Self and Cross Pollination in Mango

C. Degani                                A.R.O., Bet Dagan
R.J. Knighjt, R.J. Schnell       USDA-ARS, Miami
S. Gazit                                    The Heb. Univ. of Jerusalem

Project No. IS-1651-89; Duration: 3 years; Budget: $250.000

ABSTRACT

Bagging influorescences or caging trees (without bees) of the mango cultivars Irwin, Maya and 15-60 greatly decreased rate of pollination but did not prevent it completely. Thrips are not effective pollinators for mango. 'Irwin', 'Maya' and '15-60' responded differently to self-pollination under controlled pollination conditions. In 'Maya', 99.4% of the fruits produced on trees caged with bees were selfs and there was no significant difference in yield between caged and opened-pollinated 'Maya' trees. In 'Irwin', the yield in trees caged with bees was significantly lower than in open-pollinated trees and 98.6% of the regular fruits produced in the cages were selfs. In '15-60' the difference between yield in caged and open-pollinted trees was very large and the few fruits produced in the cages were hybrids. These results suggest that 'Maya' can set and carry a full crop by self-pollination, while 'Irwin' is partially self-incomatible and '15-60' is self-incompatible. The reciprocal effect of 'Maya' and 'Tommy Atkins' on the rate of hybrid percentage was studied in three commercial orchards consisting of two adjacent solid blocks of these cultivars. Rate of hybrids was determined using isozyme markers. Substantial hybrid percentage was found at large distances from the pollenizing cultivar. Studies on outcrossing rates during 'Tommy Atkins' fruit development showed a significant increase of hybrid percentage from the stage of fruitlets to the stage of mature fruit. This indicates selective abscission of selfed 'Tommy Atkins' fruitlets. RAPD markers were developed and used for detecting self- and cross-pollination, genetic relatedness and phylogenetic relationships in mango.