Yearly Difference in Normalized Seed Weight of Cultivated Iris dichotoma Pall. in Mongolia

摘要

Maximum of mean seed weight was observed at 1997 while normalized seed weightwas signifi cantly higher at 1982 and 1995, compared with other years. Seed weightvariation is positively correlated with mean seed weight for earlier rainy seasonyears, excluding later rainy season years (1982 and 1995). Low and high seedweight variation associated for years with colder and wetter in May and with hotterand drier in May, suggesting drought in May might be eff ective on seed weightvariation of I. dichotoma. Moderate normalized seed weight associated for yearswith hotter in June, while high and low normalized seed weight for years with coolerand cool in June, suggesting I. dichotoma might use both photosynthetic productionsand under-ground-storage for seed maturity. Mean seed weight and seed weightvariation were linked to precipitation amount, whereas normalized seed weight waslinked to precipitation periodicity. Seed weight variation detected delay of regrowth,caused by early drought, while normalized seed weight suggested seed weightresponse to complete seed maturation after droughty season, using photosyntheticproductions and under-ground-storage. The results suggest that normalized seedweight might be useful to recognize seed weight response of I. dichotoma forclimatic factors, better than mean seed weight and seed weight variation.