Abstract Phonological period and fruit quality of Jingganghongnuo （JGHN） grafted on the rootstocks of Feizixiao （FZX）， Heiye （HY） and Huaizhi （HZ） respectively were recorded and comparatively studied from 2015 to 2017. The results showed that the whitish millets and flowering stage of JGHN grafted on FZX and HY rootstocks were respectively 3-17 days and 1-3 days earlier than those on HZ. While the fruit maturation stage was 5-7 days ahead of in the same comparative situation. Compared to fruits grafted on HZ， mean fruit weight of JGHN grafted on HY and FZX were 38.1% and 35.8% bigger respectively than that on HZ. In addition， more closely heart??shaped and brighter pericarp color of JGHN fruit were observed with rootstock of HZ than that with other two kinds of rootstocks. In terms of aborted??seed rates of JGHN， average value with rootstock FZX was 81.7%， which was 58.0% higher than that with HY， and 2.49 times of those with HZ. Vc content of JGHN grafted on HY and FZX were 30.47 and 25.86 mg/100 g respectively， significantly higher than that grafted on HZ. TSS and TA of JGHN grafted on HZ were 17.8% and 0.14%， both were obviously higher than that grafted on FZX and HY.
　　Key words Jingganghongnuo； Stions； Phonological phase； Fruit quality
　　Jingganghongnuo is high??quality late maturing litchi variety screened from a litchi tree in Gaobu Village， Chengjiao Town， Conghua City， Guangdong Province by the experts in litchi breeding post of China Litchi and Longan Research System. It was approved and named by Guangdong Crop Variety Examination and Approval Committee on February 4， 2009， and approved by National Tropical Crop Variety Approval Committee on July 5， 2015. The variety has good fruit appearance， thick flesh， sweet flavor， high percentage of aborted seed， good crack resistance， good high yield stability， strong disease resistance， late mature stage， and tolerance to storage and transportation， with broad market prospects， which is suitable to be planted in late maturing litchi cultivation area， such as Guangdong， Fujian， Yunnan and Sichuan[1-3].
　　Grafting reproduction is an important manner of maintaining fine characters of litchi variety and shortening production period of new variety. The grafted litchi variety could enlarge cultivation range， increase yield or improve other traits by using excellent characteristics of the rootstock[4]. Meanwhile， the rootstock directly affects normal growth， flowering and resulting， fruit yield and quality of the scion variety[5]. Jingganghongnuo （JGHN） is suitable to be grafted on the rootstocks of Huaizhi （HZ）[6]， Heiye （HY）， Feizixiao （FZX， suitable for grafting of big branches）[7]， Dahongpao[8]， Shuangjianyuhebao[9]， Liuyuexue[9]， Baitangying[9]. Since 2011， Shenzhen combined experiment station of China Litchi and Longan Research System successively introduced JGHN and other excellent??quality litchi varieties in Huilai County of Jieyang， Guangdong and carried out test study， which could lay the basis for structure adjustment of litchi variety in Huilai production district. Main litchi varieties in Huilai production district are HZ， HY and other low??efficiency litchi varieties， and they all could be taken as the rootstock of JGHN （excellent??quality late maturing litchi variety） in the theory. To deeply understand the performance of JGHN grafted on different rootstocks in Huilai production district， top grafting experiment taking FZX， HY and HZ as the rootstocks was conducted in Yingshinei Orchard of Shenquan Town， Huilai County in 2011 and 2012， and comparative analysis on phenological period， yield and fruit quality of JGHN grafted on different rootstocks was conducted. The grafted JGHN started to sporadically fruit in 2014 and normally produce in 2015. In this paper， phenological period and yield of JGHN grafted on different rootstocks were recorded during 2015-2017， and quality determination and analysis of mature fruit were conducted， to study the influence of different rootstocks on phenological period and fruit quality of JGHN， which could provide the related basis for its promotion plantation in Huilai production district. 　　Materials and methods
　　The test was implemented in Yingshinei Orchard of Huilai County， Jieyang， Guangdong in 2011 and 2012. The soil is acid red soil， and pH is 4.51， with 376 mg/kg of total potassium， 50.5 mg/kg of available potassium， 10.26 mg/kg of effective phosphorus， 10.9 g/kg of organic matter， 53.4 mg/kg of alkali hydrolysable nitrogen， 0.75 mg/kg of effective zinc， 106.21 mg/kg of effective calcium and 0.58 mg/kg of effective boron.
　　There were 3 kinds of test rootstocks， and they were FZX planted in 1992?¨grafted seedlings， FZX was middle stock， and the anvil was a seedling??， HY?¨anvil??and HZ?¨anvil??. Grafting method was top grafting， they were all big branch grafting， and the height of grafting union was 80-120 cm. The scion JGHN was provided by the experts in litchi breeding post of the national litchi and longan industry technical system. The grafting time was in March of 2011， the expanded grafting was conducted in March of 2012， and there was no incompatibility between stock and scion. Little JGHN grafted on FZX started to fruit in 2014， while JGHN grafted on three kinds of rootstocks fruited during 2015-2017.
