美洲斑潜蝇对四季豆的危害损失及防治指标研究

研究结果表明,美洲斑潜蝇危害四季豆时,虫情指数与产量损失率之间有极显正相关,其直线回归方程为Y＝0．7399＋1．0185X,r＝0．9980^**。防治指标：当虫情指数为9．504－19．725时,必须用药防治,控制其为害。     

昆嵛山腮扁叶蜂发生与赤松纯林林分因子的关系

为了解林分因子与昆嵛山腮扁叶蜂发生的关系,为昆嵛山赤松纯林的营林措施和昆嵛山腮扁叶蜂的防控技术提供理论指导,本研究在昆嵛山区域选取林龄相对一致(34±2 a)的赤松纯林为对象,调查林分密度、郁闭度、草本盖度、树高、枝下高、胸径、冠幅7个林分因子以及昆嵛山腮扁叶蜂虫巢数。依据虫情指数的分布范围,将样地分为4组,通过方差分析和多重比较研究了4组样地中各项林分因子的差异性。采用逐步回归法,筛选出影响昆嵛山腮扁叶蜂虫情指数的关键因子,在此基础上通过偏相关分析和单因素方差分析法进一步阐明关键因子与虫情指数之间的关系。结果表明,7个林分因子在4组样地中均存在极显著的组间差异。逐步回归筛选出冠幅、枝下高和林分密度为影响昆嵛山腮扁叶蜂发生的关键因子,根据关键因子建立了虫情指数的线性预测方程。冠幅和枝下高对昆嵛山腮扁叶蜂虫情指数的影响均达到极显著正相关水平(P0.01),林分密度对昆嵛山腮扁叶蜂虫情指数的影响为极显著负相关(P0.01)。影响虫情指数的关键因子可能会因林分的不同而不一致,因此要根据关键因子调整林分结构,以达到控制虫害流行的目的。     

豆天蛾对大豆为害产量损失的研究

本文通过测定大豆的不同虫口密度与产量损失的关系,研究了3龄幼虫后所造成的不同产量损失。笼罩条件虫量(x)与产量损失率(y)的回归方程,=1.55+0.43x±0.6643,r=0.9943~(**);笼罩条件虫量(x)与结荚损失率(y)的回归方程,=15.11+0.35x±1.9544,r=0.9466~(**)。     

利用`虫（螨）日‘建立时间动态经济受害水平的研究方法

本文以苹果叶螨为研究材料,阐述了应用‘虫(螨)日’建立时间动态经济受害水平的方法。研究表明:第一,由于虫(螨)日指数概括了害虫(或害螨)危害的基本过程,故由虫(螨)日与产量损失率作出的EIL和ET模型将更为可靠;其次,所得EIL和ET不是某时刻的单一虫(螨)口密度指标,而是时间动态的虫(螨)口密度和累积虫(螨)日指数综合指标;第三,这种建模方法不必考虑虫(螨)的自然存活率。     

二代玉米螟为害玉米产量损失研究

【目的】研究二代亚洲玉米螟Ostrinia furnacalis(Guenee)为害对玉米产量的影响。【方法】以"先玉335"为供试玉米品种,通过人工接虫模拟二代玉米螟不同发生量为害玉米对产量损失的影响。【结果】随着接卵量增加,虫孔数和蛀孔隧道长度增加,玉米单穗粒重降低。单株虫孔数每增加1个,玉米产量损失率增加4.52%;隧道长度每增加10 cm,产量损失率增加8.34%。接卵量与玉米产量损失率的关系符合方程z=-10.0297+4.034 ln(x)。【结论】根据害虫经济阈值的定义,推算出二代玉米螟的防治指标为百株累积卵量12.8块,对二代玉米螟的防治决策具有重要指导作用。     

