Factors responsible for the sex expression of Japanese cucumber. (IX)

Abstract

1. For the sake of the scientific and practical importance, in an attempt to learn about the effects of the nitrogen nutrition on the sex expression of the cucumber plant as influcnced by different levels of nitrogen application and soil moisture supply, ex-periments were conducted by means of sand culture with the following cultural solution: Salts Concentration NH4NO3 172.5mg/l N: 80ppm KH2PO4 181.9 P: 40 KCl 15.3 K:60.2 MgSO4.7 H2O 245.9 Ca(NO3)2 117.2 FeCl3 6H2O trace MnCl2.4H2O trace 2. The seedlings were raised under the varied day length and night temperature. Short day and low night temperature favor the pistillate flower formation. Under the short day and low night tem-perature, the effects of the differential nitrogen supply and watering on the female flower differen-tiation are masked. Under the long day and high night temperature, the female flower differentiation, being arrested by the day length and night temperature, further influenced by the nitrogen supply and watering. Abundant nitrogen supply arrests the female flower formation, especially in case of the restricted watering. 3. Soil moisture with moderate nitrogen level favor the plant growth. More abundant the mois-ture supply, more luxuriant is the plant growth. Under the low soil moisture condition, plant growth is arrested indifferent with the amount of the nitrogen supply. 4. The first female flower differentiates on the lower node with more abundant water supply and less nitrogen application. It seems that the number of nodes preceding the first female flower is reduced with the lower nitrogen level in plant. 5. Femal flowers successively differentiate seem-ingly accompanied by the restricted plant growth, under the differential nitrogen and moisture supply. The luxuriant growth is followed by the more nu-merous, staminate flower nodes preceding the ap-pearance of the succeeding female flower nodes. 6. Nitrogen percentage of the whole plant varies in accordance with the amount of the nitrogen app-lication. With more abundant moisture supply, in-vigorating the more luxuriant growth, the nitrogen percentage of the plant lowers regardless of being supplied even with the same amount of nitrogen by the cultural solution. 7. As above stated, lower nitrogen percentage is followed by the reduction of the number of nodes preceding the first female flower, and on the other hand, the luxuriant growth is followed by more numerous staminate flower nodes, hence it may be advisable for the practical grower to maintain mo-derate nitrogen supply and watering in the nursery, especiallg under the unfavorable day length and night temperature for the early pistillate flower differentiation.