THE INFLUENCE OF NAA-SPRAYS ON FLOWERING AND EARLINESS OF FIELDCUCUMBER

Laibach and Kribben (1950a, b) found that a treatment of cucumber plants with NAA (-naphtyleneacetic acid) in lanolin paste increased the number of pistillate flowers considerably, and decreased the number of staminate flowers. Ito and Saito (1957) reported that spraying of cucumber plants with NAA solution increased the number of pistillate flowers also under conditions of long day and high temperature, which factors normally decrease the number of pistillate flowers (Nitsch, Kurtz, Liverman and Went, 1952).

Borkowski (1966a, b) found that two sprays of NAA solution significantly increased the number of pistillate flowers in cucumber plants. Two sprays with 25 or 50 ppm of NAA applied when the seedlings were in the stage of 2–5 leaves increased the marketable yield with 9–48 kg/are. By using higher concentrations the number of pistillate flowers increased some times, but yield did not increase. It may be explained that higher concentrations of NAA retarded the growth of the plants. Borkowski (1966a and 1969) found that appearance of angular leaf spot (Pseudomonas lachrymans) on cucumber plants decreased considerably the profitable effect of NAA on the yield. The angular leaf spot appears on cucumber crops in Poland almost every year, so the NAA-application to increase cucumber yield does not always give a good effect.

This paper presents the problem of acceleration of the fruiting-time of cucumber by NAA sprays.