豆天蛾田间饲养量及效益研究

通过对豆天蛾在田间笼罩条件下的饲养调查观察 ,测定出其幼虫食叶量、食叶率 ,从而计算出每平方米豆田的理论养虫量 ,实际适宜养虫量及对大豆产量损失的影响。笼罩条件养虫量 (x)与食叶率(y1)回归方程 :^y1=2 2 0 + 2 4 1x± 2 874 9,r1=0 9971 ;笼罩条件养虫量 (x)与产量损失率 (y2 )回归方程 :^y2 =1 5 7+ 0 4 2 5x± 0 6 837,r2 =0 994 6 ;笼罩条件养虫量 (x)与结荚损失率 (y3 )回归方程 :^y3 =1 5 7+ 0 33x± 1 785 4 ,r3 =0 94 6 8 。在幼虫饲养量为 1 0～ 1 5头 m2 时 ,综合效益比一般豆田每 6 6 7m2增收 4 73 6元以上。     

植物耐虫性的研究方法

本文介绍了植物耐虫性的研究方法, 包括植物功能损失指数(耐虫指数)、产量损失率、植株被害率、存活率、根系体积(受害程度)、植株和害虫干重、叶片叶绿素荧光特性、保护酶活性和主茎伤流液量等生理生化指标以及害虫的种群发展和取食行为等方法, 并提出植物耐虫性机理的研究思路和方向。     

植物耐虫性的研究方法

本文介绍了植物耐虫性的研究方法,包括植物功能损失指数(耐虫指数)、产量损失率、植株被换害率、存活率、根系体积(受害程度)、植株和害虫干重、叶片叶绿素荧光特性、保护酶活性和主茎伤流液量等生理生化指标以及害虫的种群发展和取食行为等方法,并提出植物耐虫性机理的研究思路和方向.     

辽宁省二代亚洲玉米螟为害防治的经济阈值

为探明二代亚洲玉米螟发生量对玉米产量损失的影响,本试验在田间采用人工密度梯度接卵法(0、20、50、100和200块·百株-1),模拟自然情况亚洲玉米螟发生量,研究辽宁地区二代亚洲玉米螟(Ostrinia furnacalis Guenée)对玉米的经济阈值。结果表明:百株接卵量与虫孔数呈极显著正相关(P0.01),百株虫孔数与产量损失率呈极显著正相关(P0.01),回归方程分别为y=3.1999x+24.8416(R2=0.953,P0.01),y=0.0234x-1.6167(R2=0.988,P0.01),推导出百株接卵量与玉米产量损失率的方程为z=0.0749x-1.0354,即落卵量每增加1块,虫孔数增加约3.2个,产量损失率增加7.49%;隧道长度与雌穗长度、穗粗及粒重呈极显著负相关(P0.01),与产量损失率呈极显著正相关(P0.01),表明玉米茎秆隧道长度每增加10 cm,玉米平均减产7.02 g,产量损失率平均增加4.38%;根据经济阈值定义,在产量8411 kg·hm~(-2)的玉米田,使用松毛虫赤眼蜂(Trichogramma dendrolimi Matsumura)进行单次防治时,辽宁地区防治二代亚洲玉米螟的经济阈值为百株玉米累计落卵量17.39块。     

再生稻褐飞虱为害损失测定和防治指标的研究

在福建,褐飞虱是再生稻的重要害虫,中进行了再生稻褐飞虱为害损失的测定,并对褐飞虱为害再生稻造成的产量损失结构进行了通径分析。根据虫量和产量损失的关系,结合现行稻谷价格,产量水平,防治费用等因素。确定允许为害损失率,同时建立了再生稻褐飞虱防治指标模型,按照防治指标模型,制定出不同产量水平的防治指标。     

南美斑潜蝇为害大棚芹菜和芸豆的产量损失测定及经济阈值分析

研究结果表明：①南美斑潜蝇为害大棚芹菜和芸豆,其虫道面积和产量呈负相关,与产量损失率呈正相关;②曲线回归方程为：Y（大棚芹菜产量）＝4．233／（1＋0．2669e0.0281X）,Y（大棚芸豆产量）＝500950．702／（1＋39262,76541e^0.0103X）,Y（大棚芹菜产量损失率）＝68．075／（1＋23．1517e^-0.071X）,Y（大棚芹菜产量损失率）＝71．765／（1＋4．26245e^-0.0305X）;③经济阈值模型为：X（大棚芹菜）＝14．0845ln[23.1575L/(68.075-L)],X(大棚芸豆）＝27．3973ln[4.26245L/(71.765-l)]。     

Estimation of economic injury level of Aphis craccivora Koch. (Homoptera: Aphididae) infesting faba bean in new reclaimed area

This work was based on field screening procedure to detect the population density of Aphis craccivora for two successive seasons (2004–2005) and (2005–2006) to emphasis the relation between the economic injury level (EIL) and yield loss.

