濒危植物银杉的结实特性及动物对果实的危害性

银杉结实量的年际波动很大,具有明显的大小年之分,一般在２～３个小年之后为１～２个大年。银杉母株的结实量在不同的母树间差别很大,平均单株的球果数仅为６６个。球果结实量在树冠南北侧有差异,南侧球果数占球果总数的６０％;球果结实量的垂直分异明显,树冠中、上部的球果数占总量的９０％以上。松鼠对树上尚未完全成熟的银杉果实的取食危害是长期性的,对银杉种子种群造成严重破坏。以１９９５年为例,被啃食的球果数占球果总数的比重可达１５％左右。试验表明,土壤种子库中地表的银杉种子几乎全部被动物取食,种子埋藏深度增加有利于逃避动物的取食。     

Distribution and phenology of climbers of Kumaun in Central Himalaya,India

A total of 105 climber species were recorded and studied for their altitudinal distribution and phenology. Relatively higher percentage (54%) of deciduous species was recorded. In general, the climbers were distributed throughout the region between altitudes of 300–3500 m. However, maximum (more than 60%) species were confined either below or at around 1500 m altitude. Species richness declines gradually towards the higher altitudes, the decline was more sharp in evergreen species. The different phenological activities were usually governed by the seasonal variations in a year. Seasonality of flowering suggested the prevalence of insect pollination. Whereas, fruit types indicated equal sharing of biotic and abiotic dispersal. Study concludes, the distribution and nature of various climber species of Kumaun in Indian Central Himalaya, depends largely upon altitude and its climatic variable temperature. Whereas, the seasonality of rains plays an important role in seasonal progression of phenophases.     

Control of basidiospore production by a nuclear gene in the fungus Coprinus congregatus

Summary The genetical control of basidiospore production by sporophores of the fungus Coprinus congregatus was studied. This species is characterized by a bipolar compatibility control, and homokaryons with complementary alleles A1 and A2 can be distinguished apart. We confirmed that the pale mushroom phenotype of the fungus is determined by a nuclear gene symbolized pal. This gene also controls a sporeless character and segregates independently of the mating-type locus. Dikaryons homoallelic for the pal ^– allele produce typical pale and sporeless sporophores, while heteroallelic (pal ⁺, pal ^–) and homoallelic (pal ⁺, pal ⁺) dikaryons produce normal or almost normal sporulating sporophores. In order to segregate homokaryons homoallelic for the pal gene (A1, pal ^–; A1, pal ⁺, A2, pal ^–; A2, pal ⁺), the following protocols were used: (a) the dikaryotization of stock homokaryons containing the pal ⁺ allele and of each mating type, A1 or A2, by dikaryotic mycelia homoallelic for the pal ^– allele; (b) the culturing of homokaryotic mycelia issuing from the germination of basidiospores from sporophores produced by dikaryotic mycelia heterokaryotic for the pal gene; (c) the culturing of mycelia grown from protoplasts obtained from dikaryons homoallelic for the pal ^– allele (D6 strain), and from homokaryons heteroallelic for the pal gene (H8), or homoallelic for pal ^#x002B;+ allele (H7). These techniques enabled us to segregate homokaryons of the four types defined above and were indispensable in the segregation of the pal ^– homoallelic homokaryons as no basidiospores were produced by typical pale mushrooms.     

Phenotypic analyses of frz and dif double mutants of Myxococcus xanthus

Myxococcus xanthus is a Gram-negative gliding bacterium that aggregates and develops into multicellular fruiting bodies in response to starvation. Two chemosensory systems (frz and dif), both of which are homologous to known chemotaxis proteins, were previously identified through characterization of various developmental mutants. This study aims to examine the interaction between these two systems since both of them are required for fruiting body formation of M. xanthus. Through detailed phenotypic analyses of frz and dif double mutants, we found that both frz and dif are involved in cellular reversal and social motility; however, the frz genes are epistatic in controlling cellular reversal, whereas the dif genes are epistatic in controlling social motility. The study suggests that the integration of these two chemotaxis systems may play a central role in controlling the complicated social behaviors of M. xanthus.     

Timing and success of reproductive stages in the seagrass Zostera noltii

The timing and success of sexual reproduction of the seagrass Zostera noltii was investigated at the Ria Formosa lagoon, Portugal. Thirty plants were tagged and monitored individually through time to determine in situ the development time of each maturation stage, from the emergence of the flowers to the production of seeds. The overall process of flowering and fruiting lasted 47 ± 4 days, during which formation and maturation of the fruits was the most time-consuming stage (27 ± 2 days). Spathe success, i.e. the percentage of spathes that produced seeds, was 22 ± 4% while spathe mortality was 34 ± 6%. A considerable percentage of spathes (37 ± 7%) was lost through leaf detachment, but some of these may still add to the reproductive success of the species by contributing to the species recruitment within the source meadow or elsewhere. Meadow seed production (MSP) of Z. noltii was estimated to be 312 ± 66 seeds m⁻², whereas the potential seed production of the studied meadow was 2623 seeds m⁻². Under laboratory conditions, 70% of Z. noltii seeds germinated within 26 days, but only 10% reached the seedling stage due to the high mortality of germlings. Fertility, defined as the probability of a seed to originate a new plant, was estimated to be 14 × 10⁻⁴, which is higher than what is expected for most seagrasses.     

