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STUDIES ON THE GERMINATION OF SEEDS OF THE ROOT PARASITES, ALECTRA VOGELII AND STRIGA GESNERIOIDES. I. ANATOMICAL CHANGES IN THE EMBRYOS
Author(s) -
Okonkwo S. N. C.,
Raghavan V.
Publication year - 1982
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1982.tb13416.x
Subject(s) - radicle , biology , germination , vigna , botany , striga , meristem , shoot , horticulture
Anatomical changes in the radicle and shoot meristems of embryos of germinating seeds of the obligate root parasites, Alectra vogelii and Striga gesnerioides were studied. When germination of seeds was stimulated by cowpea ( Vigna unguiculata ) root exudate, growth occurred mainly in the radicular pole of embryos and minimally in the plumular pole, resulting in seedlings with elongated radicles. Maximum radicle elongations of about 3 mm in A. vogelii and 2 mm in S. gesnerioides were recorded during a period of 8 and 11 days, respectively. Analysis of the radicular tip during the course of seed germination revealed that the activity of the meristematic tissue progressively decreased until it completely disappeared. When germinated seeds were cultured on nutrient agar media, the radicle meristem of A. vogelii continued to grow producing a normal root with a root cap. On the other hand, the radicles of cultured S. gesnerioides seeds elongated only slightly before meristematic activity ceased. During continued growth of seedlings of both species on agar media, lateral roots whose tips had typical angiosperm root topography, were initiated from the radicle.