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| Author(s): |
Wagner Rodrigues dos Santos
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 1997-12-02 |
| Advisor: | Ondino Cleante Bataglia |
| Abstract | |
The main objective of this work was to evaluate the Diagnosis and Recommendation Integrated System (DRIS) as a criteria for leaf analysis interpretation of macronutrients in citrus crop. The DRIS method was compared to the Sufficiency Range through yield responses to nutrient application. The DRIS method required the definition of a reference population for citrus. This was the criticaI point of this work since there is a lack of standard procedures for sample selection. The data of foliar analysis, soil analysis and fruit yield derived from a network of six fractional factorial N, P and K fertilizer experiments. Each experiment was established with 32 pIots with yearly rates of N (30, 100, 170 and 240 kg N/ha), P (20, 60, 100 and 140 kg P205/ha) and K(30, 110,190 and 270 kg K20/ha), divided in three applications throughout the raining period. These experiments were conducted from 1988 to 1993 on different soils of the citrus-producing regions of the State of São Paulo, Brazil. The behaviour of the macronutrient foliar contents was related to fruit yield through correlation analysis to study interactions among nutrients and among nutrients and fruit yield. DRIS indices interpretations of macronutrients were based on the assumption that negative values for a nutrient were limitations to yield while null or positive values were associated to sufficiency leveIs. Extremely high values were not verified as their criticaI effect on fruit yield. The comparison of the three computing procedures to calculate DRIS indices found in the literature and the Sufficiency Range was done by performance evaluation of nutritional equilibria diagnostic methods. The efficiency of each method was evaluated by accuracy index, ratio (V+:F+) and net yield response. The results of this study emphasized the need of a better defmition for the limits of nutrient contents on citrus leaves to use the Sufficiency Range method. DRIS methods were more responsive than the Sufficiency Range in the detection of potential yield responses. AIso, the DRIS was superior to defme oriented correction of possible nutritional imbalances. The procedure proposed by Jones was selected among the methods of calculating DRIS indices because ofits simplicity and ease ofuse. (AU) | |