Graft Compatibility And Photosynthetic Characteristics Reaserch Of Different Rootstock-scion Combinations Of Honey Pomelo At Seedling Stage

Citrus grandis cv.’Guanximiyou’ which originated from Fujian province in China is subtropical evergreen fruit tree. It is one of Chinese most important cultivated varieties. Citrus grandis cv.’Hongroumiyou’, Citrus grandis cv. ’Hongmianmiyou’. Citrus grandis cv.’Sanhongmiyou’, Citrus grandis cv. ’Huangjinmiyou’ are good cultivars selected from the bud mutation of ’Guanximiyou’,These varieties are colorful and rich in carotenoids and vitamin C and other antioxidants which have great health value and loved by consumers. It has resulted in hugeeconomic losses after the introduction of ’Hongmianmiyou’ in Sichuan province because of the inappropriate selection of rootstock-scion combinations.Grafting is the only means of honey pomelo breeding and the graft compatibility, fruit yield and quality of rootstock-scion combinationshave significant differences. In order to evaluate graft compatibility of different honey pomelo [Citrus grandis (Burm.) Merril] rootstock-scion combinations at seedling stage, some physiological and biochemical indexes of 15 rootstock-scion combinations at seedling stage were determined Their graft compatibility was evaluated by usingprincipal component and cluster analysis.The main results are as below:1. There were significant differences in seedling growth among different rootstock-scion combinations, which ’Hongmianmiyou’/Ponciurs trifoliata and ’Huangjinmiyou’/Poncirus trifoliata combinations were imcompatibility. The preservation rate, ability of growth and sprouting of combinations which the rootstock is Citrus grandisare best. From the production practice in Sichuan and Chongqing province, we can know the cmbinations which the rootstock isCitrus junoshave early fruiting and high yield characteristics. Citrus junos may be one of the potential rootstocks of honey pomelo in Sichuan and Chongqing province. But it needs to wait for further investigation.2. The changes in PPO, POD activities, soluble protein, soluble sugar contents were similar at graft union stage in different rootstock-scion combinations while the PPO and POD activity in the ’Hongmianmiyou’/Poncirus trifoliata and ’Huangjinmiyou’/Poncirus trifoliata combinations showed significant differences, to some extent, reflects the process of graft union.3. Principal component analysis showed that four main components basically present 91.33% information of 15 indexes. The first principal component have significant correlationwith the graft preservation rate, plant height, growth index, the total number of shoots and total shoot growth and total leaf shoots, so it can be named as the new variables related to plant growth.The cluster analysis showed that 15 rootstock-scion combinations could be divided into 4 clusters. Comprehensive analysis of seedling performance can be drawn:’Guanximiyou’,’Hongroumiyou’ and ’Sanhongmiyou’ can use Poncirus trifoliataand Citrus grandisas rootstocks. ’Hongmianmiyou’ and ’Huangjinmiyou’ can use Citrus grandisas rootstocks.The 5 honey pomelo could use Citrus junos as rootstock.’Hongmianmiyou’ and ’Huangjinmiyou’ cannot use Poncirus trifoliateas rootstock.4. The results showed that diurnal change in net photosynthetic rate(Pn)of 6 combinations leaves was a typical bimodal curve.At the middle of August, ’Hongmianmiyou’/Poncirus trifoliate appear chlorotic desease. The results of decrease of Pn is the sharp decline of Chl.’Guanximiyou’/Citrus junos and ’Hongmianmiyou’/Citrus junos have demonstrated strong photosynthetic capacity. It is important to accumulation of photosynthetic products, improvement of yield and fruit quality.