Studies on the Growth Characteristics and Fruiting Physiology of Grafted Papaya (Carica papaya L.)
| Autor: | Li- Hung Chiu, 邱禮弘 |
|---|---|
| Rok vydání: | 2004 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 The objectives of this study were to investigate nutrient absorption of selected rootstocks and grafted papaya plants, to examine the effect of plant growth regulators on axillary shoot growth and to evaluate the performance of grafted plant with scions taken from different portion of the tree. The ultimate goal is to develop an effective and convenient method of papaya propagation. Four papaya rootstocks, ''Philippines wild'', ''Jam Pa Da'', ''Da Moc'' and ''Tainung No.2'' (''TN2''), with flood tolerance were collected. In a container experiment conducted under structure, no difference was found in mineral element contents and dry weights between grafted papaya plants in which TN2 was used as scion and flood tolerant varieties were used as rootstocks. Same results were obtained when ''TN2'' seedlings and ''TN2'' grafted were compared. This indicated that grafting was unlikely to affect the nutrient uptake of grafted plants. In order to stimulate the multiplication and growth of axillary shoots of papaya, experiments of defoliation, sloping plant treatment, temperature treatments and applying plant growth regulators of different concentrations were conducted. Results showed that defoliation enhanced axillary bud sprouting; sloping plant treatment had normal level of axillary bud sprouting; temperature treatments affected the axillary bud sprouting percentage, the number of sprouting buds per node, and the length of lateral shoot. The stimulation effects had no significant difference between treatments of 32℃ and 27℃, yet both were better than 22℃ treatment. In the plant growth regulator experiments, BA treatment did not increase the length of lateral shoots, but GA3 did at 100ppm and 200ppm and both concentrations produced the same effect. Both BA and GA3 exerted their influence on bud sprouting percentage regardless of concentration. Application of GA3 200ppm increased the number of sprouting buds per node and produced more favorable results than the GA3 100 ppm treatment did. GA3 also promoted multiple bud proliferation. Results of potted experiment was indicated that the treatment of BA 200ppm plus GA3 200 ppm was the most favorable combination to stimulate the growth of lateral shoots. Practical field experiment on fully developed plants showed that BA 200 ppm plus GA3 100 ppm had the best bud sprouting percentage per node. In terms of mass production, spraying plants with BA 200ppm plus GA3 100ppm could produce an average of 3.7 scions per node in 45 days. Grafted papayas reduced the plant height; the node number, internode length and the area of grafted union cross section were significantly less than seedling. No differences were found in plant height, node number and length of internodes in the grafted papaya of different rootstocks. This suggested that the scion rather than the rootstock was the main factor of influence. The first fruiting position merely 33-39 cm above the ground, far lower than the 112 cm in the case of the seedling. Investigating the growth and development of one-year-old grafted plant, it was found that grafted plants with ''Da Moc'' and ''TN2'' as rootstocks had the largest cross section area of grafted union. Because of scions on ''TN2'' produced the tallest plants whereas those grafted onto ''Da Moc'' had the shortest and sturdy plants. However, scions grafted on different rootstocks exhibited marked effect on dwarfing in the field. This serves to show that grafted plants are suitable for net-house culture. Leaf area and leaf dry weight of grafted plant were stabilized when leaf nodal order were up to about 30-35th. Stabilization of seedlings was not detectable until their leaf node reached 55th. In the development of leaf node of respective treatment, leaf area and dry weight were found higher in the lower portion of grafted plants, which equaled those of seedlings with the leaf node level of 55th indicated grafted plants though dwarfed yet possessed higher biosynthetic activity at an earlier stage. In terms of yield, ''Da Moc'' and ''TN2'' rootstocks produced greater number of fruits, significantly more than any other treatments. Due to the dwarfing effect of grafting, the yields of grafted plants were potentially higher than that of seedlings. The absorption capacity of scion portion between TN2 self-grafted plants and TN2 seedlings was similar, and the dry matter also similarity among the four rootstocks. Chlorophyll content was found higher in grafted plants than in seedlings only under low temperature condition. The significance of the phenomenon merits further investigation. Using the scions from lateral shoot tip of the different stem portion to study the topohysis, the results showed there were much in correspondence between the degree of mature stage of the grafted plants and the scions from which original cutting were obtained. In conclusion, the grafted plant of papaya was not lowered the absorption of nutrient elements, yet had the shortened and sturdy plants. Carelly selection of scion reduced the plant height, lowered the bearing position and promised an early harvest with higher yield of fruits. Spraying plants with BA 200ppm plus GA3 100ppm was a very convenient method to forcing propagation of scions. Because of the well combinated capacity of papaya between rootstock and scion, the best choice of rootstock/scion combinations dependent on the requirements of culture purpose. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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