Interspecific and Intergeneric Hybrids of Saccharum spontaneum L
I. Functioning of gametes
1961 年 26 巻 2 号 p. 117-123
詳細
1961 年 26 巻 2 号 p. 117-123
The paper relates to the observations made on the gametic contributions from the male and female sides in a number of intra and interspecific crosses in Saccharum and crosses with allied genera. The findings are as below:-
1. Chromosome numbers in all F1s of intraspecific crosses involving five S. spontaneum variants, namely, S. spontaneum (Coimbatore), S. spontaneum (Glagah), S. spontaneum (Holes I), S. spontaneum SES 248 and S. spontaneum S.H. 546 (Egypt) indicated functioning of only haploid gametes on the part of both the parents.
2. When S. spontaneum Coimbatore was selfed, a few giant forms with three times the haploid chromosome number of the parent were obtained in addition to a large number of diploid plants with n+n gametic constitution. The functioning of diploid egg gametes is therefore to be inferred in the former.
3. The species S. barberi and S. robustum were also found to contribute only haploid gametes in both way crosses with S. spontaneum variants. But, S. officinarum was generally found to contribute the diploid egg gametes in crosses with S. spontaneum, except when crossed with certain variants G. 3009-Uganda (2n=120) and S. spontaneum S. H. 445-Ceylon (2n=128).
4. In crosses between S. spontaneum and a few hybrid cane varieties having some spontaneum chromosomes in their genetical make up the functioning of only haploid gametes was observed. However, one instance of functioning of diploid egg gamete on the part of the pistil parent, POJ. 2725 and two cases, viz., Co. 421×S. spontaneum Coimbatore, Co. 421×S. spontaneum Glagah wherein egg gametes with a deficient haploid number had functioned were noticed.
5. Functioning of both 2n+n and n+n gametes was observed in interspecific as well as intergeneric crosses, viz., S. spontaneum×S. offacinarum and S. spontaneum×Sclerostachya, Narenga and Erianthus.
6. The functioning of n+n as well as 2n+n gametes was noticed in crosses between different varieties belonging to the same species and even in selfs. It would therefore, appear that gametic contribution is unsuitable as a criterion of genetic relationship between the types involved in crosses.
7. It may be possible to use the gametic contribution of a clone as, an additional criterion along with morphological and anatomical characters for identification of its species.