　　Phenological period of production for JGHN grafted on different rootstocks during 2015-2017 was recorded. 5 JGHN litchis trees grafted on different rootstocks were randomly selected in mature period. According to 5 directions of east， south， west， north and middle， 3 spikes of fruits were collected at each direction. Fruit spike of JGHN grafted on the same rootstock was collected to remove branch， leaf and carpopodium， and single fruit was mixed. 20 normal fruits without disease， insect and mechanical injury were randomly selected for quality determination， and the determination indexes contained the weight per fruit， vertical， horizontal and lateral diameters of the fruit， flesh thickness， peel weight， peel thickness， edible rate， seed weight， aborted seed， peel chromatic aberration， total soluble solid?¨TSS??， titratable acid?¨TA??， total sugar?¨TS??， vitamin C?¨Vc??[10]. Weight determination used Mettler Toledo electronic balance， and the determination of vertical， horizontal and lateral diameters and thickness selected 0-200 electronic digital vernier caliper. The determination of peel chromatic aberration selected Japan Minolta CR??400 type of automatic chromatic aberration meter， which was expressed by L*， a* and b*. Among them， the larger the L* value， the brighter the peel， and it was darker conversely； the bigger the a* value， the redder the peel， and it was greener conversely； the bigger the b* value， the yellower the peel， and it was bluer conversely. TSS content was determined by Japan Atago PAL??1 digital display refractometer； Vc content was determined by 2，6??dichlorophenol method， mg/100 g?¨FW??[2]； TA content was determined by sodium hydroxide titration[9]； TS content was determined by anthrone??concentrated sulfuric acid[11]. 　　Results and analyses
　　The influence on production phenological period of JGHN by different rootstocks
　　The comparison on phenological period of JGHN grafted on different rootstocks during 2015-2017 was shown as Table 1. Table 1 displayed that the growth of JGHN grafted on FZX and HY was more prosperous than that grafted on HZ under the same soil， climate and management level， mainly showing in the growth and old maturing of autumn shoots. Among them， the plant grafted on FZX grew autumn shoot for three times in 2015. Calculated by autumn shoot growth for two times every year， old maturing time of terminal tip of JGHN grafted on FZX was earlier than that grafted on HY and HZ. Whitish millets stage of JGHN grafted on FZX was close to that grafted on HY， which was 3-17 d earlier than that grafted on HZ. Initial flowering stage of JGHN grafted on HZ was 1-3 d later than that grafted on FZX and HY. Fruiting period of JGHN grafted on FZX was close to that grafted on HY， which was 3-5 d earlier than that grafted on HZ. Physiological fruit fallen stage of JGHN grafted on FZX and HY was close， which was 3-10 d earlier than that grafted on HZ. Seen from fruit ripening period， JGHN grafted on FZX and HY was close， which was 5-7 d earlier than that grafted on HZ.
　　The influence on JGHN yield by different rootstocks
　　The tracking results on the yield of JGHN grafted on different rootstocks during 2015-2017 （Table 2） displayed that JGHN grafted on FZX， HY and HZ all showed the characteristic of stable production under the same management level and climate condition. Due to the influence of adverse climate in 2016 and 2017， the yield of JGHN grafted on FZX and HZ slightly declined， but not obvious. The yield of JGHN grafted on HY was the minimum in 2016. Average yield per plant in recent 3 years displayed that the yield of JGHN grafted on FZX and HY was close， while the yield of JGHN grafted on HZ was the lowest.
　　The influence on appearance quality of JGHN fruit by different rootstocks
　　Seen from Table 3， different rootstocks had obvious influence on appearance quality of JGHN fruit. Peel color is the most intuitionistic factor reflecting appearance quality of litchi fruit. Determination result of chromatic aberrationof JGHN grafted on different rootstocks displayed that both L* and a* values of JGHN grafted on HZ were the maximum， showing that peel color was redder than other two groups， while L* value of JGHN grafted on FZX and HY was close， and a* value of JGHN grafted on FZX was bigger than that grafted on HY. In conclusions， peel color of JGHN grafted on HZ was better than that grafted on FZX， while peel color of JGHN grafted on HY was the worst. 　　Table 3 also displayed that the weight per fruit in different stock-scion combinations had obvious difference， in which average weight per fruit of JGHN grafted on HY and FZX was close， which was respectively 38.1% and 35.8% bigger than that grafted on HZ. The influence of different rootstocks on appearance quality index of JGHN fruit also embodied in fruit shape. First， 3??year means of longitudinal diameter， transverse diameter and lateral diameter of fruit had obvious difference. Second， fruit shape index showed as FZX??HY??HZ， illustrating that heart shape of JGHN grafted on FZX was shorter than that grafted on HY and HZ， and fruit shape of JGHN grafted on HZ was closer to positive heart shape. Peel thickness of JGHN grafted on the three kinds of rootstocks was respectively 1.12， 1.02 and 0.99 mm， in which peel of JGHN grafted on FZX was the thickest， followed by HY and HZ. Peel thickness is an important factor affecting the tolerance to storage and transportation of fruit， and litchi with thick peel is favorable for storage and transportation. The percentage of aborted seed and edible rate are also important indexes of judging litchi fruit quality. The percentage of aborted seed of JGHN in different stock-scion combinations had obvious difference， and the percentage of aborted seed of JGHN grafted on FZX was 81.7%， which was 58.0% higher than that grafted on HY and was 2.49 times of that grafted on HZ. It was clear that aborted seed characteristic of FZX rootstock had obvious influence on JGHN. Edible rate of JGHN grafted on HY was obviously bigger than that grafted on FZX， while edible rate of JGHN grafted on HZ was the lowest， which was related to the percentage of aborted seed and peel thickness.
