Light and temperature action in germination of seeds of the empress tree (Paulownia tomentosa)

Seeds of the empress tree ( Paulownia tomentosa Steud.) were imbibed for two weeks in darkness at constant temperatures (18, 23 or 28°C), and then irradiated with red light for 5 min. Germination was poor if it took place at the same temperature as imbibition, but a high percentage was achieved if the seeds were exposed to higher or lower temperatures before they were irradiated. Maximum germination was obtained when the difference between pretreatment and imbibition was about 10°C. The effect increased with the duration of the pretreatment and was optimal at 24 h. The effect decreased as the time lapse between temperature pretreatment and red light irradiation increased, and it was lost after two days. If pretreatment was shorter than 24 h (12 h). a high percent of germination was obtained by alternating pretreatment and imbibition temperatures. The germination of seeds imbibed in 40% heavy water was also stimulated by temperature pretreatments. Light and temperature also exhibited an interactive effect in the germination of seeds that were imbibed in darkness for only 3 days. For each of the germination phases there was a temperature at which the time needed for 50% germination was the shortest, namely 35°C during imbibition, 37.5°C in the period of P_fr activity. and 32.5°C during radicle protrusion. The data obtained are shortly discussed in relation to the domestication of empress tree in Southern Europe.     

农桐复合系统林带结构优化模式的研究

以麦桐复合经营为例,研究了林带的不同配置结构、林带覆盖率与小麦产量之间的关系,并通过一系列数学方法实现了林带结构的优化．结果表明,在一个轮伐期内,泡桐林带覆盖率累计均值为１０．１％～１０．９％时,小麦相对产量累计均值最大（１０５．４）,为最优林带覆盖率累计均值．最优林带距（Ｄ）与轮伐期（Ｔ）之间的关系为：Ｄ＝０．６００＋１１．０４２Ｔ－０．７８７Ｔ２＋０．０２７３Ｔ３（Ｒ２＝９９．９％）．     

兰考泡桐生物量积累规律的定量研究

对农桐复合经营兰考泡桐的干物质生产、积累和归还规律的系统研究表明,兰考泡桐生物量随树龄增大而增加,生物量在各器官的分配比例依次为：树干＞树枝＞树根＞树叶＞花;兰考泡桐年干物质生产主要集中在５～７月,占全年干物质生产总量的７７．３％;兰考泡桐凋落物绝大部分为落叶,占凋落物总量的８７．１％,凋落伴随年生长季节的全过程,且每年出现两次高峰;兰考泡桐干物质积累主要发生在５～７月,占全年干物质积累总量的７２．７％;兰考泡桐全生育期的干物质归还率为３３．７３％．     

泡桐微茎尖培养脱除泡桐丛枝病原（MLO）的研究

以感染丛枝病原（ＭＬＯ）的泡桐组培苗为试材,大量切取长度在０．３ｍｍ～０．５ｍｍ范围内的微茎尖,在ＭＳ和附加０．１ｍｇ／ＬＩＢＡ和１～７ｍｇ／Ｌ６－ＢＡ的培养基上进行脱毒试验。根据外植体培养过程的病状有无．病源ＭＬＯ的ＤＡＰＩ荧光显微镜和电子显微镜检查结果,证明微茎炎培养能够获得脱除泡桐丛枝病原ＭＬＯ的试管苗,其脱毒率在１４．２９～２８．５７％之间。脱毒的两个无性系试管苗经连续继代培养一年以上,其生长性状正常且稳定。试验还显示了微茎炎培养脱毒率受采用的茎尖大小、切割技术、培养基中的激素比例及无性系的不同等因素的影响较大。     

毛泡桐同源四倍体的诱导

在含有不同浓度秋水仙素双层培养基上以叶片作外植体诱导毛泡桐同源四倍体植株,用变异植株根尖细胞染色体计数和成熟叶片中单细胞DNA含量测定的方法进行倍性分析。结果表明,在16个试验组合中,预培养6d的毛泡桐叶片经20mg·L-1秋水仙素处理72h的四倍体诱导率可达20%。     

