OUTCROSSING RATE IN ADJACENT MAYA AND TOMMY ATKINS MANGO BLOCKS

Outcrossing rate in mango (Mangifera indica L.) mature fruit was studi ed for the first time in an orchard consisting of two adjacent blocks of 'Maya' and 'Tommy Atkins'. Few polyembryonic rootstocks were detect ed in the blocks. Outcrossing rates were determined at different dista nces from the pollenizer block using the polymorphic enzyme systems tr iosephosphate isomerase and isocitrate dehydrogenase. The outcrossing rate was measured in 'Maya' for two consecutive years and in 'Tommy At kins' for one year. In all three cases, a pronounced decrease in hybri d rate was found between fruit sampled from the row bordering the seco nd cultivar and that from the most distant row sampled (108 m and 96 m for 'Maya' in 1992 and 1993, respectively, and 80 m for 'Tommy Atkins '). Outcrossing rates were: 63% and 34% for 'Maya' in 1992; 57% and 39 % for 'Maya' in 1993, and 79% and 24% for 'Tommy Atkins', for fruit sa mpled from the row closest to and most distant from the pollenizing cu ltivar, respectively. (C) 1997 Elsevier Science B.V.