Results obtained showed that the equilibrium position (steady point) during the first and second season was 9.06 and 3.32 individuals/five leaflets, respectively, while the injury level was 3.4 and 1.16 individuals/leaflets. When the bean plant was subjected to three successive insecticidal applications during the early growing, season is sufficient to decrease the yield loss significantly (yield capacity 21.43 Ard./fed.) with comparing to untreated plant (14.98 Ard./fed.), while the plants exposure for one treatment was 17.36 Ard./fed. The EIL was 8.6 individual of aphids/plant depending on the market price of bean and control cost during the season.     

Stomatal numbers of soybean and response to water stress

The relationship among stomatal density, photosynthetic rate, leaf conductance, plant growth, bean yield and kaempferol triglucoside (K9) in the leaves of soybean (Glycine max (L.) Merr.) was examined in two field tests. K9 in the leaves was associated with reduced stomatal density, reduced photosynthetic rate, reduced stomatal conductance, reduced plant weight and lower bean yield. Plants with high stomatal frequency (lacking K9) were better able to take advantage of increased water supply by increasing stomatal conductance (upper surface), transpiration and bean yield. Plants with low stomatal frequency (with K9) were unresponsive to irrigation and in this sense were more tolerant of water stress, but their overall yield was low.     

Yield loss of faba bean (Vicia faba) due to chocolate spot (Botrytis fabae) in sole and mixed cropping systems in Ethiopia

Two field experiments were conducted during 2004 and 2005 cropping seasons at Adet Agricultural Research Center, Ethiopia to assess yield losses caused by chocolate spot(Botrytis fabae) of faba bean in sole and mixed cropping systems using two cultivars. Cropping systems were sole faba bean (FB), faba bean mixed with field pea (FB: FP), barley (FB: BA) and maize (FB: MA). Mancozeb was sprayed at the rate of 2.5 kg a.i/ha at 7-, 14- and 21-day interval to generate different levels of chocolate spot disease in all the four cropping systems, and unsprayed control was also included. The treatments were arranged in a randomised complete block design (RCBD) with four replications. FB: MA mixed cropping significantly reduced disease severity and the area under disease progress curve (AUDPC) and increased faba bean grain yield. The highest faba bean grain yield among the three mixed croppings under different spray schedules was obtained from FB: MA mixed cropping in both 2004 and 2005 (2.56 and 3.74 t/ha, respectively) cropping seasons. There were highly significant yield differences (P < 0.05) among the spray intervals of mancozeb in both seasons. The highest grain yield (4.9 t/h) was recorded from the 7-day spray interval in 2005. The unsprayed faba bean had a lower grain yield (1.9 t/ha in 2004 and 2.3 t/ha in 2005) compared to the sprayed plots. The highest relative yield loss (67.5%) was calculated in 2005 from FB: FP mixed cropping in unsprayed plots. The relative yield losses in the unsprayed plots were in the range of 35.8–41.5% in 2004 and 52.6–67.5% in the 2005 cropping season. Severity and AUDPC were inversely correlated with faba bean grain yield. Significant differences were recorded in the 100-seed weight and days to maturity (DM). The unsprayed plots had shorter DM ranging from 126 to 128.5 day (except FB: MA mixed cropping) in 2004 and 122–123.9 days in 2005. In the sprayed plots DM was relatively longer than the unsprayed plots. A higher seed weight was recorded in the sole FB (56 g) and FB: MA (55 g) mixed cropping, and the lowest value of 100-seed weight was recorded from FB: FP (53 g) mixed cropping. The productivity of the mixed cropping evaluated by land equivalent ratio (LER) exceeded that of sole cropping. Faba bean grain yield was highly influenced by the severity of chocolate spot. The disease affects the DM, forcing early maturing of the plants.     

