Studies On The Characteristics Of Pollination And Seed Quality In Seed Orchard Of Japanese Larch

Japanese larch (Larix kaempferi (Lamb.)carr ) is one of the most important timber tree used widely. It can grow healthy and fast in warm weather area. It can tolerate soil moisture, plant diseases and insect pests. Although Japanese larch seed orchard is the base of producing sound seeds with high heredity and planting quality, there are many problems in seed production, such as low seed output with low quality, and the phenomena of interval between bumper and off year. The shortage of high quality seeds is a big problem for forestation in some districts. We have discussed the morphological characteristics of female cone and male cone, cones distribution in the mother tree crown, florescence synchronization for male and female, the output of pollen and ovule among different clones, pollen dispersal and its spatial distribution, seeds distribution in the cone, seeds quality among different families and so on. The results obtained are:(1) During the evolution, the male cone of Japanese larch has formed the morphological constriction being good for pollen dispersal and protecting pollen from raining. Male cone has also formed the morphological constriction which can help ovule to be pollinated and fertilizing well. Same clones' florescence are different from each other in different district; Different clones' florescence are different from each other in the same district. Male cones often distribute on 2-3 years old branches; most cones favorite distribute in the south part of the crown in the same horizontal level and most cones distribute in the middle of the crown in the vertical. Pollen dispersal can be divided into four periods: initial stage, flourishing stage, final stage, and finishing stage; Female cone pollination is also divided into four periods: initial stage, flourish stage, final stage, and finishing stage.(2) Japanese larch pollen dispersal has a rhythm of low-high-low during the whole pollen dispersal period; pollen quantity in space has significant difference among days; pollen dispersal rhythm is affected by climate dramatically; a peak time of 3-5 days usually appears during the whole period. Pollen dispersal has a rhythm of low-high-low during the day; the peak time of each day appears in 10:00-16:00, which is affected by weather; pollen quantity in space during different time of each day also has significant difference. The accumulation number of pollen during the whole period is 2.159 grain/ mm~2 in 2004, and 2.390 grain / mm~2 in 2005 respectively. Pollen distributions in space...