Factors affecting seed rain beneath fleshy-fruited plants

We investigated factors affecting seed rain beneath nine fleshy-fruited fruiting plant species growing in a 1-ha plot of planted Pinus thunbergii in central Japan. We tested whether the numbers of seeds and seed species dropped by birds beneath fruiting plants were correlated with the number of fruits removed by birds from the plants. Most of fruiting plant species with high fruit removal had significantly high seed rain. Both the numbers of seeds and seed species dropped were significantly, positively correlated with the number of fruits removed across for all fruiting plant species. Therefore, fruit removal predicted the difference among heterospecific fruiting plants in seed rain. We also tested whether the number of fruits removed from fruiting plants by birds was related with fruit crop size, fruit size, and height of the plants, and the numbers of fruits and fruit species of neighboring plants near the plants. Most of fruiting plant species with high fruit crop size had significantly high fruit removal. The number of fruits removed was significantly, positively correlated with both the fruit crop size and the number of neighboring fruits across the nine fruiting plant species. However, the effect of the neighboring fruit density on fruit removal was lower remarkably than that of fruit crop size. Therefore, fruit crop size best predicted the differences among heterospecific fruiting plants in fruit removal. We suggest that fruiting plant species with high fruit crop size and high fruit removal contribute to intensive seed rain beneath them. This revised version was published online in June 2006 with corrections to the Cover Date.     

Certain phenological characters of the shrub layer of Kumaun Himalayan forests

The phenology of 49 shrub species in five forest types occurring along an altitudinal gradient (350–2150 m) in Kumaun Himalaya has been studied. The evergreen leaf-exchanging taxa accounted for nearly half of the species, the remaining half was nearly equally divided between an evergreen continual leaf drop type and deciduous taxa. The percentage of species with lengthy leaf drop increased with elevation and finally leveled off. At each site the maximum leaf drop period coincided with the warm dry period. Percentage of species with multiple leaf flushing was low for all forests. The degree of extended leafing decreased with increasing elevation along which summer dryness also decreased. Earliest leaf initiation was observed for evergreen continual leaf drop species, followed by evergreen leaf-exchanging, and deciduous types.For each forest, two peaks of flowering activity occurred, one during the warm dry period and the other in the warm wet period. The percentage of species with multiple flowering increased with increasing elevation. Nearly half of the species bore fleshy fruits. The mature fruit retention period for different forests ranged from about 2–3 months.The proportion of deciduous species was similar in trees and shrubs; leaf drop was common during the summer season for trees, while it was common during the winter season for shrubs; the proportion of species with multiple leafings was greater and leaf initiation earlier in shrubs than trees; and generally shrubs showed two flowering peaks and trees only one.Nomenclature follows Osmaston (1926).Financial support from the Gaula Catchment Eco-development project and the Department of Science and Technology, Government of India, is gratefully acknowledged. We thank Dr. Y. P. S. Pangtey for his help in plant identification.     

Phenological patterns among plant life-forms in a subtropical forest in southern Brazil

Phenological patterns in tropical plants usually are associated with the clear seasonality of rainfall associated with very different wet and dry seasons. In southern Brazil, in a subtropical forest with no pronounced dry season (average annual precipitation = 1389 mm, minimum monthly average c. 75 mm), plant phenology was studied to test for patterns (periodicity), to examine how phenological patterns vary among life-forms, and to test whether phenological cycles are associated with climatic variables. Thirty-seven plant species in four life-forms (trees, shrubs, lianas and epiphytes) were studied for 2 yr (1996-98) in an Araucaria forest remnant in southern Brazil, in the state of Paraná. Correlation and multiple regression methods established relationships between phenology and climate in terms of daylength, temperature and rainfall. In this Araucaria forest, plants showed seasonality in most life-forms and phenological phases. Leaf-fall, with its peak during the drier months (April to July), was the most seasonal. Flushing and flowering occurred during the wetter months (September to December), while fruiting occurred all year long. Phenologies varied among life-forms, and were strongly associated with daylength or temperature of preceding months, suggesting that plants receive their phenological cues well in advance of their phenological response. Phenologies in this Araucaria forest appear to be associated with the most predictable and highly correlated of the climatic variables, daylength and temperature and least so with rainfall, which is unpredictable.     

杉木种子园种子产量及其主导影响因子的分析

 为研究我国杉木种子园产量的主导影响因子及影响效应,调查收集了安徽西田、福建洋口和官庄、广东小坑4个林场杉木（Cunninghamia lanceolata）种子园历年种子产量及与种子生产年份对应的有关气象资料,以开花受粉、幼果发育各个不同时期的20个气象因子与种子产量进行逐步回归分析,探讨我国杉木种子园产量的大小年现象及周期特征。研究结果表明,杉木种子园投产初期大小年现象不显著,投产中、后期大小年现象出现的年度及周期特征完全一致,种子大小年周期一般为2～3年。在同一地区气候条件相似的情况下,即使立地条件、     

Effect of trehalose on the spawn storage in some edible mushroom fungi (2): Effect on preservation in the freezer

 We describe the effects of trehalose on spawn storage in a home freezer (average temperature, −16°C) where edible fungi usually do not survive. When the mycelia of Lentinula edodes were stored in a freezer for 3 days, the survival rate of mycelia cultivated on 2% glucose medium was 30%, whereas those on media containing 2% and 5% trehalose were 50% and 60%, respectively. Addition of trehalose to the culture was more effective in Pleurotus ostreatus. These results suggest that trehalose played the role of a stress protectant against freezing, because the mycelia cultured on a trehalose medium grew more rapidly and produced more fruiting bodies compared to those cultured on glucose. Received: February 6, 2002 / Accepted: October 1, 2002 Acknowledgments This work was partially supported by a Grant in Aid for Scientific Research (c) (2) No. 12660156 from the Japan Society for the Promotion of Science. We also gratefully acknowledge a grant from Hokuto Foundation for the Promotion of Biological Science. Correspondence to:T. Terashita