringiensis (Bt) and Trichogramma evanescens, were conducted to control pests in yardlong beans, Vigna sesquipedalis, during the dry season 1998/1999. The experimental area was located at the Central Luzon State University in the province of Nueva Ecija on the Philippine main island Luzon. Carbaryl was applied against bean flies 5 days after plant emergence. Methomyl was sprayed against pod sucking insects and the bean podborer, Maruca vitrata, 45 days after plant emergence. The biological control agents were applied with the beginning of the flowering stage of V. sesquipedalis, when plants were first attacked by M. vitrata.Major insect pests on V. sesquipedalis were cowpea aphid (Aphis craccivora), leafminer (Liriomyza sp.), and bean podborer (M. vitrata). Both, Bt and T. evanescens had no significant impact on yield. M. vitrata eggs, exposed for 48 hours in the fields to augmented T. evanescens, were used to measure field efficacy of the parasitoid. Highest parasitism rate was 13.3%, thus, generally low.Highest yield was obtained from plots treated with both synthetic insecticides. No significant difference in fresh pod yield was observed when, in addition to the synthetic insecticides, Bt and/or T. evanescens was applied. However, all treatments significantly out-yielded the untreated control. 相似文献
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Aspects of the population: dynamics of Striga hermonthica (Del.) Benth. on pearl millet (Pennisetum americanum (L.) K. Schum.) were studied in Sahelian Mali. Seasonal development was recorded and density-dependent mortality and fecundity in post-emergent populations investigated. An attempt was also made to assess yield loss due to S. hermonthica attack using a regression approach. The first S. hermonthica plants emerged 42 days after crop germination, and the minimum time to complete the life cycle from emergence was 56 days. Results indicated a premature mortality of 66% in emerged populations. The growth stage reached by the time of host plant death appeared to be important in determining survival to maturity, premature mortality being greatest in plants that had not reached flowering by this time. The potential seed output per plant was estimated at 10 985. There was no evidence that the fecundity of S. hermonthica was affected by the density of emerged populations. Regression models showed a significant relationship between millet yield and emerged S. hermonthica density. The results suggest that lower densities give a relatively larger decrease in yield per S. hermonthica plant. The results of the study are discussed in relation to their implications for control. 相似文献
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Genetics of resistance to soybean cyst nematode (SCN), Heterodera glycines Ichinohe is very complex. Crosses involving PI 437654, which is resistant to all races of cyst nematodes with other sources of resistance (Peking, PI 88788, and PI 90763) indicated that resistance to race 3 was controlled by four genes, two of which were dominant resistance genes and the other two were recessive resistance genes. For race 5, a four gene model with two recessive and two dominant resistance genes in epistasis has been proposed. For race 14, the results suggested a three gene model with one dominant and two recessive alleles. Several other plant introductions have been isolated which have different genes conditioning resistance. Most of the currently grown soybean varieties derived resistance from Peking and/or PI 88788. Resistance to SCN in these soybean varieties has broken down because of the emergence of several new races and populations of SCN. The use of PI 437654 or Hartwig and other plant introductions with different genes for resistance will broaden genetic diversity and stabilize yield. 相似文献
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不同耕作方式对北疆夏大豆荚粒空间分布及产量的影响 总被引：1，自引：0，他引：1
采用大区试验设计,研究滴灌条件下翻耕覆膜(TP)、翻耕(T)、旋耕(RT)、免耕(NT)四种耕作方式对北疆复播大豆的农艺性状、单株荚数、粒数的空间垂直分布、每荚粒数及产量的影响。结果表明,夏大豆的主要农艺性状基本表现为土壤实施耕作处理均优于免耕,其中以翻耕覆膜的效果最好,翻耕次之;单株荚数和粒数的空间垂直分布因耕作方式而异,翻耕覆膜、翻耕、旋耕的主要分布于主茎的中层和上层,免耕的主要分布于主茎中层和下层;不同荚粒的数量均与单株产量呈正相关,其中2粒荚和3粒荚的数量是构成不同耕作方式单株产量的主体,相关系数分别为r=0.99**和r=0.98**;各类荚的数量均以翻耕覆膜的最多,使得其单株荚数和单株粒数的数量均最多,与其它各处理均达极显著差异水平(P0.01),其产量分别比翻耕、旋耕、免耕的增产7.43%、10.85%和16.05%。 相似文献