Volume 68, Issue 4
October 1968, pages 169-220
pp 169-174 October 1968
The two isolates (F 1 and F 2) ofFusarium solani responsible for lime twig disease were tested for their trace element requirements. The effect of zinc, iron, copper and manganese singly and in all possible combinations on growth and sporulation of the two isolates was studied and it was found that in both of them iron and zinc, singly and in all combinations, played a remarkable role. Best growth and sporulation took place where the medium was supplemented with a combination of zinc, manganese and iron. Copper either singly or in mixtures was less effective for sporulation while zinc had a key role in this process.
pp 175-180 October 1968
In this brief paper are enumerated sixteen species of fungi collected and isolated fromTypha angustata, of which fifteen are new host records.Mycosphaerella typhira has been described as a new species with illustration.
pp 181-189 October 1968
Two chemical mutagens, namely, pyrogallol and pyrocatechol were employed to induce variability in some of the production traits in sugarcane such as the number of internodes, girth of the internode and brix per cent. Two concentrations under each mutagen were used and their effects were compared with the control in theνM2 generation. The results indicated the absence of gross morphological changes, but induction of a wide spectrum of variability very characteristic of polygenic mutations. The mutagenic effects were positive in the case of number of internodes and brix content and negative in respect of girth. Very high transgressive variants on the positive side were obtained and selected for further studies. Consequent to the induction of micromutations through chemical mutagenesis, the scope for improvement of sugar per acre seems promising.
pp 190-201 October 1968
Genetic analysis through diallel cross techniques reveal that length of peduncle, density of grain, diameter of peduncle and surface area of primary ear were under the influence of both intra-allelic and inter-allelic interactions. The interaction with regard to the first two characters could be identified as complementary type. Yield of primary ear was found to be conditioned by complementary genes besides some additive factors. Both epistasis and overdominance were found responsible for the observed heterosis in respect of peduncle characters and density of grain. In cases of surface area and yield of primary ear, epistasis alone accounted for the manifest hybrid vigour. In the light of the genetic situations investigated, the characters are discussed for their breeding implication.
pp 202-205 October 1968
pp 206-209 October 1968
pp 210-220 October 1968
Genetic analysis of some quantitative traits of pearl millet through diallel cross techniques revealed that (i) plant height was governed by complementary and overdominance genes; (ii) Tillering capacity by dominant and complementary genes; (iii) yield of straw by overdominance and epistatic genes and (iv) yield of grain by genes with additive overdominant and epistatic effects. Both complementary and overdominant genes were found responsible for the observed heterosis in respect of plant height, whereas epistasis alone caused heterotic effects with regard to tillering capacity and yield of grain. In case of yield of straw, both epistasis and excess of positive recessives accounted for the augmented F1 vigour. In the light of genetic situations investigated the characters have been discussed for their breeding implications.