土传大豆、南瓜疫病化学防治

本文介绍了土传大豆和南瓜疫病的发病特点及化学防治现状，评述了两种疫病化学防治存在的问题，提出了未来化学防治发展途径。     

Monosomic addition lines of Beta corolliflora in sugar beet: plant morphology and leaf spot resistance

Monosomic addition lines in Beta vulgaris from Beta corolliflora were described morphologically and characterized for disease resistance. Monosomic addition plants (2n= 19) were selected among segregating offspring by a squash dot technique in combination with B. corolliflora‐specific probes. Plants carrying an added chromosome were characterized by leaf shape, plant size and plant vigour. In this way, most addition lines could be distinguished from diploid beets, however, to identify those plants unequivocally, molecular marker analysis was also necessary. Transmission frequencies of each addition line were determined to be in the range 13.9% (Cor‐4) to 60% (Cor‐9). High transmission rate of addition line Cor‐9 was assumed to be due to apomictic propagation because transmission rate after selfing cannot exceed 50%. Cercospora leaf spot resistance tests were performed on 167 monosomic plants from seven different addition lines, two fragment addition lines and 89 diploid controls. No line exhibited complete resistance, but the monosomic additions Cor‐3 and Cor‐4 showed significantly lower infection rates than their diploid sibling plants. The identification of monosomic addition lines with apomictic and disease resistance characters offers the possibility of transferring those genes to sugar beet.     

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     

Genetic control of irregular striping, a new phenotype in Cucurbita pepo

Longitudinal striping of the fruit exterioris a common trait in Cucurbita pepo(pumpkin, squash, gourd). Striping occursas ten pairs of alternating dark and lightstripes that are regularly situated inaccordance with the ten sub-epidermalcarpellary vein tracts. Usually, the darkstripes occur in the central areas betweenthe vein tracts, with the light stripesoccupying the remainder of the fruitsurface. A new phenotype is described inwhich dark spots or streaks occur in thecentral areas between the vein tracts;these are usually accompanied by darkstreaks or stripes that occur adjacent toand over part or all of the length of someor all of the ten carpellary vein tracts. The inheritance of this irregular stripingpattern was studied by crossing anaccession that bred true for this phenotypewith a near-isogenic line havinglight-colored fruits. The resultsindicated that irregular striping isdominant to light coloration and isconferred by a single gene. Testcrossesfor allelism with regular striping wereprepared by crossing the irregularlystriped accession with near-isogenic lineshaving broad stripes, l-1 ^BSt/l-1 ^BSt, and narrowstripes, l-1 ^St/l-1 ^St. The testcross results revealed thatirregular striping is conferred by anallele at the l-1 locus, designatedl-1 ^iSt. The l-1 ^iStallele is dominant to light-colored (l-1), recessive to dark-colored (L-1), and can be co-dominant or recessiveto broad-striped (l-1 ^BSt) andnarrow-striped (l-1 ^St),depending on whether or not it is fullyexpressed. Dominance relationships at thel-1 locus can, therefore, berepresented as L-1 > (l-1 ^BSt > l-1 ^St) l-1 ^iSt > l-1.     

果肉型蓝莓饮料的研制

以蓝莓为主要原料,甜味剂、酸味剂,稳定剂等为辅料,采用正交实验设计,确定果肉型蓝莓饮料的最佳配比。实验结果表明,果肉型蓝莓饮料的最佳配方为：果汁200mL;糖度10Brix％;柠檬酸0．06％;苹果酸0．06％;CMC-Na0．20％、黄原胶0．06％、卡拉胶0．06％;均质压力：25MPa;杀菌条件：90～100℃,10min。最终产品口感细腻,质地均匀,具有天然蓝莓特有的香气,酸甜可口,适合各类人群。     

壳聚糖涂膜对低温贮藏西葫芦生理生化变化的影响

以壳聚糖作为涂膜保鲜材料,研究对12℃下贮藏的西葫芦主要生理生化特性的影响。试验结果表明:采用0.75%壳聚糖涂膜处理西葫芦,可以显著降低果实的失重率,抑制采后呼吸强度和细胞膜透性的升高,较好地保持西葫芦果实中可溶性固形物及果皮叶绿素的含量,使贮藏期间西葫芦果实内的过氧化氢酶维持较高水平,达到良好的贮藏效果。     

印度南瓜主要农艺性状与产量的通径分析

以印度南瓜品种为材料，对其主要农艺性状进行相关性和通径分析，结果表明，影响印度南瓜产量的主要决定因素是单瓜量和单株结瓜数。因此，在南瓜丰产育种中，应以单瓜重和单株结瓜数作为主要选择指标，同时，还应注意两者之间的相互协调。     

优质板栗南瓜新组合江红1号的选育

江红1号南瓜是由一个日本引进材料的分离后代中选出的自交系J－9559和一个台湾引进材料的分离后代中选出的自交系T－9662配制成的早熟印度南瓜一代杂种，与黄狼南瓜比较，第1雌花节位低4－5节，成熟期早15d，干物质含量高7．6％，总糖含量高5．3％，淀粉含量高2．2％，Vc含量高187mg/kg，江红1号为长蔓类型，生长势较强，瓜扁圆形，瓜皮红色，瓜肉桔黄色，肉质细密，粉质重，口感甜面 露地栽培，单位面积产量（u)667m^2为1500－2000kg。     

盐胁迫对西葫芦叶片光合性能的影响

以2个耐盐性不同的西葫芦品种白美西葫芦(盐敏感)和黑皮西葫芦(耐盐)为材料,用不同浓度的NaCl溶液进行处理,研究盐胁迫对西葫芦叶片光合性能的影响。结果表明,盐胁迫条件下,净光合速率(Pn)、叶绿素a(Chla)含量、叶绿素b(Chlb)含量随着盐胁迫浓度的增加和时间的延长总体上呈现下降趋势,而气孔导度(Gs)和胞间CO2浓度(Ci)总体上呈现先下降后上升的趋势,叶片Chlb/Chla比值随盐胁迫时间的延长逐渐升高。耐盐性不同的品种所受到的伤害程度不同,耐盐性强的品种黑皮西葫芦的伤害程度小于耐盐性弱的品种白美西葫芦。     

西葫芦未受精胚珠离体培养条件的优化及胚囊植株的产生

 【目的】建立西葫芦离体雌核发育高频植株再生体系，以加速自交系选育，有效缩短西葫芦杂种一代育种周期。【方法】将西葫芦未受精胚珠接种至附加2，4-D、NAA、BA的N6培养基上可形成胚状体，该胚状体转接至无激素的N6培养基上可形成再生植株。【结果】试验共获得120棵再生植株（R0），其中41株因生活力低下死亡，8株用于摸索移栽方法死亡，71株移栽成活且生长正常，其中42株性状表现符合二倍体特征且育性正常，已有10株获得自交果实及种子，其余29株育性异常。试验结果表明，胚珠发育时期、培养基、供体基因型及供体栽培季节等均显著影响胚状体诱导频率。【结论】胚状体起源于胚囊成员细胞，再生植株为胚囊植株。试验筛选出3种诱导频率较高的培养基；以开花前1日及当日的胚珠诱导频率较高；秋播材料诱导效果最好。