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Nutritional Status and Productivity of Carabao Mango (Manglfera Indica L.) Trees Induced Regularly with Potassium Nitrate as Influenced by Fertilizer and Indole Acetic Acid Application
Dissertation Abstract:
The study was conducted to determine the nutritional status and productivity of Carabao mango (Mangifera indica L.) trees regularly induced with potassium nitrate when fertilized and appl ied with indole acetic acid (IAA).
The treatments evaluated were: zinc (Zn) and calcium (Ca) application; nitrogen (N), phosphorus (P), and potassium (K) (NPK) levels 0-0-0. 0.4-0.4-0.0, and 0.8-0.8-0.8 kg N- Pp5,-Kp per tree; and IAA application. The experimental trees were 35 years old and induced regularly with potassium nitrate.
Significant interaction effects were observed on the number of fruits and yield per tree. The trees applied with Zn (0.5 kg ZnSO/tree) and 0.8-0.8-0.8 kg NPK but not sprayed with IAA produced the highest number of fruits (1,176.5) and fruit yield (214.70 kg) per tree. The trees applied with Ca without NPK but sprayed with IAA registered significantly the least number of fruits (22.5) and the lowest yield (4.7 kg per tree). The application ofNPK significant ly increased the pH of ripe fruits from 4.77 in the control (0-0-0) to 4.96 and 4.98 in those applied with 0.8-0.8-0.8 and 0.4-0.4-0.0 kg NPK/tree, respectively.
However, the application of different levels of NPK, Zn and Ca did not increase significantly the level of N, P, K, Ca, magnesium (Mg), Zn, copper (Cu), manganese (Mn), and iron (Fe) contents of the leaves at flower induction and after harvest.
A significant increase in N. P, K, Zn, and Cu contents of the leaves were observed from fertilizer application to flower induction; but the level of N, K, and Cu atlcr harvest did not differ significantly from that before fertilizer application. The Mg level after harvest was significantly lower than before fertilizer application. On the other hand, Ca and Fe contents before fertilizer application were significantly higher than at flower induction and after harvest.
A significant positive correlation was observed between fruit yield and percentage of flowering, length of panicles, number of fruits retained per 50 panicles, and number of fruits per tree. The total K and Cu content of the leaves at flower induction was significantly and positively correlated with the percentage of flowering and number of fruitlets per panicle, respectively.
The N uptake was closely associated with K and Ca uptakes. A direct and significant relationship was noted between Zn and Cu, and Mg and Fe as regards their uptake. The Zn and Cu uptakes were inversely and significantly correlated with Ca uptake. Also, the total carbon (C) content was positively and significantly correlated with the starch and total N content of the leaves at flower induction. An inverse and significant relationship was found between C/N ratio and total C and total N contents of the leaves at flower induction.
The trees applied with 0.8-0.8-0.8 kg NPK per tree removed the highest amount ofN, P, K, Ca, Mg, Zn, Cu, Mn, and Fe. The control trees removed the lowest amount of nutrient elements. Regardless of NPK levels, the nutrient removals were in the following order: K, N, P, Ca, Mg, Fe, Zn, Cu, and Mn.