白菜型油菜角果多室性状的遗传及解剖学研究

以白菜型多室油菜为材料，与3个不同来源的两室品种杂交，研究角果多室性状的遗传，并对多室油菜的子房发育进行了解剖学研究，结果表明，白菜型汪菜角果多室性状受1对隐性基因（mcmc)控制，不同发育时期的雌蕊子房横切切片观察发现，大部分多室油菜的子房在发育过程中形成三室，四室，部分子房发育为两室，表现嵌合现象，可能多室油菜在子房发育和角果形成过程中受环境因素的影响，致使假隔膜未能完全形成或中途退化     

Response of chickpea genotypes to low temperature stress during reproductive development

Low temperature at flowering is a major constraint to improved yield of chickpea in many regions of the world. In particular, cool dryland environments such as southern Australia, parts of the Indian sub-continent and the Mediterranean would benefit from cultivars with the ability to flower and set pods early in the growing season before soil moisture becomes a limiting factor. This paper demonstrates that low temperature (less than 15 °C) affects both the development and function of reproductive structures in the chickpea flower. Aspects of the male and the female gametophyte phases of development are described. Comparisons between chilling sensitive genotypes are made to identify the likely causes of flower abortion. The function of pollen derived from chilling sensitive plants is clearly affected most by low temperature stress, particularly the growth of the pollen tubes down the style before fertilisation occurs. In contrast, pollen tubes derived from chilling tolerant plants continue to grow down the style under low temperature stress. Although other stages of development and function were affected by low temperature, including sporogenesis, pollen germination, and the stigma, none were correlated to the phenotype of the mother plant. The implications of the findings for chickpea improvement programmes are discussed.     

Variability and regulation of the number of ovules, seeds and pods according to assimilate availability in winter oilseed rape (Brassica napus L.)

The number of pods per plant and the number of seeds per pod are the most variable yield components in winter oilseed rape (WOSR). Both the number of ovules per pod and the potential for the ovule to develop into a mature seed may depend on pod position in the plant architecture and time of appearance. The complex developmental pattern of WOSR makes it difficult to analyse. The objectives of this study were to investigate the variability of the following yield components (a) ovules/pod, (b) seeds/pod, and (c) pods/axis in relation to two explanatory variables. These two variables include (1) flower and inflorescence position and (2) time of pod appearance, linked to the effect of assimilate availability.Field experiments were conducted with the variety Mendel. Different trophic states were created by clipping the main stem or ramifications. The number and position of flowers that bloomed within the inflorescence were recorded based on observations every two to three days throughout the flowering season.On the control plants, for the main stem we observed that the number of ovules per pod decreased for a few ranks and then tended to increase and again to decrease at the end. On ramification R1 and R4, the number of ovules increased at first, and then remained constant with the pod rank. Furthermore, the number of ovules per pod remained constant along the inflorescence on the other ramifications and increased with ramifications from top to bottom. The number of seeds per pod did not vary with the pod rank at the basal positions on inflorescences and decreased afterwards along the inflorescence. The clipping of the main stem or ramifications increased the number of ovules per pod, seeds per pod and pods per axis. The number of ovules and seeds per pod did not vary with the time of pod appearance for the pods located at normalised rank 0.01-0.1. However, the number of ovules and seeds per pod can be impacted by the time of pod appearance on the plant scale. Thus, our results indicate that the amount of available assimilates was the primary determinant of pod and seed production during the flowering period. The distribution of resources was significantly affected by both the positions of pods within an inflorescence and the position of inflorescences within a plant.     

Effects of relative humidity and high temperature on spore germination and development of tomato powdery mildew (Leveillula taurica)

The effects of relative humidity (RH) and temperature on tomato powdery mildew (Leveillula taurica) were studied in controlled environments to define conditions that affect disease development in fresh market tomatoes in California. Gradients of RH (20–90%) at constant temperatures (20–30°C) were generated in single growth chambers to determine their effect on mildew development on mature tomato plants. Temperatures of 30°C and above were deleterious for spore germination, germ tube elongation, and disease development. Lesion growth and rate of disease progress were significantly higher at 20°C than at 25°C. Low RH levels (20–40%) reduced spore germination and lesion growth, accelerated host tissue death and reduced disease progress. Intermediate RH levels (50–70%) increased spore germination and optimized disease development, provided temperatures were maintained within favorable limits. High RH levels (80–90%) were favorable for spore germination but continued exposure to these conditions led to a limited lesion growth and disease progress. Short daily periods (two or three daily exposures of at least 2 h) of high temperatures (35°C) suppressed disease development by 70–92%.     

