Superior sweet oranges for varietal diversification of tropical rainfed orchards

Key words: Alternate bearing, Citrus sinensis, fruit quality, scions, vegetative growth, water deficit, yield. Citrus orchards in northeastern Brazil are mostly rainfed and comprised basically of 'Pera CNPMF D-6' sweet orange budded on 'Rangpur' lime, for the drought tolerance and productivity imparted by this rootstock. Therefore, the selection of new varieties is needed to broaden the genetic basis of citrus cultivated in this region. Accordingly, this study compared vegetative, productive, and fruit quality traits of eight sweet orange scions grafted on 'Rangpur' lime over eleven years under the tropical rainfed conditions of northeastern Brazil. 'Kona' trees excelled in yield performance associated with bulk canopy, precocity, sweet fruit with intermediate acidity, and high vitamin C contents in spite of proneness to alternate yields and low ratio (maturity index). 'Valencia Montemorelos' and 'Rubi' trees, in turn, had high yield performances coupled with intermediate canopies, sweet fruit, intermediate acidity ('Rubi') and vitamin C contents, low propensity for yield fluctuation ('Valencia Montemorelos'), and high precocity ('Rubi'), albeit low ratio. Overall, our results emphasize 'Kona,' 'Valencia Montemorelos,' and 'Rubi' as superior sweet orange varieties for diversification of tropical rainfed orchards for their outstanding yield performance and good fruit quality.