Substrate-dependent auxin production by Rhizobium phaseoli improves the growth and yield of Vigna radiata L. under salt stress conditions

Rhizobium phaseoli strains were isolated from the mung bean nodules, and, the most salt tolerant and high auxin producing rhizobial isolate N20 was evaluated in the presence and absence of L-tryptophan (L-TRP) for improving growth and yield of mung bean under saline conditions in a pot experiment. Mung bean seeds were inoculated with peat-based inoculum and NP fertilizers were applied at 30-60 kg ha-1, respectively. Results revealed that imposition of salinity reduced the growth and yield of mung bean. On the contrary, separate application of L-TRP and rhizobium appeared to mitigate the adverse effects of salt stress. However, their combined application produced more pronounced effects and increased the plant height (28.2%), number of nodules plant-1 (71.4%), plant biomass (61.2%), grain yield (65.3%) and grain nitrogen concentration (22.4%) compared with untreated control. The growth promotion effect might be due to higher auxin production in the rhizosphere and improved mineral uptake that reduced adverse effects of salinity. The results imply that supplementing rhizobium inoculation with L-TRP could be a useful approach for improving growth and yield of mung bean under salt stressed conditions.     

小麦/蚕豆间作作物生长曲线的模拟及种间互作分析

物种间的相互作用与间作产量优势的形成密切相关,但很少有人注意到种间互作动态.本研究通过2年田间定位试验,运用Logistic分析模拟了不同种植模式(小麦单作、蚕豆单作和小麦/蚕豆间作)和不同磷水平下[P₀,施磷量(P₂O₅)为0 kg·hm^-2(对照);P₁,施磷量(P₂O₅)为45 kg·hm^-2;P₂,施磷量(P₂O₅)为90 kg·hm^-2]单间作小麦、蚕豆的生长模型,分析了作物种间互作的动态变化.结果表明: 小麦/蚕豆间作使小麦产量提高了10.5%~18.6%,蚕豆产量却降低了4.8%~12.3%,但间作系统仍具有产量优势,土地当量比(LER)和相对拥挤系数(K)分别为1.01~1.15 和1.12~3.20.小麦和蚕豆的产量及关键生长参数均受磷水平调控,但LER和K并不受磷水平影响.与单作相比,间作小麦的最大生长速率(R_max)和最初生长速率(r)分别提高21.8%~38.7%和20.7%~38.9%,但间作对蚕豆的关键生长参数无影响.在小麦、蚕豆的生长初期,不同磷水平下,单间作作物的生长曲线无差异;间作群体以种间竞争为主,无间作生物量优势(LER<1,K<1).当蚕豆达到最大生长速率(T_max)后,间作显著提高了小麦的生长速率,降低了小麦的种内竞争压力,表现出间作生物量和产量优势(LER>1,K>1).总之,在不同的生长发育阶段,小麦、蚕豆的相互作用不同,间作提高了中后期小麦的生长速率,为间作优势的形成奠定了基础.     

Effect of intercrops on thrips species composition and population abundance on French beans in Kenya

The study aimed at determining thrips species composition and thrips population density on French bean planted as a sole crop and as an intercrop with either sunflower, Irish potato, or baby corn, in various combinations. Field experiments were conducted in two seasons to examine: (1) thrips population development and thrips species composition over time, (2) effect of intercrops on thrips population density and natural enemies, and (3) effect of intercrops on French bean yield. The experiments were conducted at the Kenya Agricultural Research Institute, Embu, Kenya in a randomized complete block design with four replicates. The thrips population on French beans increased with time. It showed a peak at the flowering stage then started declining when the crops were nearing senescence. French beans hosted four thrips species, Megalurothrips sjostedti (Trybom), Frankliniella schultzei (Trybom), Frankliniella occidentalis (Pergande), and Hydatothrips aldolfifriderici (Karny) (all Thysanoptera: Thripidae) in order of decreasing abundance. The main thrips species on Irish potato and sunflower was F. schultzei. Baby corn hosted only Frankliniella williamsi (Hood) and Thrips pusillus (Bagnall). A monocrop of French bean hosted more thrips than a French bean intercrop mix. Thrips natural enemies such as Orius spp. and Ceranisus spp. were recorded in all crop plants but in especially high numbers on French bean and baby corn, respectively. Plots with French bean alone had about 1.4 times higher yields compared to intercropped plots of French bean with sunflower and French bean with baby corn. However, the percentage of pods that could get rejected on the market due to thrips damage was highest on plots with French bean alone (68 and 63%) and lowest on plots with French bean and baby corn (35 and 37%) in the first and second seasons, respectively. This study showed that a complex of thrips is found in the field and its composition varies with crop stage and species. Intercropping French bean with other crops compromises on French bean yield but reduces damage to the French bean pods, thereby enhancing marketable yield.     

