Effects of vernalization and photoperiod on the development of Chinese cabbage and mustards

Effects of vernalization and photoperiod on the development of Chinese cabbage and mustards

1957

REP.CC-0832

The present study was carried out both in the greenhouse and in the field, in Hangchow, China during 1954-1956, to investigate the effect of various treatments of vernalization and photoperiod on the flowering and vegetative growth of Chinese cabbage and mustards, and on the interaction of photoperiod and temperature. Chinese cabbage herein studied included both the headed varieties (Brassica pekinensis Rupr.), and non-head varieties (B. chinensis L.). The varieties of mustards (B. juncea Coss.) included those grown for their abundant radical leaves, and those for their swollen fleshyy roots or stems. They were collected from many geographic regions of China. The common cabbage (B. oleracea var. capitata L.) and Chinese kale (B. o. var acephala subvar. alboglabra Burkill) were also used in this study. The result showed that almost all the varieties herein studied of both Chinese cabbage and mustards may complete their stage of vernalization by low-temperature treatment of sprouted seeds. The varieties of each species, cabbage or mustard, may further be generally separated into "winter type" and "spring type" according to their responses to vernalization and photoperiod. The "spring" varieties may flower in the same season after seed sowing, without a definite period of low temperature treatment; while the "winter varieties have to pass through a definite period, generally 20-30 days, of vernalization treatment. The common cabbage did not produce flowers in the same growing season even if it had been exposed for a certain period to low temperature treatment either of the sprouted seeds or of the plants being too young to be affected by the treatment. The Chinese kale which taxonomically belongs to the same species of common cabbage, may produce flowers without low-temperature treatment under Hangchou condition. Obviousely, the plants which may complete their vernalization stage by the sprouted seeds, may also complete this stage by growing plants, but the reverse was not the case. The temperature favourable for the completion of vernalization of both Chinese cabbage and mustards was not very low. No appreciable differences were found in the number of days required to flower between the lots vernalized at 0-3 C, and those at 6-8 C. The duration of vernalization of the "winter" varieties of both Chinese cabbage and mustards lay between 20 and 40 days at 0-3 C. They would produce no flowers as the unvernalized seeds were sown on April 9, 1956, under Hangchow climatic and soil conditions. But the "spring" varieties of non-headed Chinese cabbage and mustards collected from South China, produced flowers in the same season after sowing, without any low-temperature treatment. The number of days required from seeding to flowering decreased with increasing the duration of vernalization from 5 to 60 days. But the influence by the duration of vernalization on the "spring" varieties was not so pronounced as on the "winter" varieties. Some varieties of Chinese cabbage was able to complete the stage of vernalization in 5 days at 0-3 C, while others were in need, of 20 to 30 days at least. All the varieties of Chinese cabbage and mustrad were found to be of long day plants. Flowering may be accelerateed by increasing the day length, but there were great differences of photoperiodic responses among different varieties. In one experiment carried out on 1956, the vernalized seeds of Tzu Tsai Tai (B. chinensis) and Hsueh Li Hung (B. juncea) sown on July 11, required much more days to flower than the sown on April 9. Apparently too high a temperture 30 C or more during the photoperiodic exposure may retard the flower develoment of both Chinese cabbage and mustard after vernalization treatment. Moderate cold nights (15-20 C) may accelerate the photostage. [AS]

v.6(1):7-28 (plates), ACTA BOTANIC SINICA

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