Biological and genetical aspects of reproductive system of mindi (Melia Azedarach Linn.)

Abstract

The study was aimed to determine biological and genetical aspects of reproductive system of mindi in relation to securing high quality of seeds. The study was conducted at four sites in West Java for the periods of 2009-2011. Direct observation over the trees (n=5-20 trees) were conducted on the periods of flowering and fruiting as well as floral morphology. Representative buds, flowers and fruits were sampled for microscopic dissection and reproductive study. The level of genetic diversities of maintained parental and produced offspring were evaluated either phenotipically or genotipically. Molecular characters were determined by using microsatellite markers. The genotipe deviation was evaluated based on Hardy-Weinberg and inbreeding structures. The observation revealed that floral initiation had proceeded for more than three months and the highest percentage of floral initiation occured in September. Reproductive cycle was proceeded for 5-6 months within the year, first observation commenced from generative buds to flower burst in September-October. Fruits reached maturity in January-February that took about 2-3 months after flower burst. The flower was hermaphroditic with position of anther was closed to stigma that selfing might be happened. Stigma receptivity lasted from 08.00 am to 11.00 am, rate of receptif was 66% in average, at 12.00 the receptivity was decreased to 40% and pollen viability was fluctuated from 4,89%-7,03% observed from 07.00 am-11.00 am. Controlled pollination exposed that mindi could be able to do both of cross- and self-pollination with the percentage of fruit set ranged of 70-77% and 42-57%, respectively. The genetic variation of mother trees and progenies for all loci and population were at range of 0,49-0,51 and 0,288-0,426, respectively. Genotipe deviation in progeny was detected at a small part of loci in two population with an average fixation index of -0,0680 and thus inbreeding might have been occured in a mating system of mindi in a low level. Assortative mating was detected in a very low degree. Three characters of seedling growth i.e length of bud, length of petiole and ratio of petiole to leaf length, might have to be used as keys to effective indicator for seedling selection.