黑纹粉蝶在室外养虫网室中连续繁殖的滞育变化

系统观察了黑纹粉蝶PierismeleteMenetries在室外养虫网室中8个世代的滞育变化。结果表明：？夏季高温和长日照明显抑制了滞育的发生，在日平均气温为27℃的6月份，仅有15．9％的个体进入夏季滞育，在日平均气温29．5℃的7月份，夏季滞育则完全消失。！春季逐渐上升的日长（13h24min～14h21min）配合较温暖的气温（日平均19．1℃），诱导了99．6％的个体进入夏季滞育；秋后逐渐缩短的日长（11h53min～11h20min）配合较低的气温（日平均16．5℃），诱导了100％个体进入越冬滞育。秋季逐渐缩短的日长（14h12min～11h53min）配合较高的气温（日平均27．7℃）和较温暖的气温（日平均22．9℃和18．7℃），能满足大部分个体非滞育的发育。试验结果亦表明，黑纹粉蝶具有在夏季繁殖的潜在能力，虽然这种能力在自然条件下没有表现出来。文章最后讨论了该虫夏季带育诱导的光、温机制的适应意义。     

Determination of the genetic variation in the effect of temperature and daylength on bolting of Brassica campestris L.

Summary Effects of temperature and daylength on the bolting of a number of B. campestris accessions were investigated both in the open and in the IVT phytotron. From the results it was concluded that low temperature and genotype are the predominant factors with respect to bolting. Daylength has rather limited influence. One cultivar bolted more than 12 weeks earlier at 10 and 14°C than at 18°C. On the other hand some cultivars did not require vernalization at all.At 14°C and short daylength, depending on genotype, the period of time between sowing and 50% bolting ranged from 8 to 30 weeks. At this temperature the stimulating effect of long day (24 h), depending again on the genotype, ranged from 0 to 4 weeks. The genotypes most resistant to bolting appeared to be the stubble turnips (B. campestris ssp. rapa).In terms of seed(ling) vernalization at 5°C the cold requirement ranged from 0 to more than 3 weeks, depending on the genotype. The required vernalization periods at 5°C can be used as a criterion in screening for resistance to bolting.     

Improvement of durum wheat-plant type,yield potential,and adaptation

Summary Improvement of durum wheat at the International Maize and Wheat Improvement Center (CIMMYT) was achieved by exploiting the variability of the tetraploid species in large numbers of combinations, and multi-location testing of germplasm on a world wide base. High yielding, widely adapted durums with short straw, good fertility, and adequate earliness were selected for distribution to major durum growing countries. Present attempts to improve durum wheat are directed at adjusting agronomic traits such as leaf angle and straw strength, and increasing spike fertility and spike size, thereby reaching higher grain numbers per unit area and higher yield potential. Diversification of the developmental pattern and incorporation of drought tolerance aim at further widening adaptation.     

Variations in vernalization requirements among ecotypes of Festuca hallii

Plains rough fescue (Festuca hallii [Vasey] Piper) is an important forage grass species in the Northern Great Plains of Canada. Its seed is in demand for forage production and habitat restoration, but erratic seed production limits supply. A comprehensive understanding of factors influencing flowering and seed production in this species is needed. This study evaluated the morphological and phenological variation among six ecotypes of F. hallii from Saskatchewan and Manitoba. Seeds were germinated, and seedlings were grown in the field and then transplanted to a greenhouse in November. Plants not flowering in the greenhouse were vernalized under 5°C and 8-h light for 11 weeks. In a separate experiment, plants were subjected to temperature regimes of 15/5°C, 10/0°C and 5/−5°C with day-length treatments of 12 h, 8 h and a gradually changing daylength from 12 to 8 h respectively. This study demonstrated the existence of considerable variation in morphological and phenological characteristics, and in growth and vernalization requirements among ecotypes of F. hallii. Vernalization requirements were not met for the ecotype from the Moist Mixed Grassland Ecoregion when it was grown under common conditions, whereas ecotypes from other ecoregions were vernalized in at least one of the 2 years in the field experiment. Northern ecotypes tended to flower earlier after artificial vernalization treatments. Overall, 15/5 to 5/−5°C d per night temperature regimes with photoperiods between 12 and 8 h were effective in inducing flowering. The seed source of F. hallii should be regarded as an important consideration affecting its use, both for habitat restoration and for forage production.     

Influence of salinity, diurnal rhythm and daylength on feeding in Laternula marilina Reeve

A nature‐simulating culture system was used to explore the influence of salinity, the diurnal cycle and daylength on ingestion rate (IR) and assimilation efficiency (AE) of Laternula marilina. The clams used in the experiments were grouped into three sizes: large, medium and small according to shell length and dry fresh weight. The clams in all size groups demonstrated a common response pattern in IR and AE under salinities ranging from 18 to 34 g L^?1. The clams achieved the greatest IR within the salinity range 27–30 g L^?1. There was a marked reduction in IR outside this range. Of the salinities tested 18 g L^?1 was the harshest stress to the feeding of L. marilina. Between the salinities of 24 and 34 g L^?1, the AE of the clam responded in an inverse way to that of IR, suggesting that L. marilina is able to compensate for the loss of IR by an increase in AE. Although the differences between clam size groups were not statistically different, those between different salinities were except those between 27 and 34 g L^?1 (IR) and 23 and 34 g L^?1 (AE). All sizes of clam showed a two‐phase diurnal feeding pattern, a high ingestion phase from 00:00 to 08:00 hours and a low ingestion phase from 12:00 to 20:00 hours. The response of feeding (as measured by IR) to daylength comprised high and constant feeding at daylengths from 0 to 16 h and declining and unstable feeding as daylength increased from 16 to 24 h. All sizes of clams demonstrated an inverse adaptation to AE compared with IR, indicating that the clam is able to achieve a stable feeding physiology by compensating for daylength‐induced variations in IR by changing AE.     

