HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Chung, N.-J. Articles by Paek, N.-C. Search for Related Content PubMed Articles by Chung, N.-J. Articles by Paek, N.-C. Agricola Articles by Chung, N.-J. Articles by Paek, N.-C. Related Collections Rice Seed Establishment

SEED

Photoblastism and Ecophysiology of Seed Germination in Weedy Rice

^a Natl. Crop Exp. Station, RDA, Suwon 441-100, Korea
^b School of Plant Sci., Seoul Natl. Univ., Suwon 441-744, Korea

* Corresponding author (ncpaek{at}plaza.snu.ac.kr)

Received for publication February 12, 2002. The germination of rice (Oryza sativa L.) seed has been known to be unaffected by light or darkness, but a photoblastic rice (PBR) whose germination was favored by light was discovered in weedy rice. The effects of light, temperature, and soil burial depth on the seed dormancy and germination of PBR were examined. At 30°C, the seeds germinated 100% under white or red (R) light and below 1% in darkness. They showed 67 and 20% of germination under continuous and a brief pulse of far-red (FR) light, respectively, and photoreversible germination under alternating irradiation of R and FR light, indicating that the induction of germination occurs through very-low-fluence response and low-fluence response of phytochromes. The prompt and delayed induction of germination by a pulse of R and FR light, respectively, following dark imbibition suggests that phytochrome B exists in dormant seeds and phytochrome A is synthesized during dark imbibition. Dark imbibition for longer than 3 d induced secondary dormancy. In darkness, the germination frequency was about 28% at 15 to 20°C and below 1% at 25 to 40°C. At 12 h-diurnal fluctuations of 20 and 10°C and 25 and 15°C in darkness, the germination frequencies were 77 and 27%, respectively. When the seeds were sown in the soil, emergence frequency decreased as burial depth increased, and 12-h diurnal fluctuation of 20 and 10°C induced more seedling emergence than constant 15°C. Conclusively, PBR seeds are capable of germinating by sensing light or proximity to the soil surface during seasonal fluctuations in diurnal temperatures.

Abbreviations: ABA, abscisic acid • DAI, days after imbibition • FR, far red (light) • GA, gibberellic acid • PBR, photoblastic rice • Pfr, far-red-light–absorbing phytochrome • phyA, phytochrome A • phyB, phytochrome B • Pr, red light–absorbing phytochrome • R, red (light)