　　The influence on internal quality of JGHN fruit by different rootstocks
　　Seen from Table 4， TSS， Vc， TA and TS of JGHN grafted on different rootstocks had obvious difference. Among them， 3??year mean of Vc content was the highest in JGHN grafted on HY， followed by FZX， and it was the lowest in JGHN grafted on HZ. TSS content of JGHN in different stock-scion combinations had smaller difference， in which it was slightly higher in JGHN grafted on HZ， and 3??year TSS mean of JGHN grafted on FZX and HY was the same. TA content of JGHN grafted on FZX was the lowest， while it was the highest in that grafted on HZ， followed by that grafted on HY. TS content of JGHN grafted on HY was the highest， followed by that grafted on HZ， and it was the lowest in JGHN grafted on FZX. TS/TA is an important index of judging internal quality of litchi fruit. TS/TA in mature fruits of JGHN grafted on the three kinds of rootstocks was all more than 130， in which it was the highest in JGHN grafted on FZX and was the lowest in that grafted on HZ. 　　Conclusions and discussion
　　The cause for different rootstocks affecting phenological period of JGHN
　　Phenological period and yield change of litchi are closely related to ecological conditions （temperature， water， soil， sunshine and wind）， nutrition absorption and accumulation of tree body， generation and distribution of endogenous hormone[4]， as well as stock-scion combination. Under the same ecological condition and cultivation management level， the influence of rootstock on phenological period of JGHN is relatively obvious. Maybe after the graft heals， tissue structure of litchi rootstock and scion tends to be the same[5]. The transportation and transmission of mineral nutrition and endogenous hormones in rootstock itself affect scion， and play dominant role after full healing， thereby making phenological period and yield of JGHN grafted on different rootstocks have the difference. The influence mechanism of rootstock on phenological period and yield trait of scion variety also needs deeper research and exploration.
　　The cause for different rootstocks affecting fruit quality of JGHN
　　Fruit quality of litchi is closely related to cultivation management technology and ecological factors ?¨sunshine， water and temperature??， as well as nutrition absorption status of root system， nutrient transportation of tree body[4]. Under the same cultivation management condition and ecological factor， the influence of tree itself status on litchi fruit quality is embodied. For the grafted litchi variety， rootstock variety is key factor of affecting its tree body status. Therefore， fruit quality of JGHN grafted on different rootstocks is different， and the causes contains two aspects. First， different root system distribution， root number and density of various rootstock varieties cause the difference in absorption velocity and efficiency of mineral nutrition， thereby causing the difference in quality index of JGHN fruit. Zhao et al.[12] analyzed fruit quality and aroma substances of Hongjiangjun apple grafted on different rootstocks. The results showed that different rootstocks had obvious influence on weight per fruit， Vc， TA， TSS and soluble sugar content of Hongjiangjun apple. Huo et al.[13] analyzed growth， quality and yield of apple in different stock??scion combinations， and found that quality indexes （fruit size， fruit shape index， fruit color and TSS） and yield of apple grafted on different rootstocks had obvious difference. Xie et al.[14] studied the influence of four kinds of rootstocks on fruit size and quality of Fuji apple， and the results showed that 4 kinds of rootstocks all had certain extent of influence on fruit size and quality indexes （sugar， acid and vitamin） of Fuji apple. Guo et al.[15] studied the influence of different citrus rootstocks on Jincheng fruit quality. The results showed that different rootstocks affected mineral nutrition metabolism and tree body growth condition of Jincheng， thereby affecting external and internal quality of its fruit. Although there is no related report on the influence of different rootstocks on litchi fruit quality， litchi， apple and citrus have certain same principle based on the conclusions in this paper. After FZX， HY， HZ and JGHN scion completely heal， nutrient transport tissues （root system， xylem and phloem） of the rootstock affect mineral nutrient transport and crown formation of the grafted tree. Leaves of FZX and HY are larger than HZ， while their growth is more prosperous than HZ， and fruit shape is bigger than HZ. The research results showed that the fruit of JGHN grafted on FZX and HY was obviously larger than that grafted on HZ， and that may be caused by the above reason. Second， after grafting and healing， due to different rootstocks， different transmission systems of mineral and organic nutrition cause the difference in photosynthetic efficiency of JGHN crown and leaves， and different nutrient application in fruit development process[5]， finally causing that peel color， Vc， TA and TS of JGHN have obvious difference. 　　References
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