Causes of low seed set in white clover (Trifolium repens L.)

A field experiment was conducted to clarify the factors responsible for poor seed set in four white clover ( Trifolium repens L.) cultivars. Although the mean number of ovules per floret was 5·18–5·29, the average number of seeds per floret was found to be only 1·23-1·82. A stainclearing technique was used to examine the cytoplasmic state of the embryo sac in intact, unfertilized, mature ovules and it was found that 28–33% of ovules per carpel were sterile. The abortion rate of fertilized ovules and immature seeds (7 days after pollination) ranged between 32 and 34%. Beyond this period, it was observed that only a very small proportion of the total seeds were lost. The observation of high pollen fertility and a high pollen load strongly suggests that poor pollination does not account for the reduced number of seeds per floret. A 'nutrient competition' hypothesis was proposed for high ovule sterility and post-fertilization abortion of developing seeds.     

Growth of Trifolium repens L. and Trifolium semipilosum Fres. Var. glabrescens Gillet at different temperatures in controlled environments and in the field

The growth of Trifolium semipilosum Fres. var. glabrescens Gillet cultivar Safari, and Trifolium repens L., cultivars Haifa and Grasslands Huia was compared in controlled temperature glasshouses at 15/10, 21/16, 27/22 and 33/28°C (day/ night), and over eighteen months under four-weekly cutting in the field. In glasshouses, white clovers grew better than Safari at all temperatures except 27/22°C. Stolon production and partitioning of dry matter to stolons was greater, and petiole production and partitioning of dry matter to petioles was less for Safari than for white clovers. Haifa and Huia differed primarily in individual leaf weight, individual leaf area and leaf numbers; with Hula and Safari, but not Haifa, exhibiting a reduction in leaf size in response lo defoliation. In the field, growth of Safari was poor. Growth responses of Haifa and Huia in the field were related to seedling vigour, dry matter partitioning between leaves and stolons, and response to defoliation at low temperatures. It was concluded that there were major differences in growth, dry matter partitioning, morphology and response to temperature between T. semipilosum and T. repens. These differences particularly influence climate adaptation and competitive ability at the seedling stage.     

The effect of temperature and light during storage of young seed potatoes on initial plant development at early plantings

Summary Young seed tubers of several cultivars were exposed to storage temperatures of 4–24°C in light and dark intended to optimise their growth vigour following early plantings. In five experiments during four autumn and winter periods, the effects of storage conditions on subsequent initial plant development in the glasshouse were studied. Storage of seed potatoes for 2 months at temperatures of 12°C or higher greatly increased early plant development of five cultivars following early plantings. Light during storage had a favourable effect, but desprouting before planting was greatly disadvantageous.     

海南普通野生稻的花粉育性观察及杂交亲和性

对海南3个不同居群的普通野生稻(O.rufipogon Griff.)的花粉育性进行了观察研究,并采用荧光显微镜技术观察了转基因水稻花粉在不同居群的普通野生稻柱头上的萌发和在花柱内的生长过程。结果表明,以转基因水稻为对照,3个不同居群的野生稻相互之间花粉可育率在1%水平上差异极显著。用荧光显微镜观察时发现,转基因水稻花粉能在3个居群的普通野生稻的柱头上萌发并能到达胚珠,二者杂交亲和,同时发现,花粉管进入三亚居群胚珠的数目比儋州、万宁居群的数目多,说明相对于儋州、万宁居群来说,三亚居群与转基因水稻的杂交亲和性更高。     

Influence of daylength and temperature during formation of seed potatoes on subsequent growth and yields under long day conditions

Production of high quality seed potatoes is normally favoured by a cool climate with minor pest problems. Growth chamber studies aimed to reveal if daylengths (12 and 24 hrs) and temperatures (18/12 and 12/9°C day/night) during production also might influence progeny growth. Results showed no significant carry-over effect from daylength conditions, while growth vigour and yields were affected by parent plant growth temperature. Further experiments, including a greater range of temperatures, different cultivars and measurements of physiological age, are required to discuss theoretical and practical implications of the results.     

