Volume 14, Issue 1
July 1941, pages 1-73
pp 1-16 July 1941
pp 17-24 July 1941
This paper presents a study of thePara-sorghums consisting of four species, namelyS. purpureo- sericeum, S. dimidiatum, S. versicolor andS. nitidum. The group is characterised by the hairiness of the plants, bearded nodes, very long awns (upto 40 mm.) and five pairs of chromosomes.S. purpureosericeum andS. dimidiatum are very closely related to each other, but for the slightly reduced and half coriaceous glume of the latter. The difference is brought about by a single gene.S. versicolor andS. nitidum are more closely related to each other than to the other two. The sorghums of this group do not have much value as fodder in South-India, as they are unable to with-stand cuttings and succumb to the least disturbance to the root system.
pp 25-34 July 1941
A spontaneously occurring haploid plant in one of the open-pollinated cultures oftoria is described for the first time.
The haploid was a reduced replica of the diploid plant with smaller leaves and flowers. It flowered at the same time as the diploid and after setting a good amount of seed under conditions of open-pollination died with the rest of its sister plants.
The somatic chromosome number of the haploid was determined in meristematic cells of young leaves as 10 and that of the diploid as 20. A few cells with the diploid number of chromosomes were found scattered in the leaf tissue of the haploid.
At meiosis, the haploid showed 10 univalents from diakinesis to anaphase I in each pollen mother cell, Occasionally, however, a loosely paired bivalent was noticed in some cells. At division I the univalents either segregated at random into two groups or collected to form an interphase nucleus. Division II in the former case produced tetrads of unequal spores, and in the latter dyads of equal spores.
A few pollen mother cells with the diploid number of chromosomes were also noticed in the haploid ; these were seen to undergo normal meiosis producing tetrads with equal spores.
As a result of dyad formation in a large number of haploid pollen mother cells and tetrad formation in the few diploid pollen mother cells, the pollen fertility of the haploid was found to be as high as about 60 per cent. Seed-setting in the haploid was also fairly high under conditions of open and cross-pollination. The possible utilisation of haploidy in practical breeding is discussed.
pp 35-46 July 1941
The development of microsporangium inNicotiana glutinosa is described. Fusion of the tapetal nuclei has been recorded.
A comparative study of the embryo-sac and embryo formation inN. glutinosa andN. tabacum, the two parents of the present hybrid, has been made.
The development and behaviour of the megaspore in the hybrid is described and compared with that of the parents.
pp 47-67 July 1941
The prevalence of hot and dry winds during the development retard the growth in size of the grain and cause its desiccation with the result that it gets shrivelled and there is a decline in yield. The grain is much reduced in size and is deficient in food store.
It has been substantiated by experiments that germination power and suitability of shrivelled grains for sowing are not affected.
The progeny plants of shrivelled grains lag behind the plump grains in growth in early stages of development, but the initial differences disappear at a later period. Ultimately shrivelled grains produce a crop as good as obtained from plump and normal grains.
The seedlings produced by shrivelled grains are metabolically less active than plump grain and lag behind considerably throughout the germination period.
The initial lower weight and smaller size of the shrivelled grains do not operate adversely on the subsequent process of growth and yield of the crop.
The shrivelled grains produce a normal crop of well developed grains and the progeny grains show an increase of 212.2 per cent, in weight over the parent grains.
It is shown that there is no advantage in grading wheat in order to get increased yield in the produce of pure line.
pp 68-73 July 1941