Study On Reproductive Biology Of Tamarindus Indica L.

Tamarindus indica L.,a single species of the Leguminosae genus Tamarindus,is a tropical evergreen fruit tree whose fruits have many uses in daily life,industrial food and medicine,and is considered the most valuable part of T.indica.As a newly-introduced species,T.indica has always had the problem of large flowering,but low seed setting rate and low fruit yield during the planting process.This paper systematically studied the sexual reproductive process and breeding system characteristics of T.indica,which was introduced from Yuanjiang Test Station,Institute of Resource Insects,Chinese Academy of Forestry,Kunming,Yunnan Province,and cultivated in Thailand.Preliminarily discussed the reproductive biological characteristics of T.indica,in order to enrich the reproductive biology data of Tamarindus,provide a scientific theoretical basis for the systematic classification of T.indica,and to reveal the weak links in the reproductive process for subsequent high yield and management the measures laid a theoretical foundation.The main research conclusions are as follows:(1)The whole flowering phase of T.indica begins in late April and ends in early October,with the peak flowering stage from June to July;the average individual flowering duration is about 28.90 d,and the blooming period is July;the inflorescence length is 15.377 cm,and the inflorescence blooming duration is 47.33 d;the flowering time of a single flower lasts from3:00 in the morning to 7:00 in the morning,and the flowering duration is 2～3 d,but most of them can only last for 1 d.At the population level,there is obvious asynchrony in the flower opening of the T.indica.This flowering mode is a continuous flowering mode.The number of T.indica inflorescence flowers,the duration of flowering and the final flowering period have a very significant positive correlation with the seed setting rate of the T.indica.The results showed that the later the final flowering period of tamarind,the longer the flowering phase and the more quantity,the higher the seed fruiting rate.(2)T.indica 3 stamens,the anther is four pollen sac,tapetum is deformable,mature pollen grain is 2-cell pollen,3 germ furrows,and the outer wall of pollen grains was closely crisscross arranged;ovary is one locular,double integument,thick nucellus,Polygonum type embryo sac,mature embryo sac synergids degenerates,antipodal cells degenerate early.The embryo sac develops normally,and the pollen undergoes nuclear degradation,cytoplasmic concentration and cell shrinkage during the development process,and the pollen sac has empty cells.The embryological characteristics of T.indica are both relatively primitive and relatively evolutionary.It is considered that Tamarindus belongs to the transition group from primitive to evolutionary in Leguminosae.(3)The breeding system of T.indica belongs to the mixed mating type with outcrossing as the main type.It has self-incompatibility and obvious characteristics of dichogamy,showing that the pistil matures first.The flower morphology has the typical comprehensive characteristics of entomophilous flower pollination.The main effective flower visitors are Apis cerana subsp and Apis florea Fabricius.(4)Reasons for the low natural fruit setting rate of T.indica: T.indica have low self-incompatibility.The germination rate of self-pollen on the stigma is low.It is difficult for the pollen tube to enter the style.Occasionally,the pollen tube that enters the style grows slowly or stops growing;Secondly,the tapetum grows abnormally during the embryonic development of the T.indica,and the degradation delay makes it impossible to absorb enough nutrients to form mature pollen grains during the pollen development process,which causes pollen abortion and reduces the number of pollen;At the same time,the flowering period of a single flower is short,and the amount of stigma pollen adhesion is completely dependent on the foraging behavior of the pollinator.The activities and behaviors of visiting flowers are easily affected by the circumstances,and the number of visiting a flower in a certain period of time is comparatively low,which limits the number of T.indica pollen,so that the blooming flower not get pollen or enough pollen in the best pollination period,hinder its fertilization,and affect the fruit setting.