海南油茶不育株花器发育生物学特性及解剖学观察

从解剖学、细胞生物学及遗传学角度对海南油茶不育株花器发育过程导致不育的原因进行研究。以海南油茶正常株和不育株为实验材料,对其花芽发育过程外部形态特性进行阶段性比较观察,并应用花粉原位萌发技术检测其花粉萌发及花粉管发育差异;应用石蜡切片法对花芽分化过程中雌雄蕊进行解剖学观察,分析雌雄蕊发育时期与其花芽外部形态的相关性。结果表明：不育花与正常花外部形态上并无明显差异,但不育株开花后子房即脱落,表明没有正常授精,不育株柱头授粉后花粉粒不萌发,花粉管并不伸长;从雌雄蕊石蜡切片可以看出,不育株花器发育失常,其花药的绒毡层降解异常,无法形成成熟花粉粒,而在其胚珠发育过程中不育株未能形成成熟胚囊,导致空心胚珠。     

Soak conditions and temperature following sowing influence the response of maize (Zea mays L.) seeds to on-farm priming (pre-sowing seed soak)

On-farm seed priming of maize (i.e. soaking seed in water overnight, 17 h) in the semi-arid tropics has been shown to improve crop establishment and yield but the benefits can be variable. In previous work, this variation was thought to result from the interaction between primed seeds and conditions in the seedbed following sowing. To investigate this interaction, experiments were carried out under controlled temperature conditions that represented those of seedbeds in the semi-arid tropics. The conditions during seed priming and during subsequent germination and emergence were investigated as potential causes of variable seedling emergence relative to that of untreated seeds. Priming advanced emergence from moist sand cores at 30 °C/20 °C (day/night), reduced emergence at 35 °C/28 °C and delayed and reduced emergence at 40 °C/28 °C. In drier cores (drained 8 days) at 35 °C/28 °C, priming advanced germination time and did not decrease final percentage emergence. These results confirmed earlier field observations that the effect of priming in maize can vary and lead to positive, neutral or negative effects. Priming decreased the optimum and ceiling temperatures for germination, and unlike untreated seeds, the relationship between germination rate and sub-optimal temperature was not linear in all cases. Pre-humidifying seeds did not enhance the effect of priming, but aerating the soak water did. These results indicate that variable results from priming recorded in the field were not due to imbibitional damage, but may result from the negative effects of hypoxia during soaking exacerbated by moist conditions and high temperatures at sowing. These effects differed between seedlots of different cultivars, indicating the importance of selecting more tolerant maize hybrids to reduce variation in response to priming following sowing in the field. The implications of these findings for the use of primed seeds in the field are discussed.     

Survival of submerged larvae of cranberry girdler, Chrysoteuchia topiaria, in the laboratory

Flooding for several days in late summer or early fall is reported to control larvae of the cranberry girdler, Chrysoteuchia topiaria (Zeller) (Lepidoptera: Pyralidae), which feed on roots of cranberry, Vaccinium macrocarpon Aiton (Ericales: Ericaceae). During flooding, larvae float to the surface or remain submerged. Floating larvae are vulnerable to bird predation, but the fate of submerged larvae has not been studied. The factorially designed laboratory experiments reported here examined survival of submerged cranberry girdler larvae at water temperatures of 10, 15 or 20 °C, and flood durations of 24, 48 or 72 h. These conditions are characteristic of floods applied to western Canadian cranberry farms. In the first year of the study, more submerged larvae survived at 10 °C than at 15 or 20 °C, and more survived 24-h submersion than 48- or 72-h submersion; there was no difference between survival at 15 and 20 °C or 48- and 72-h submersion. In the second year of the study, when there were no 10 °C treatments, more submerged larvae survived at 15 than at 20 °C, and more survived 24-h submersion than 72-h submersion; survival after 48 h was not significantly different from survival after 24 or 72 h. In both years, there was no interaction effect of water temperature and duration of submersion: survival of submerged larvae decreased with longer flood durations and higher temperatures. Dissolved oxygen concentrations before submersion ranged from 5.8±0.1 to 6.3±0.2 ppm in the first year, and 5.5±0.1 to 5.7±0.1 ppm in the second. After submersion, dissolved oxygen concentrations in cups with larvae were approximately 0.5 ppm lower than in cups without larvae, suggesting that larvae continued to respire and use oxygen for some time after submersion. Results of the experiments are used to improve guidelines for flooding to control cranberry girdler larvae.     

