| Chinese jujube, Ziziphus jujuba Mill, is an important starch tree species belonging to the ecological and economic type of fruit trees. In recent years, Hengyang city, Hunan Province, has made full use of the local purple shale to produce fresh jujube. However, in the process of variety selection, inappropriate cultivars have been used, and obvious problems exist which are expressive of fruit low quality and poor arrangement of varieties. In order to solve these problems, fourteen varieties grown in the area for the produce of fresh jujubes were used as test material for experimental data on height increment, fruit characteristics, disease resistance, and per-plant yield, using the method of field trial combined with field survey and Multidimensional Value Theory based comprehensive evaluation. In addition, top grafting was applied to upgrade the poor quality stands. The main results were as follows:1. Survey of growth and fruiting habits showed that all of the fourteen varieties of fresh jujube grown in the area could normally flower and fruit. Among them ’Qiyuexian’,’Fucuimi’,’Yueguang’,’Tezaosihao’,’Tangzao’, and’Hunanjidanzao’ demonstrated a precocious habit, while ’Zaocuiwang’ and’ Lizao’ matured in the middle season, but ’Jinsisihao’,’Luzaowuhao’,’Zhanhuadongzao’,’Jinmangguozao’,’Erdaidongzao’, and ’Pingguodongzao’ were late varieties. For individual fruit weight, the maximum was found in’Erdaidongzao’, making27.89g per fruit, the minimum was found in ’Tangzao’, being8.84g per fruit, with the average being16.84g per fruit. Fourteen varieties grew well and height growth of two-year old’Jinsisihao’was the maximum of263.5cm, while the height value of the two-year old’Erdaidongzao’ was the minimum of176.2cm, with the mean value being212.21cm.’Erdaidongzao’,’Luzaowuhao’and’Zhanhuadongzao’showed strong resistance to jujube anthracnose and the disease indexes were0.6,0.6and0.9respectively;’Erdaidongzao’,’Zaocuiwang’ and ’Tezaosihao’had strong resistance to rust disease and the disease indexes were24.0,26.4and26.5respectively;’Yueguang’,’Qiyuexian’ and ’Zhanhuadongzao’ had strong resistance to jujube-fruit shrink disease and the disease indexes were1.8,2.1and2.5respectively. Fruit yield of two-year old trees of the fourteen varieties varied significantly, with the mean value being3.29kg per tree. While ’Jinmangguozao’ was the highest with4.2kg per plant, and the yield of ’Jinsisihao’ and ’Qiyuexian’ was medium with3.8kg per plant and3.7kg per plant respectively, the low yield was found in ’Tezaosihao’ and ’Zhanhuadongzao’ with2.7kg per plant and2.4kg per plant respectively.2. Comprehensive assessment of the fourteen varieties by the factors of growth, fruiting, disease resistance, and productivity showed that, through Multidimensional Value Theory and Reasonable Satisfaction, some varieties might bear all of the good characteristics, but most of the varieties varied significantly in one way or another. In evaluation of growth properties, the score value of ’Hunanjidanzao’ was the highest, followed by ’Yueguang’,’Jinmangguozao’, the score of ’Lizao’,’Pingguodongzao’,’Qiyuexian’ was lower, others ranked in between. In evaluation of fruit qualities, score values of ’Erdaidongzao’,’Fucuimi’,’Jinsisihao’ were higher, followed by ’Luzaowuhao’,’Yueguang’,’Zhanhuadongzao’, the score for ’Jinmangguozao’,’Tangzao’,’Lizao’ was lower. In evaluation of diseases resistance, the score values of ’Erdaidongzao’,’Luzaowuhao’,’Zhanhuadongzao’ were higher,’Jinmangguozao’,’Qiyuexian’,’Lizao’ were lower. In evaluation of fruiting capacity by per-tree yield, the higher was ’Jinmangguozao’,’Jinsisihao’,’Qiyuexian’, The performance of ’Zaocuiwang’,’Tezaosihao’,’Zhanhuadongzao’ was poor in production. In overall evaluation of the above four variety factors, better quality was shared by ’Erdaidongzao’,’Luzaowuhao’,’Jinsisihao’,’Yueguang’, and ’Fucuimi’, of which the satisfaction score was0.69,0.68,0.65,0.65, and0.63, respectively;’Tangzao’,’Zaocuiwang’ and ’Lizao’ had lower satisfaction sores as0.39,0.38and0.34, respectively; the score of other varieties ranked in between.3. Study on top-grafting technique for the senile jujube trees showed that, the time of grafting presented significant effect on the survival rate and shoot growth. When the graft was made in March or early April, the length of new shoots was158.5cm, but the graft survival rate was only60.47%. From early July to the middle of July the survival rate of grafting was90.91%, but the length of new shoots just made35.1cm. The survival rate and shoot growth also differed greatly with the grafting method. The average survival rate of bark grafting, cut grafting and cleft grafting was86.84%, 82.50%and71.11%, respectively, and, the annual growth of young sprouts was158.5cm,143.9cm and116.5cm, respectively. Single-bud grafting proved to be the best method, producing shoot growth of156.2cm,8.1second-time shoots, and an average length of second-time shoot of13.4cm. Different scion size varied significantly in the survival rate and shoot growth:0.8-1.2cm was the best size, which saw a survival rate of84.44%and a well developed young sprout by162.7cm annually. The scionwood taken from the middle part of the the developing shoots was the best for a high survival rate of89.09%and a good sprout growth by128.4cm annually.Study on different plant growth regulators showed that6-BA, NAA, IAA and GA3, if in appropriate concentration, all played a good role in the increase of survival rate. In mid March to early April the use of suitable concentration of plant growth regulators could improve the survival rate of grafting. Orthogonal design test showed that the optimal proportion of different plant growth regulators was revealed in50mg/L NAA+200mg/L IAA+20mg/L GA3, by that combination the graft survival rate was95.14%and mean annual growth of young sprouts was194.2cm. |
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