Take the ordinary banana transplanting seedlings as material, use potting experiment; take the seedlings that haven't been sprayed by plant growth regulator as the control group. In this paper, we study the effects of plant growth regulators on the growth, nutritional absorption and resistance physiology of banana planting big seedlings. The results show that compared with the control group, spraying gibberellin on the leaf can significantly increase the seedling height by27.75%, and increase chlorophyll content of 19.11%; effectively reduce MDA content of the leaf, increase proline content, increase SOD content of the leaf by21.94%, and increase POD content of 82.13%; compared with the control group, Spraying alpha-sodium naphthalene acetate can significantly increase the seedling diameter by 17.67%, increase the seedling dry matter cumulant of 16.11%, and increase the strong-seedling index by 21.49%; Improve nitrogen and phosphorus nutrient uptake, increased by 9.95% and 9.95% respectively. So in breeding process of banana planting seedlings, in order to get robust provisonal planting seedlings, we should consider to spray the intermixtures of gibberellin and alpha-sodium naphthalene acetate, or spray these two regulators at specific intervals. Fostering healthy and strong banana planting seedling that have strong adverse resistance is the foundation of stable and high banana yield. These days, the banana seedling transplanting, mostly happens in the summer and fall, and is accompanied by problems that the recuperating period is long, the seedlings grow weakly, the survival rate is low, which lead to irregularity of bananas plants growth in later stage. [1-2]. Every year, the cold in in winter and spring would damage banana production to the banana production areas in China, resulting in reduction of output, or even no harvest, which has become the factors restricting the development of the banana industry [3-4]. In addition, banana harvest time is too concentrated in China, which results in low banana prices, and discourage the enthusiasm of farmers [5-8]. So how to realize the seedling efficient transplanting, avoid the cold damage and adjust the harvest period is the key to high quality production of bananas. The current research has shown that on the basis of cultivating strong banana secondary planting seedlings, cultivate older planting seedlings, then transplant the seedlings to fields, which can effectively shorten seedling stage in the field, and avoid the harm from cold in the winter and spring, so as to realize the banana high quality production [6-8]. Therefore, the research on technology to foster robust older planting seedlings of banana is of great significance for the banana production. Studies have shown that gibberellin, multi-effect azole, alpha-sodium naphthalene acetate, Compound sodium nitrophenolate and diethyl aminoethyl hexanoate etc., are widely involved in the regulation of plant growth and development[8-13]. Gibberellin can promote plant growth, destroy the apical dominance, promote the growth of lateral branches, and break the dormancy, and regulate the flowering. Morphologically praying gibberellin on the crops would significantly promote the stem elongation, and within a certain range of concentration, as concentration is increased, the enhancement is increased [14]. Dipping the seedling root in Multi-effect azole can increase the survival rate. During seedling stage, spraying it on the stems can control the growth of the top, promote the growth of the lower part of the seedling, control the height of the seedling, promote root growth, improve the quality of the seedlings [15]. High purity of alpha-sodium naphthalene acetate can reduce the premature flower and fruit abscission rate, promote flowering and fruit setting, effective improve resilience of crops (16-17). Zi-long zhang, et al., [18] found diethyl aminoethyl hexanoate can significantly promote the soluble protein content of rice seedling under low temperature stress. On the basis of reduction of MDA content, enhance activity of protective enzymes such as SOD and POD etc.. However, the application of plant growth regulators in banana planting seeding breeding, especially in cultivating of older banana provisional planting seedlings, has rarely been reported, and related researches haven't been seen. Long Yifei [7] and Zhang Xin-ling [8] study the effects of gibberellin and multi-effect azole on banana secondary seedling cultivation, and the study is limited to the growth index and index of nutrient, and hasn't referred to the study of planting seedling adverse resistance. Therefore, in this experiment, we select 5 kinds of common plant growth regulators, spray in the process of cultivation of older banana provisional planting seedlings, make comprehensive evaluation of effects of different plant growth regulators on the cultivation of older banana provisional planting seedlings, in order to select the appropriate regulators, banana provisional planting went to this experiment will provide theoretical basis for cultivating technology of older banana provisional planting seedlings. Experimental materials. The crops selected for experiment: a Brazilian breed banana transplanting seeding (six leaves and one shoot), provided by Seedling Tissue Culture Center of Chinese Academy of Tropical Agricultural Sciences; The basin selected: black nutrition cup (specification (straight stem x height) : 16 cm x 14 cm). The media selected: coconut chaff, physical and chemical properties of bulk density: 18.69 g/cm(3), total porosity: 79.65%, PH: 5.81, organic matter: 64.38%, alkali-hydrolyzable nitrogen: 357.42 mg/kg, rapid available phosphorus: 821.66 mg/kg, rapidly-available potassium: 28976.53 mg/kg. The fertilizers selected: urea (46% N), potassium chloride (K2O 60%), compound fertilizer (15-15-15). Plant growth regulators: gibberellin (GA3) (purity 98%), multi-effect azole (PP333) (purity 98%), Compound sodium nitrophenolate (98% purity), diethyl aminoethyl hexanoate (DA - 6) purity (98%), alpha-sodium naphthalene acetate (purity 98%). The method applied in the experiment. Use types of plant growth regulators as influence factors, set 5 processing approaches by using gibberellin, multi-effect azole, compound sodium nitrophenolate, diethyl aminoethyl hexanoate, alpha-sodium naphthalene acetate, use the crops that haven't handled plant growth regulator as the control group. Use Spraying concentration of plant growth regulator of 20 mg/L, evenly spraying on the front side to the back of leaves till the plant growth regulator becomes a water drop. When spraying, use plastic film to separate this processing procedure from the part that has been dealt with by other processing, to prevent cross contamination. For the control group that hasn't been sprayed by plant growth regulator, spray the same amount of water on it at the same time. Transplant the seedlings on July 9, 2015. After the seedlings recuperate, do a treatment every 12 days, for a total of 5 times. 7 days after each treatment, measure the growth indexes. Set 15 banana planting seedlings for a group to observe, make a measurement every 10 days. On September 25, the banana planting seedlings have basically reached the standard of the older seedlings (with 13 similar to 15 of leaves) [19], when we make a unified recovery. Seeding sampling includes the sampling above the ground and the underground sampling; 9 older banana planting seedlings that are healthy and evenly growing, are randomly selected for sampling. then select mesophyll of the top second leave that has fully expanded, wrapped with aluminum foil, preserve it under the ultra-low temperature condition of - 80 degrees C after being frozen by liquid nitrogen, which is used for the determination of physiological indexes.nitrophenolate and diethyl aminoethyl hexanoate, these three kinds of growth regulators have different effects on the growth and physiological resistance, only specific aspects, which are not as significant as gibberellin and alpha-sodium naphthalene acetate. In summary, the results show that, during cultivating the older planting banana seedlings, spraying a certain concentration of gibberellin on the leaf, can increase the stem height, increase chlorophyll content, promote its morphology formation, improve resistances of the older banana planting seedlings; Spraying alpha-sodium naphthalene acetate can improve the strong older seedling index and promote dry matter cumulant and nutrient uptake. Thus, during cultivating the older planting banana seedlings, only spraying gibberellin or alpha-sodium naphthalene acetate separately can can have some effects; however, In order to get strong banana older planting banana seedlings, we should consider to mix gibberellin with alpha-sodium naphthalene acetate, or spray them at certain intervals. As for the effects of specific spraying, more further researches are still needed.