Assessment of the physiological vigour of new potato cultivars in Switzerland

Summary Dormancy, incubation periods and physiological vigour or rusticity of new potato cultivars were determined during the official cultivar assessment programme in Switzerland. A total of 60 cultivars were assessed, including the standards, Sirtema (early), Bintje (mid-early) and Eba (mid-late); Russet Burbank was re-examined. Large variation between cultivars was observed, from 2000 to 3400 day-degrees for dormancy and from 1900 to 3700 day-degrees for incubation periods, expressed as sums of cumulated temperatures above zero centigrade. Field trials with physiologically aged seed identified the physiological vigour or rusticity of the cultivars. Those with low vigour or low rusticity showed poor emergence and yield after prolonged sprouting periods. The lowest produced less than 10% of the yield of seed of optimum physiological age stored under standard conditions. However, some high vigour or very rustic cultivars produced 100% of their potential yield. There was no relationship between earliness and physiological vigour. Vigour is very useful to farmers because it indicates those cultivars that are sensitive to warm storage or long sprouting periods and desprouting before planting. Dr Winiger passed away on 9th October 2000     

转基因水稻B2花粉活力的温度模型

 以含bar基因的抗Basta转基因粳稻B2为材料,分别在5℃、10℃、15℃、20℃、25℃、30℃、35℃、40℃、45℃下进行处理,用2,3,5-氯化三苯基四氮唑（TTC）染色法测定了不同温度处理下转基因水稻B2花粉离体0、1、2、3、4、5、6、8、12、14 min后的活力。B2花粉离体后活力呈现“S”型下降,用Logistic模型可精确模拟两者的关系; 其次, B2花粉离体后活力随着温度先升后降,花粉活力的最适温度范围是20℃~30℃,25℃时活力最强,高温对花粉活力的胁迫作用更大。采用指数方程和Logistic方程分段函数,建立B2花粉活力的温度模型,可精确预测花粉存活时间和寿命,为进一步准确估算转基因水稻基因飘移距离提供依据。     

水稻花粉萌发及花粉管生长动态

用显微镜观察水稻花粉粒的萌发、花粉管在雌蕊中的生长以及授粉后不同时间剪除柱头处理对颖花结实率的影响。 水稻花粉粒在授粉2 min后开始萌发;5～10 min后花粉管穿过柱头进入花柱生长;约经30 min花粉管顶端到达子房基部;40 min时有些花粉管顶端可接近胚囊,此时花粉管内胼胝质形成,但数量较少;50 min后花粉管内胼胝质塞大量形成,花粉粒萎缩干瘪。水稻花粉管在柱头、花柱和子房中的生长速率分别为1500、5000、5400 μm/h。水稻授粉后10～15 min剪除柱头的处理只有极少量颖花结实,授粉后20～50 min剪除柱头处理的颖花结实率随处理时间推迟而升高,授粉后50 min剪除柱头处理的结实率达60％以上,接近正常。     

Improved solarization of containerized medium for the control of Monosporascus collapse in melon

Melon collapse caused by the heat-tolerant soil-borne fungus Monosporascus cannonballus is not controlled by current solarization technology applied to large soil volumes because the temperatures achieved are not high enough to kill the pathogen's ascospores. The efficacy of improved solarization achieved by mulching a shallow layer of growth medium in containers was studied in terms of disease control and yield increase over two growing seasons. Compared to solarization of a regular container, solarization of a shallow layer (5–6 cm) of growth medium resulted in a 3–5°C elevation in maximal temperature at a depth of 3 cm, and in a 7–10°C increases at the bottom of the shallow layer. This led to a higher disease reduction and higher yields in the 1996 experiment. In 1997, both methods of solarization were highly effective. Yield was highly correlated with disease reduction in both experiments. In the 1997 experiment, ascospore viability declined faster in the shallow container treatment than in the regular container. This study demonstrates the potential of an additional approach for improving solarization of containerized plant growth medium and improving its reliability, with the aim of controlling heat-tolerant pathogens.     