Introgression of unique characteristics of floral initiation under 24 hour day-length of Fragaria chiloensis ‘CHI-24-1’ into F. × ananassa

A unique flower initiation of the wild Junebearing strawberry strain ‘CHI-24-1’ in Fragaria chiloensis occurs under 24 h DL and high temperature conditions. To introduce the floral initiation characteristics of ‘CHI-24-1’ into cultivated strawberries of F. × ananassa, a cross pollination was conducted between ‘CHI-24-1’ and the Japanese short-day type strawberry cultivar ‘Nyoho’. The floral initiation of ‘CHI-24-1’ was induced in both parent and daughter plants linked with runners under a 24 h DL and 23/20 ^∘C, but not 8 and 16 h DLs at the same temperatures. Of the 21 F1 hybrids grown under the 24 h DL, 12 showed flower truss production in the parent and/or daughter plants linked with runners. Among 64 F1 hybrids, 26 exposed to 8, 16 and 24 h DLs for 30 days produced no flower trusses. However, 32, one and five F1 hybrids produced flower trusses under the 24 h DL alone, 8 h DL alone and both the 8 and 24 h DLs, respectively. The results of the experiments indicated that none of the F1 hybrids were day-neutral plants, but approximately 60% had the characteristics of floral initiation under 24 h DL, which was inherited from the pollen parent of ‘CHI-24-1’. The importance of the unique floral initiation characteristics under 24 h DL with high temperature for strawberry breeding was discussed.     

大豆生态研究──XV．复式光温综合作用与中国不同进化型大豆生态类型的研究

根据２９３份不同进化型大豆原产地的自然临界光照和自然临界温度与公主岭自然温度下，１３．５ｈ光周期之间发生的复式光温综合作用原理以及生长发育规律，确定我国大豆生态类型。提出各纬度及同纬度不同海拔７４个县市的自然临界光照和自然临界温度。讨论了无野生大豆区光温综合作用与群落形成的关系以及研究光温综合作用理论的意义。     

Response to Daylength in Oats: Pre-Anthesis Development and Set of Spikelets and Florets

Daylength ranges between 15 h and 22 h when oats are sown in Finland. This study evaluated the effect of 15-h, 18-h and 24-h daylengths on apical development, pre-anthesis growth, and spikelet and floret set in two oat cultivars ( Avena sativa L.) adapted to northern growing conditions. Experiments were done in a growth chamber at 18°C.
Increases in daylength shortened the period of apical development. The oat cultivars were especially responsive to increase in daylength from 15 h to 18 h. The increase in daylength resulted in a 45 % reduction in number of fertile florets and a slight increase in the proportion of incompletely development and stunted florets. Fertility of florets was most reduced on the lower primary and secondary branches of the panicle. Total number of leaves and phyllochron decreased as daylength increased. Moreover, the longer the day, the lower the number of green leaves per main stem until developmental stage 11. However, at pollination, oats exposed to 15-h days had the lowest number of green leaves. Results of study indicated that delayed sowing, when associated with longer days at pre-anthesis, hastened apical development and decreased yield potential in oats.     

我国主要水稻光温敏核不育系类型的气候适应性

 针对夏季低温对我国两系杂交稻制种生产的严重威胁，用1997~1998年由三亚、武昌、贵阳、南京4个生态点组成的“新不育系联合生态鉴定”试验资料，分析了以培矮64S为代表的实用低温敏类型不育系和以N5088S为代表的实用光敏类型不育系的育性光温影响规律。结果表明，培矮64S的育性受温度影响，育性稳定性较差，下限温度指标年际间和地区间变化较大；N5088S育性主要受日长影响，其临界光长同一地年际间差异小，但地区间差异较大。同时，用1951~1992年逐日平均气温和理论日长资料，分析和评价了我国南方稻区（18°14′~34°17′N）的三亚、南京、广州、福州、长沙、杭州、南京、高邮、徐州等9个城市的光温特征及其时空规律。在此基础上，从生态角度提出了克服夏季低温危害两系杂交稻制种的三项生态技术措施，一是要根据气候规律正确选择适宜的制种地区和季节；二是华中双季稻区应改秋制为春制或选择山区单季稻区秋制；三是应全面评价温敏和光敏类型不育系的特点，因气候合理地利用现有的水稻不育系资源。     

Stolon characteristics and tuber initiation in a wild potato species (Solanum demissum Lindl.)

Summary Solanum demissum Lindl. is a short-day dependent, tuber-bearing species. In vitro propagated genetically identical plants were grown under long-day (16 h) conditions at 20°C day and 15°C night temperatures. Subsequently, from day 0 onwards, plants were exposed to shortday (10 h) conditions and grown in a multi-compartment system that allowed stolon initiation, stolon branching, stolon growth and tuber initiation to be monitored twice weekly. These frequent measurements resulted in detailed life-histories of all 841 stolon tips formed until day 46. Tuber initiation was irregular under these well-defined conditions; at day 46 only 106 stolon tips showed subapical swelling. This irregularity of tuber initiation was also observed within stolons. It is therefore suggested that tuber initiation depends on characteristics of the stolon or stolon branch, and several such characteristics were analyzed to obtain information on their potentially determining role in tuber initiation. No positive correlations were found between subapical swelling and branching order, stolon and stolon-branch age, longitudinal growth rates of stolons and stolon branches, and attachment of the stolon to the main stem.