THE DEVELOPSIENT AND PROGENI(?) EXPRESSION OF SOME CHARACTERS IN THE TOMATO

Ting Tzun-Yong, Ging Shih-Hsi, Tan Gee-Mong

Experiments were carried out with more than 70 varieties and 30 cross combinationS over three years to Study the de elopment of Some characters in the tomato plant in shenyang area.The following primary conclnsions have Leen drawn: 1.Under the condition that seedlings are raised in hot bed and trans planted to the open in early May, the growth period from the time of sowing to first harvest requires about 135 days; and it can be subdivided into the following stages,namely,the gevmination stage (12.5±6.5 days), the seedling stage (29.5±5.5 days), the flower development stage (35±8 days), and the fruit development Stage including the flowering stage (58±10 days),Flower bud differentiation usually begins during the appearance of the fourth leaf.Within the growing season, the shortest growth period occurred white seed were sown in June, and under such condition the time required from seedling emergence to first harvest needs only 80 days. 2.Temperature is the main factor which influences the length of the second developmental stage, which is shorter with mean temperature above 20℃ than it is around 15℃.The main factor that influences the length of the third developmental stage is the intensity of light.The effect of other factors such as the daily mean temperature, deposition of rainfall and others within the range of seasonal variation seems to have only minor importance.With the fourth and fifth developmental stage, temperature is still the main influencing factor. 3.Earliness of maturity has been found to be dependent both upon the time of flowering and the length of fruit development period.Under ordinary cultural condition it depends more upon the length of fruit development period, while under condition unfavorable for flower bud differentiation it depends more upon the flowering time. 4.The position of the first inflorescence varies with the growth condition of seedlings, and its year-round curve (including greenhouse culture) appears to have two peaks, i.e.higher in Spring and Autumn sowing, lower in Summer and Winter Soving.This is also true with hybrid seedlings.It seems that under ordinary condition light intensity and the daily amplitude of temperature are the two main factors which affect the position of the first inflorescence. 5.No Significant correlation was found letween earliness and the position of first inflorescence.The Conventional hypothesis which postulates,the existence of this correlation calls for further consideration. 6.There is no significant correlation existing between the length of fruit development period and the size of fruit finally attained.The length of fruit development period seems to be determined mainly by the rate of development in early stage with mean temperature alove 20℃ which is found to be more rapid than that of 15℃.Fruits that have reached the size alout half of their final diameter require about 25 days for further develop ment to reach maturity under all experimental conditions.Tomato fruits reuire alout 800℃ of summation of mean daily ternperature to develop from fertilization to maturity.However, early varieties may be satisfied with temperature summation lower than this, while late varieties may require a little higher than this. 7.Continuous selection of the early ripening fruits from early maturing plants results in gradually tropping of the mean fruit weight. 8.when plants were prunned to set only with three trusses of fruits, the varietal difference expressed as average yield to the plant was found to have no significant correlation with the mean numler of fruits to the plant tut to depend mainly upon the mean frnit weight of the variety. 9.The distribution of yield within the harvesting period from June to August may roughly be expressed by a curve with only one peak.if the yield is counted by every ten days, then most varieties reach their highest yield at the third or fourth time of picking.Generally, the first three pickings have already yielded about 70—90% of their total products.Inorder to utilize the land more economically a harvesting period lasting 30—40 (lays should be considered as suitable. 10.Most F_1 hybrids are superior to the parents as regard to the earliness of maturity, proluctivity, and high yield on the early stage.Among the varieties which have been tested,"Bison","Bounty" and"podaleaskovsky" are better parents for prolucing early and productive F_1 hybrids.