澳系睡莲花粉离体萌发及低温保存研究

为研究适宜睡莲花粉离体萌发的培养基和低温保存的方法,以睡莲品种‘默笙’和3份原种睡莲的花粉为试验材料,采用单因素、正交试验设计,筛选出最适宜的培养基,观测睡莲花粉在不同温度下保存的萌发率。结果表明,4种澳系睡莲花粉的最适培养基的各组分浓度不同,花粉的生活力存在差异,澳洲原生浅色睡莲与澳洲原生深色睡莲的花粉生活力较高,分别为43.90%和45.63%;‘默笙’睡莲的花粉生活力次之,为31.84%;‘白巨睡莲’的花粉生活力较低,为9.73%;4种澳系睡莲花粉均不耐贮藏,不同温度下保存72 h后萌发率均为0。本研究结果可为睡莲杂交育种的亲本选择、花粉的低温保存研究提供参考。     

Pollen Grain Germination and Pollen Tube Growth in Pistil of Rice

The germination of pollen grain in vitro and the growth of pollen tube in the pistil of rice were observed with a microscope. The stigma was removed at different time points after pollination to study its effect on seed setting rate. The rice pollen grain started to germinate at 2 min after pollination and the pollen tube penetrated stigma into style in 5–10 min, 30 min later the end of pollen tube reached the bottom of ovary, and only some pollen tubes arrived at embryo sac at 40 min after pollination. Mea...     

Pod Dehiscence in Soybean : Assessing Methods and Varietal Difference

Abstract

The varietal difference of pod dehiscence in 25 soybean cultivars consisting of 16 Japanese and 9 Thai cultivars was examined at 3, 5, 7, 14, 21, 28 and 35 days after placing in a desiccator (desiccator method) and 2, 4 and 7 hrs after placing in an oven at 60ºC (oven-dried method). The cultivars examined were divided into susceptible and resistant groups according to the degree of pod dehiscence. Most of the Japanese cultivars (excepting Suzuotome) and NS1 were susceptible while most of the Thai cultivars (excepting NS1) and Suzuotome were resistant to dehiscence. The degrees of pod dehiscence measured by the desiccator and oven-dried methods were nearly the same, and the moisture content of the pods not dehisced was always higher than that of the dehisced pod. The effect of ambient humidity on pod dehiscence was examined in five soybean cultivars SJ5, Shirotae, Tamahomare, CM60 and Fukuyutaka. When the pods were exposed to 15 or 25% relative humidity (RH), the pods of susceptible cultivars, Shirotae, Tamahomare and Fukuyutaka, started to dehisce at 24 hrs after the start of the treatment, but those of resistant cultivars, SJ5 and CM60, did not dehisce for 72 hrs. None of the cultivars dehisced under 50 and 60% RH. These results revealed that placing the pods in the desiccator for 14 days (desiccator method) or exposing the pods to 60ºC for 7 hrs in an oven (oven-dried method) were useful methods for checking the degree of dehiscence.     

影响甘蓝型油菜每角粒数因素分析

为培育高角粒数的油菜品种，研究每角粒数种子（或胚珠）败育对每角果粒数的影响，选取36份双单倍体（DH）材料，采用自然开放和强制自交、杂交、辅助人工授粉等4种处理方式，分别调查各处理中初花时胚珠数和成熟风干角果中正常成熟籽粒和败育种子的数量与形态变化，探寻种子（或胚珠）败育发生原因。结果发现：材料的初始胚珠数为23.05~36.15个，差异极显著。种子成熟后，每角粒数为平均16.80；胚珠数与每角粒数间的相关系数为0.77**；各材料每角粒数占初始胚珠数的百分比为平均56.19%，近44.00%的胚珠在种子发育过程中会发生败育；胚珠数与每角粒数呈正相关；败育是导致每角粒数减少的主要原因。不同材料胚珠数不同，胚珠数与材料基因型有关，败育比率也与材料基因型有关。根据胚珠的直径可将败育类型划分为3种：a类型（直径小于0.1mm）、b类型（直径0.1~1.0mm）、c类型(胚败育)。3种败育类型在36个参试材料和4种试验处理中均有发生，前两种类型败育是胚珠（或种子）败育的主要类型，平均发生概率分别为19.34%和7.91%，胚败育发生概率较低，仅为1.54%。胚珠（或种子）败育现象普遍存在于甘蓝型油菜种子发育过程中，原因可能与花粉和柱头发育、花粉与柱头识别、受精以及胚初期发育异常相关；胚败育可能与胚发育停滞有关。