本试验结果表明:从吉林省农业科学院引进的玉米杂交种四单19在西藏林芝和拉萨均可种植,其经济产量和生物产量均较高;在西藏林芝首次进行四单19(吉444×Mo17)玉米杂交种繁育制种试验,初步取得了成功,在933 m2土地上生产出95.2 kg杂交种和74.2 kg父本自交系。

本试验结果表明:从吉林省农业科学院引进的玉米杂交种四单19在西藏林芝和拉萨均可种植,其经济产量和生物产量均较高;在西藏林芝首次进行四单19(吉444×Mo17)玉米杂交种繁育制种试验,初步取得了成功,在933 m²土地上生产出95.2 kg杂交种和74.2 kg父本自交系。     

海湾扇贝自交家系的建立和自交效应

以1992年12月从加拿大引种到中国、以群体交配的方式在中国繁养了7代的海湾扇贝(Argopecten irradians)为材料，随机选取15个性腺发育成熟的个体，分为A、B、C3组，分别通过自体受精建立15个自交家系，每组设各自混群对照。结果表明，海湾扇贝自体交配家系的受精率较高，并与对照组相近；但孵化率变化较大，15个自交系的孵化率变化范围为1．35％～68．23％，平均为31．44％。自交家系F。面盘幼虫的生长速率明显低于对照组，附着变态时间也迟于对照。在15个自交家系中有14个获得成体子代，共1311个个体，但各家系间差异很大，从13个到186个不等。自交家系子代个体可以发育到性成熟并可繁殖F2，证明通过自交培育海湾扇贝家系在技术上可行。方差分析表明，除A组自交家系体重与其对照差异不显著(P≥0．05)外，其余绝大多数自交家系和对照组相比，在壳长、壳高和体重方面的差异显著(P≤0．05)或极显著(P≤0．01)。本研究还表明，海湾扇贝的自交可导致自交衰退，表现为发育迟缓和个体小型化。在面盘幼虫阶段自交衰退率为25．9％，成体阶段平均为12．7％。     

温度对白魔芋花粉功能及自交结实的影响

研究温度对白魔芋散粉、花粉萌发、活力保持及自交结实的影响,以离体萌发法测定花粉萌发率,以培养箱法测定恒温自交结实率,以野外套袋法测定自然自交结实率。结果显示:最佳散粉温度22~26℃,18℃低温下可正常散粉,而34~38℃高温下80%以上花株花粉囊无法正常开裂;高浓度钙可加快花粉管的生长;花粉在18、22、26、30、34、38℃下的萌发率分别为8.78%、33.17%、54.90%、38.83%、29.10%、6.98%;花粉在38、34、30、26、22、18℃贮藏下分别在4、4、12、12、25、55 h内丧失活性。恒温培养中仅26℃下有4.35%的自交存活率,野外套袋中日平均温度为23.7℃时有2.94%的自交存活率。白魔芋的散粉培养及离体萌发最佳温度为26℃,温度过高或过低均影响授粉结实率。及时采集花粉、控制温度、调节湿度、适当灌溉均能提高授粉结实率。     

Reduction of pollen contamination in Scots pine seed orchard crop by tent isolation

This study examined the differences in mating system between indoor versus outdoor Scots pine (Pinus sylvestris L.) seed orchard using DNA markers. By analyzing the paternities in seed crops from isolation tents, we found a significant reduction in contamination rate, from 23% in the outdoor open blocks to 0% inside the tents. Increase in selfing rate and a decrease in genetic diversity in the crops were also observed inside the tents. These undesirable effects can be mitigated to some extent by the supplementation of extra pollen genotypes, e.g. selfing rate decreased from 14.4% to 6.6% and the effective number of fathers increased from 6 to 11.4 in the tents without and with supplemental mass pollination, respectively. Our study showed that tent isolation may become an effective rescuer for seed orchards where pollen contamination is severe.     

‘Thermally aided pollination’: A new method of breaking self-incompatibility in Brassica oleracea L.

Summary Application of heat during self-pollination of open flowers by means of an electric mini soldering iron resulted in seed set in self-incompatible Brassica oleracea varieties. Temperatures of 60, 70 and 80°C were tested. Compared with bud-pollination, in some cases the so-called thermally aided pollination (TAP) method, gave a considerably higher seed yield at 70 and 80°C. In view of the ease and rapidity of TAP it should be ascertained how far this method can replace bud-pollination in maintaining inbred lines. The possible mechanism behind the TAP response is briefly discussed.     

Breeding system and its consequence on fruit set of a rare sand dune shrub Eremosparton songoricum(Fabaceae:Papilionoideae):implications for conservation

The breeding system and its consequence on fruit set of Eremosparton songoricum(Litv.) Vass.,a rare shrubby legume occurring in moving or semi-fixed sand dunes of Central Asian deserts,were examined by manipulative experiments and observational studies in natural populations during the period of 2007-2009.The results showed that E.songoricum exhibits a mixed mating system.It is self-compatible,but depends strictly on pollinators to set fruits.Only two effective pollinators were detected and they triggered the specialized pollination mechanism(a 'brush type' and 'tripping mechanism').Geitonogamy becomes predominant in natural populations,because(74.5±1.3)% of visiting activity happened within or between inflorescences and(24.3±1.4)% occurred between ramets.As a result,inbreeding depression caused by geitonogamous selfing inevitably happened under natural conditions,showing 2.36 times less fruit set than was achieved by hand cross-pollination.The results explained the rarity of the species due to its breeding system,and will assist to develop suitable conservation strategies in severe desert environments.     

Genetics of a high-selfing trait in pigeonpea

Summary A true-breeding line characterized by free filaments of anthers and modified keel petal was derived from F₂ population of an intergeneric cross between Cajanus cajan (L.) Millsp. and Atylosia lineata W. & A. This variant, designated as partial cleistogamy, favours a high level of self-fertilization. The inheritance of this trait was studied in the F₁, F₂, F₃, and BC₁F₁ generations of three crosses. The results suggest that the partial cleistogamy trait is governed by a single recessive gene, designated as pct.     

海湾扇贝杂交家系与自交家系生长和存活的比较

2002年春季,利用国内现有的海湾扇贝两个不同遗传背景的养殖群体A和B的种贝为材料,采用自体受精和异体受精两种交配策略,建立了海湾扇贝的自交系和杂交系。实验由AA(A♀×A♂)、BB(B♀×B♂)、AB(A♀×B♂)、BA(B♀×A♂)四个组组成。杂交使两个表型性状———生长和存活都得到了改良。就生长而言,杂交组比自交组快,杂种优势在幼虫期为35.34%、养成阶段为21.17%;杂交组AB的生长速度比自交组AA的提高了35.53%(幼虫期)和43.32%(养成阶段),杂交组BA的生长速度比自交组BB的提高了35.13%(幼虫期)和12.34%(养成阶段)。就存活而言,两个杂交组的存活率都高于相应的自交组,杂种优势的平均值在幼虫期为19.93%,养成阶段为31.46%;杂交组AB的存活率比自交组AA的提高了25.23%(幼虫期)和49.44%(养成阶段),杂交组BA的存活率比自交组BB的提高了12.36%(幼虫期)和21.29%(养成阶段)。A、B两个群体间存在的遗传差异是它们能够获得杂种优势和性状得到改良的基础。