Abstract

Selection and evaluation of plus trees through progeny trials are crucial steps in genetic improvement programmes. Half sib or full sib progeny trials allow the use of additive gene effects and hence, new recombinants can be identified and thereby paving way for further improvement. A progeny trial plot was established under the present study at Nilambur with 64 families (progenies of 64 plus trees) to evaluate the breeding value of these plus trees. The trial was monitored for growth up to the age of five years after field planting. The results of the present study revealed that there is no influence of geographical origin of the families on growth performance. With respect to girth at breast height, the best cluster of families comprised progenies of plus trees T4, 6 and 24 from Nilambur, 19,136 and 137 from Konni, 105 and 106 from Kannavam, 48 and 150 from Arienkavu, 50 and 104 from Wynad and 121 from Parambikulam. The phenotypic and genotypic coefficients of variation as well as family heritability were moderate for height and girth in general. The progeny trial can accomplish the purpose of a seed orchard after removing the poor trees and allowing a minimum of 10m spacing between trees. The present study conducted using microsatellite markers, to determine the genetic similarity between plus tree clones and to exclude close relatives in further improvement programmes, showed possibility of demarcation of various clones from each other even with two microsatellite markers except in two clones where three markers were necessary. The study also showed good genetic variability between clones. The clustering of ten clones revealed that all the clones from Arienkavu belonged to one group. Clone T20 from Konni was closer to Arienkavu clones rather than Nilambur clones. Plus tree clones T1 and T10 from Nilambur formed one cluster while T3 from Nilambur stood separately.