GIBBERELLIC ACID, CEPA, AND UREA ON FLOWERING INDUCTION AND FRUIT YIELD OF ?VALENCIA? ORANGE
A study was carried out on seven-year old ?Valencia? orange trees, growing in a clay loam soil to shift the harvesting period from January-March (normal) to May-August when fruit gets the highest price. GA3 25 mg L-1 was applied twice (December 12th and 26th, 1990) to reduce the late winter flowering. In addition, at 80 % of petal fall, CEPA 1000 mL L-1 + urea 2 % was sprayed to reduce fruit number (March, 1991). To stimulate summer flowering, CEPA 250 mL L-1 was applied in mid-April, when fruitlets diameter was 1.5 cm, together with low-biuret urea at the rate of 210 g N per tree divided in two applications: 60 g on April 23 and 150 g on May 29. These treatments were applied before the completion of natural soil moisture stress. In winter as a result of GA3 treatment, the number of flowers and shoots per m2 of canopy decreased in 24 and 28 %, respectively. CEPA + urea in a 2nd stage, got 95 % of fruitlets thinning and further stimulated vegetative flushes and blooming in April, at levels four to five times greater than in control trees. However, strong defoliation and even shoot tip burning was observed in treated trees. Summer flowering intensity was increased because of the GA3 applied on December as well as the urea sprayed on April and May, but only urea increased summer production. Neither thinning of fruitlets, in winter, nor applying CEPA alone in April were effective in increasing the size of the spring and/or summer harvest.
| Main Authors: | , , |
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| Format: | Digital revista |
| Language: | spa |
| Published: |
Colegio de Postgraduados
1997
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| Online Access: | https://www.agrociencia-colpos.org/index.php/agrociencia/article/view/1493 |
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