Effects Of Greenhouse Conditions And Foliar Sprayed ALA On Forcing Culture Of Tree Peony Flowering

As one of Chinese traditional flowers, peonies (Paeonia suffruticosa Andr.) were very popular andrespected for most of people. However, its flowering period is shorter and only concentrated in spring,which greatly limit the development of the tree peony. Therefore, the technology of tree peony forcingculture should be further studied.12cultivars that have different blooming periods and flower colorswere studied on their dormancy characteristics, and the effects of greenhouse conditions andexogenous ALA on tree peony forcing culture were investigated in this paper. The results were asfollowing:(1) Relationship between chilling requirement and flower quality of12peony cultivarsAll tree peony cultivars in this study with different blooming periods, flower colors, and flowershapes can be forcing cultured, but their ornamental values varied. According to their flower quality indifferent target flowering time, the12chosen cultivars were classified into3categories. Type I (suitablefor earlier winter flowering time):'hongxiazhenghui','qiufa5hao'and 'chunhongjiaoyan', whichchilling requirement is480h. Type Ⅱ (suitable for medium winter flowering time):'caozhouhong','wujinyaohui','guanqunfang' and 'yinhongqiaodui', which chilling requirement is514h; TypeⅢ(suitable for later winter flowering time):'zierqiao','zhuguangmorun','luhehong','wulongpengsheng'and 'Kaoh', which chilling requirement is572h and these five cultivars need moreeffective accumulated temperature.(2) The effects of different conditions of greenhouse on tree peony flowering qualityThe flowering quality of forcing culture peony in glass greenhouse is better than in sunlightgreenhouse. The main reasons were caused by the different relative air humidity(RH) and lightintensity in different greenhouse. Glass greenhouse has an enviroment with low RH and strong light. Atthe late fowering stage(the flower bud), the RH were keeping at80%and the light transmission(LT) was40.55%in glass greenhouse, yet in sunlight greenhouse the RH were keeping at90%~95%and theLT was26.56%.The plants(at the late fowering stage)in the sunlight greenhouse were transferred into the glassgreenhouse,10days later, the leaf chlorophyll content and accumulation of photosynthetic products andthe leaf dry matter were all significantly increased, and thus the leaf petioles became upright and theplant form were better compact. But at the same time the plant in glass greenhouse transferred into thesunlight greenhouse, the color and the chlorophyll content of the leaf and accumulation ofphotosynthetic products had little significant difference. The higher RH of the sunlight greenhouseprevented the stomatal gas exchange, so there had a negative effect on photosynthetic net rate.(3) Preliminary study of foliar sprayed ALA on tree peony forcing cultureDifferent concentrations of5-ALA (50,100, and200mg/L) were foliage sprayed treating duringearlier bud stage of tree peony. The results showed that ALA treatment could be significantlyincreased the growth rate of flower buds and new branches for both of "Zierqiao" and "Qiaohongzhengyan". The flowering time was advanced for2-3days, and the blooming periods wereextended3-4days of both cultivars. Net photosynthetic rate, transpiration rate, and stomatalconductance of tree peony foliage were significantly increased compared with the control; however,there was no significantly difference of above research contents among the three treatments. Thus50mg/L of5-ALA was recommended in production practice.