| Pollination and fertilization of a new loquat with early-maturity variety'Chuanzao loquat'was researched in its 1st florescence in order to reveal the reason for low fruit setting rate.The mechanism of temperature and soil moisture on fruit setting rate of 'Chuanzao loquat' in the 1st florescence was studied by investigating the temperature and soil water content. In order to preliminary screen out a certain number of loquat flower-fruit protection agent,7 kinds of plant growth regulators and 11 kinds of foliar fertilizer was sprayed in the flowering stage. This study would be of important scientific significance on revealing the reason for low fruit setting rate of 'Chuanzao loquat' and other early maturing varieties in the 1st florescence.The main results were listed as follows:1 Results of pollination and fertilization characteristics of 'Chuanzao loquat' showed that:(1)The 1st florescence of 'Chuanzao loquat' to enter beginning bloom stage was mid-July, full bloom stage was from late July to early Aug. and final bloom stage was from mid-Aug. to late Aug.The highest, lowest and average air temperature in the 1st florescence was 34.9?,18.9? and 26.03? respectively. The highest, lowest and average air humidity in the 1st florescence was 93.7%?41.9% and 71.7% respectively (2)Anther structures mostly developed normally, and was able to crack out mature pollen grains, there were a few empty anthers, and many ovule structure was dysplastic, including less number of ventricle and ovules, empty ventricular without ovule, degraded ovule and embryo sac, ovules without embryo sacs.(3)The stigma with receptivity was on 0?4 d after flowering, the stigma with very strong receptivity and pollen with the highest viability was on 1 d after flowering. And then the pollen viability rapidly reduced.(4)Only a few pollen tubes had arrived in style base at 48 h and entered the ovule at 96h after self-pollination, but very few. Accordingly, the combination of many factors such as short duration of stigma strong receptivity, quickly reduction of pollen viability, abnormal ovule structure, few pollen tubes which could arrive at style base and enter the ovule. High temperature and low humidity were the important reason of low fruit-setting rate of 'Chuanzao loquat' in the 1st florescence.2 Effect of temperature on pollination and fertilization of'Chuanzao loquat'.The results showed that:(1)The duration of stigma with receptivity, the pollen vitality under the same flowers"age and the number of pollen tubes reached the style base were ranked as 25? day/20?night>30?day/25?night> 35?day/30? night, and the length of time of pollen tubes arrived at style base was ranked as 25? day/20? night>35? day/30? night> 30? day/25? night. The pollen tubes growth showed apex bending, swelling, stop growth and other anomalies in the style at 35? day/30? night.(2)SOD and CAT activity of flowers presented the trends of first increased then decreased with the increase of flowers' age, but POD presented the trends of first decreased then increased. The protective enzymes activities were maintained at a relatively stable level at 25? day/20? night, but changed significantly at 30? day/25? night and 35? day/30? night. Therefore, the duration of stigma receptivity was shorten, pollen vitality was reduced and pollen tube growth was deformed in style under high temperature, at the same time the response of antioxidant enzyme activity was intense, which accelerated aging of the flower. High temperature was one of the important external causes for bad fruit setting rate of 'Chuanzao loquat' in the 1st florescence.3 Results of the pot experiment of water controlling for'Chuanzao loquat'showed that:(1)Water stress significantly decreased the total number of flowers, the length of the inflorescence, anther, bud and style, the width of the inflorescence and anther, pollen vitality and germination, stigma receptivity and fruit setting percentage of'Chuanzao loquat' in the first florescence.(2)With the increase of soil moisture stress, the activity of SOD, POD and CAT of'Chuanzao loquat'in the first florescence significantly decreased, but the sensitivity to water stress of SOD, POD and CAT was different. SOD was sensitive to water stress, the activity of SOD was almost lost in severe water stress. Studies showed that soil water stress led to floral organ dysplasia of 'Chuanzao loquat' in the first florescence, and it reduced the flower number and decreased pollen viability and protective enzyme activity, causing poor pollination and fertilization, causing poor pollination and fertilization, many factors such as soil water stress in the flowering period was an important cause of the low fruit setting rate.4 Results of spraying different plant growth regulator and foliar fertilizer experiment showed that:(1)After spraying different plant growth regulators, fruit-setting rates were ranked as Propionyl brassinolide>Brassinolide>Water>Jingweifengsu=Bili=DA-6> Sodium nitrophenolate>CPA in descending, and no significant difference between Propionyl brassinolide and Water.(2)After spraying different kinds of foliar fertilization, fruit-setting rates were ranked as Good helper of multiple foliar fertilizer>Water soluble fertilizer with amino acids=Polymers boron>KangPuyepeng>JinWeiguo> KangPugaimeipeng>Lvweifenhuaguobao=Haizhaoshuan>Water>Tianda2116> Shoufentaiguosu>HuayePBO from large to small. The fruit-setting rates of Good helper of multiple foliar fertilizer, Water soluble fertilizer with amino acids, Polymers boron, KangPuyepeng and JinWeiguo were significantly higher than that of Water. Taken together, relative to other plant growth regulator and foliar fertilizer, spraying Good helper of multiple foliar fertilizer for improving fruit-setting rate of'Chuanzao loquat' in the 1st florescence was the best, but the increasing range was not very ideal, its relevant mechanism and actual production application remains to be further in-depth study. It also requires more research to solve the problem of low fruit setting rate of'Chuanzao loquat' in the 1st florescence. |
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