Effects of pinching on flowering and fruiting habits of Vinca rosea L

Abstract

This study was carried out to obtain basic data on the seed production of florist crop in Tohoku region aiming the improvement of seed producing technique. Annual vnca (Vinca rosea L, var. Kermesiana) was used as the material, and its flower-ing and fruiting habits were observed comparing intact plants with pinched ones. In this experiment, the seeds were sown on the May 24 1957. The results are summarized as follows:
(1) The anthesis began in early August and reached the maximum in early September. And, it continued until the frosting season, but decreased extremely after early October.
(2) The anthesis on the uppermost branch was observed about two weeks later than that on the main stem. It was delayed gradually according to the height of branches downwards. On the lowest branch, a delay of three weeks was recorded.
(3) The tendency was recognized that the lateral branches, on which flowers opened succes-sively during from late August to early September, showed uniform growth as the result of pinching the main stem. The pinched plant produced flowers twice as many as the intact one.
(4) Seeds could be harvested from the flowers opened by early September, but not later. A consi-derable amount of seed pods could be gathered from the pinched plant in one harvest. Hence, therefore, the labour for seed production may be saved by pinching.