Efeito da poda, raleio de frutos e uso de fitorreguladores na produ??o de tangerinas (Citrus deliciosa Tenore) cv. montenegrina

摘要

The experiment had the purpose to evaluate the effects of pruning, hand thinning and growth regulators sprays to decrease the production alternation and increase the physic-chemical quality of 'Montenegrina' mandarin oranges (Citrus deliciosa Tenore). They are plants budded on 'Caipira' Orange (Citrus sinensis L. Osbeck), and the present study was conducted in a six-year-old commercial orchard, in Panoramas Citrus Company, located in Butiá-RS, Southern of Brazil (29o57'S - 51o40'W). The following treatments were applied: A) Control 1, trees with heavy fruit load; B) Control 2, trees without bearing fruits; C) Hand thinning of 66% of the fruits on heavy loaded trees, in February; D) 200 mg L-1 Ethrel sprays of heavy loaded trees; E) Pruning of heavy loaded trees in December; F) Pruning of heavy loaded trees plus hand thinning in 33% of the fruit; G) Pruning of heavy loaded trees plus 50 mg L-1 of 2,4-DP sprays (95% of 2,4 dichlorofenoxipropionic), at the end of the natural fruit fall in December; H) Pruning of alternate bearing trees in December; I) Pruning of alternate bearing trees plus 10 mg L-1 GA3 giberelic acid sprays (10% of AG3) in May. The treatments were applied in a randomized blocks design with 4 replicates and 3 plants as experimental unit. Pruning decreased the production in each plant in a year of excessive fruit quality, and diminished the alternate bearing of trees associated to the hand thinning practice of 33% of the fruits. In alternate plants, the hand thinning was more efficient to break the production alternation. Hand thinning and pruning of 66% increases the mean mass and better the fruit quality, but the hand thinning of 66% of the fruits was only enough to break the production alternation. Ethephon sprays showed no thinning effect with concentrations of 200 mg L-1 and 10 mg L-1 of GA3 sprays didn't inhibit bud flower differentiation and 50 mg L-1 2,4-DP sprays have no effect on increasing fruit size.