安徽涡阳县桐农间作类型及其效益分析

一、概况涡阳县位于黄淮平原南部,安徽省的西北部。全县土地面积2.09×10~5ha,其中耕地面积1.44×10~5ha。人口105万。本县属暖温带半湿润季风气候区,年平均气温14.6℃,降水量824mm,蒸发量1974.5mm。太阳辐射总量5.22×10~5J·m~(-2)。气候温和,水热同季,     

不同种源白花泡桐种子的休眠生理生态研究

为了探讨亚热带树木休眠理论以及休眠与树木分布的相互关系,研究了不同种源白花泡桐种子的休眠生理生态学特性。结果表明：白花泡桐种子适宜发芽温度范围在20～30℃,经过低温处理后,适宜发芽温度范围扩大到15～30℃,具有浅低温休眠特性;5℃的低温处理不仅提高了不同种源白花泡桐种子的发芽率和发芽势,而且加快了发芽速度,尤其在15℃发芽温度条件下的促进效果更加明显;40d的5℃低温处理效果最好．20d、60d的低温处理效果相对较差;没有用低温处理的不同种源白花泡桐种子,除了在25℃发芽温度下的发芽势差异不显著外,在不同发芽温度条件下的发芽率与发芽势都存在着显著差异,但在20℃、25℃发芽温度下的平均发芽时间差异不显著。在15℃发芽温度条件下,除了桂林种源以外,没有用低温处理的白花泡桐种子的发芽率与发芽势都随着种源纬度的增加而增加,而在20～30℃的适宜发芽温度范围内随种源纬度的变化趋势不明显;不同种源白花泡桐种子对低温处理反应差异明显。低温处理后的中亚热带以南的低纬度种源白花泡桐种子发芽率、发芽势都较北亚热带的高纬度种源高。低温处理后的中亚热带株州种源和北亚热带南部的宜昌种源白花泡桐种子的平均发芽时间最长,而随着纬度的降低或增加平均发芽时间都变短。不同种源白花泡桐种子的浅休眠特性不同,是对不同种源地气候的一种生理生态适应。     

Molecular evidence for the hybrid origin of Paulownia Taiwaniana based on RAPD markers and RFLP of chloroplast DNA

Genomic DNA of Paulownia fortunei, P. kawakamii and P. taiwaniana were amplified with 10-base primers of arbitrary sequences using the polymerase chain reaction (PCR). A total of 351 DNA fragments were amplified from 23 primers and of these 265 fragments (75.5%) were polymorphic. Almost all of the PCR-amplified products of P. taiwaniana were shared by either P. fortunei or P. kawakamii, or both, and the number of polymorphic fragments shared by P. taiwaniana and P. fortunei was about equivalent to those shared by P. taiwaniana and P. kawakamii. Restriction fragments of chloroplast DNA (cpDNA) purified from Paulownia species and from reciprocal crosses between P. fortunei and P. kawakamii were analyzed. Restriction enzyme SalI-digested cpDNA showed an identical pattern in both P. kawakamii and P. taiwaniana. These results further support the hypothesis that P. taiwaniana is the natural hybrid between P. fortunei and P. kawakamii and that the maternal parent of P. taiwaniana is P. kawakamii.This work was supported in part by the National Science Council (NSC-80-0409-B-054-06), Republic of China     

光周期对泡桐叶片体外植株再生影响研究

以毛泡桐、兰考泡桐和白花泡桐叶片为外植体,在其体外器官直接再生的最适MS和1/2MS培养基上,研究了不同光周期对泡桐叶片体外植株再生的影响.结果表明,光照时间为24 h的光周期可促进泡桐叶片芽的诱导,但不同种泡桐叶片芽诱导率达到最大所需时间存在一定差异.对幼芽根诱导来说,不同光周期对3种泡桐幼芽生根的作用存在差异.当幼芽诱导根时间为7 d时,光照时间长于或短于16 h的光周期都会抑制毛泡桐和兰考泡桐幼芽根的诱导,并且这些不适宜的光周期对白花泡桐和毛泡桐幼芽生根的抑制作用大于兰考泡桐.