Drought-induced changes in chlorophyll fluorescence,photosynthetic pigments,and thylakoid membrane proteins of Vigna radiata

The effects of drought on chlorophyll fluorescence characteristics of PSII, photosynthetic pigments, thylakoid membrane protein (D1), and proline content in different varieties of mung bean plants were studied. Drought stress inhibits PSII activity and induces alterations in D1 protein. We observed a greater decline in the effective quantum yield of PSII, electron transport rate, and saturating photosynthetically active photon flux density (PPFD_sat) under drought stress in var. Anand than var. K-851 and var. RMG 268. This may possibly be due to either downregulation of photosynthesis or photoinhibition process. Withholding irrigation resulted in gradual diminution in total Chl content at Day 4 of stress. HPLC analysis revealed that the quantity of β-carotene in stressed plants was always higher reaching maxima at Day 4. Photoinactivation of PSII in var. Anand includes the loss of the D1 protein, probably from greater photosynthetic damage caused by drought stress than the other two varieties.     

THE PARASITISM OF STRIGA HERMONTHICA BENTH. ON LEGUMINOUS PLANTS

Pot experiments at the Gezira Research Farm showed that Striga hermonthica Benth. is not confined to the Gramineae but can also parasitize groundnuts, cowpea, dolichos bean and soya bean, causing a loss in yield in all but the last-named. The Striga plants developing on the roots of these hosts were small, apparently ill-nourished and did not grow more than 1 cm. above the ground, in contrast to the vigorous, flowering Striga plants that develop on sorghum. The greatest reduction in yield in these experiments was in dolichos bean, where the aerial growth was reduced 60%; no significant reduction in root weight was found in groundnuts, cowpea or soya bean. The last-named plant appeared to be feebly parasitized by S. hermonthica. A reduction in total nodule weight, but not in number of nodules, was obtained in groundnuts and cowpea. Parasitized dolichos bean showed a reduction in both the number of nodules and in nodule dry weight; in groundnuts, the later fruit production was seriously reduced.
The use of these leguminous crops to clean Striga -infested soil is discussed.     

供肥对小麦间作蚕豆群体产量及根系的调控

利用田间,池栽,盆栽等方法,对不同N,P水平下小麦间作蚕豆群体根系的时空分布及产量效应进行了研究。结果表明,供P对小麦-蚕豆间作系统有明显的增产作用,与不供P相比,田间试验中供P处理间作小麦和蚕豆分别提高了48.39%和16.69%,池栽试验中群体产量增产幅度为20.07%-43.14%。间作蚕豆经济产量增幅为58.46%-78.78%,小麦间作蚕豆多作系统2种作物根密度生长高峰期交错出现,小麦的峰值出现早于蚕豆,其中,小麦和蚕豆根干重最大值分别出现在抽穗期和成熟期,而根长的最大值分别出现在拔节期和成熟期,这在一定程度上减轻了共生期2种作物对水肥的竞争,也是此群体增产增效的原因之一,施P处理间作小麦的根重,根长和根表面积分别比不施P处理提高54.33%,48.88%和47.00%;施N处理间作小麦的根重,根长和根表面积分别比不施N的增加15.25%,11.61%和11.46%。间作小麦根重的57.61%和蚕豆的69.20%分布在0-30cm土层,随施P水平的提高,总根干重及根密度都趋于增加,且深层土壤中根系增加明显。