长枝木霉T6菌株对美洲南瓜枯萎病菌的抑制作用

为探明长枝木霉T6菌株对美洲南瓜枯萎病菌的作用机理，采用对峙培养、显微观察、孢子萌发、室内防效测定等方法研究其抑制能力和防治效果。结果表明：长枝木霉T6菌株对美洲南瓜枯萎病菌具有较强的抑制作用，对峙培养7 d时，长枝木霉T6菌株对该病菌的抑制率为60.09%；显微形态观察表明：长枝木霉T6菌株菌丝与美洲南瓜枯萎病菌菌丝发生缠绕；长枝木霉T6菌株发酵液对美洲南瓜枯萎病菌分生孢子萌发具有明显的抑制作用，抑制率为31.00%；长枝木霉T6菌株对美洲南瓜枯萎病具有较好的防治效果，室内盆栽防效为69.06%。     

栽培种南瓜的品种群研究

作者建议在葫芦科专家Whitaker划分的品种群(cultivar groups)分类基础上,按照果实形状及果形指数为主要指标,结合其他亲缘关系,将3个栽培种南瓜Cucurbita moschata,C.pepo,C.maxima划分成18个品种群,其中2个(C.pepo的观赏瓜品种群,C.maxima的板栗瓜品种群)是作者新划分的。     

Shading of plants facilitates selection for powdery mildew resistance in Squash

Summary Powdery mildew development was assessed on squash (Cucurbita pepo) plants of a susceptible cultivar, a resistant accession, their F₁, and their F₂ in an early summer planting in the field, covered or not covered with a shading net. Three reaction types were observed: susceptible, powdery mildew on stems and on both, the upper and lower leaf surfaces, as in the susceptible parent; resistant, no powdery mildew on leaves or stems, as in the resistant parent; and partially resistant, powdery mildew on upper leaf surfaces only, as in the F₁. Disease presence on the stem was associated with susceptibility. Shading hastened the appearance of powdery mildew and increased the severity of infection on partially resistant and susceptible plants, facilitating identification of resistant individuals in the F₂ population.Contribution No. 1613-E from the Agricultural Research Organization, Bet Dagan, Israel     

Seed Dimensions in the Subspecies and Cultivar-groups of Cucurbita pepo

Seed samples of 174 accessions of pumpkins, squash, and gourds of Cucurbita pepo were measured for length, width, and thickness. Mean seed length ranged from 8.8 to 23.3 mm, mean seed width from 5.0 to 12.5 mm and mean seed thickness from 1.2 to 3.8 mm. The seeds of the edible-fruited cultivar-groups of C. pepo subsp. pepo (Pumpkin, Vegetable Marrow, Cocozelle, Zucchini) were longer, wider, and thicker than those of their counterparts of C. pepo subsp. texana (Acorn, Crookneck, Scallop, Straightneck). The small-fruited, inedible gourds had the smallest seeds. Of the edible-fruited C. pepo subsp. pepo, the Pumpkin Group (round fruits) possessed the longest and flattest seeds whilst the Zucchini Group (long, uniformly cylindrical fruits) possessed the shortest and thickest seeds. The samples tested also differed greatly in mean values for relative dimensions. Length-to-width ratio ranged from 1.5 to 2.5, length-to-thickness ratio from 3.7 to 8.2, and width-to-thickness ratio from 2.0 to 4.9. The Pumpkin Group, followed by the Cocozelle Group (long, bulbous cylindrical fruits) and the Vegetable Marrow Group (short, tapered cylindrical fruits), had seeds of the highest length-to-width ratio. The seeds of the four edible-fruited groups of C. pepo subsp. pepo differed significantly from one another in their length-to-thickness and width-to-thickness ratios. The seeds of the Pumpkin Group and the wild Mexican gourd (C. pepo subsp. fraterna) differed greatly in their dimensions but were most similar to one another in their relative dimensions. In C. pepo, seed size is positively associated with fruit size and seed shape is inversely associated with fruit shape.     

菜田土壤有效氮的动态研究

在田间条件下研究了种植莴苣和西葫芦对菜田土壤硝态氮、有机态氮和微生物量氮剖面动态的影响 ,结果表明 ,不同作物对土壤表层硝态氮、有机态氮和微生物量氮影响较大 ,表层有效氮在作物生长期间基本上处于耗竭状态 ;2 0～ 4 0cm土层土壤有效氮除硝态氮以外 ,受作物影响较小 ;而 4 0～ 60cm土层土壤各种形态氮基本不受作物影响     

黑籽南瓜种子基质引发适宜条件研究

以黑籽南瓜种子为材料,研究了不同温度、处理时间和基质含水量对黑籽南瓜种子引发效果的影响。结果表明,基质引发处理能明显提高黑籽南瓜种子发芽势、发芽指数和活力指数,明显减少种子平均发芽天数;基质引发温度明显提高幼苗干鲜质量和根体积等,而基质湿度对幼苗生长性状影响不显著。黑籽南瓜种子基质引发处理以5℃、基质湿度65%时激发种子活力的效果最好,在不同基质引发温度和湿度条件下,改变引发持续时间所产生的效果是不一样的。     

不同种植密度对砍瓜产量的影响

进行了露地砍瓜栽培不同种植密度对砍瓜产量的影响试验。试验结果表明，采用1．5m×2m及1m×2m两种种植密度进行对比，1．5m×2m处理的产量、抗病性、产品外观和经济效益均比1m×2m处理有明显优势，其产量差异达显著水平，每1hm。增产18390kg，增产率达18．4％。综合衡量1．5m×2m种植密度为最佳的种植方式。     

低温弱光对西葫芦幼苗渗透调节物质的影响

以西葫芦品种早青一代为试材,研究了不同低温弱光组合及低温弱光持续时间对西葫芦幼苗渗透调节物质的影响。结果表明:可溶性蛋白质含量随低温弱光逆境程度加剧和持续时间延长持续减少;在15℃/5℃以上,弱光处理渗透调节物质游离脯氨酸、可溶性糖含量增加,但增加幅度随着弱光逆境加剧和持续时间延长而减弱;但在15℃/5℃下,弱光逆境导致游离脯氨酸、可溶性糖含量先增加后降低。     

金童观赏南瓜离体繁殖技术研究

通过消毒时间、外植体来源、激素组合等因素对观赏南瓜(金童)组织培养技术离体繁殖影响的研究,建立了其离体繁殖技术。试验结果表明:在利用子苗获得外植体过程中,南瓜种子用70%酒精表面消毒30 s,再用0.1%HgCl2溶液消毒10 min,可以获得最佳的消毒效果;在再生过程中,顶芽外植体的芽诱导率比子叶外植高;最佳诱导培养基组合为2/3 MS+6-BA 0.5 mg/L+3%蔗糖+0.7%琼脂。     

观赏南瓜子叶离体培养的初步研究

用‘京乐101’观赏南瓜子叶作外植体进行离体培养,初步建立了其离体组织培养的再生体系。结果表明,以MS为基本培养基诱导不定芽分化时,6-BA的附加是必须的,NAA的附加对诱导不定芽的分化有促进作用,GA3的附加虽未能提高不定芽的诱导率,但却能提高不定芽的诱导分化数,诱导不定芽分化的最佳培养基为MS 6-BA5．0mg/L NAA0．2mg/L CA30．5mg/L。同时在试验中发现,MS 6-BA2.0mg/L NAA0.2mg/L的培养基能从子叶块表面直接诱导出不定芽。不定芽在1／2MS NAA0．05mg/L 20g／L蔗糖的培养基上生根。