Bio: Suresh Chand is an academic researcher from University of Calcutta. The author has contributed to research in topics: Nigella sativa & Callus. The author has an hindex of 3, co-authored 3 publications receiving 77 citations.
TL;DR: Callus cultures were obtained from seeds of Nigella sativa L. on a modified basal medium of Murashige and Koog (1962) and various cytological abnormalities like high and low chromosome number, stickiness, fragmentation, sticky bridges, lagging of chromosomes and multipolarity were observed.
Abstract: Callus cultures were obtained from seeds ofNigella sativa L. on a modified basal medium ofMurashige andSkoog (1962). Cytological studies were carried out from the tissues during different periods of growth. Various cytological abnormalities like high and low chromosome number, stickiness, fragmentation, sticky bridges, lagging of chromosomes and multipolarity were observed in all the passages. The way of elimination of extra chromatin material after long cultures has been pointed out.
TL;DR: Chromosomal abnormalities have been found to occur in maximum frequency where 2, 4-D is present in the media with kinetin.
Abstract: SUMMARYDifferent types of auxin like IAA, NAA and 2, 4-D in combination with kinetin have been used for the initiation and maintenance of tissues of Nigella sativa. Both the changes in growth pattern and cytological behaviour have been observed in all the cases. Chromosomal abnormalities have been found to occur in maximum frequency where 2, 4-D is present in the media with kinetin.
••07 Jul 2010
••01 Jan 2008
01 Jan 1992
TL;DR: This chapter attempts to provide a description of the structure of the potato plant, including both external morphology and internal anatomy, as well as investigating the development of the tuber.
Abstract: This chapter attempts to provide a description of the structure of the potato plant, including both external morphology and internal anatomy. Since the existing literature appeared to be particularly deficient on developmental aspects, some re-examination of early stages of development has been made where possible. Notwithstanding the considerable morphological and anatomical literature, it is clear that the structure and development of the potato, admittedly a very complex plant, are by no means fully understood; strangely enough, this applies particularly to the development of the tuber, despite its economic importance. There is considerable scope for further work in this field.
TL;DR: A zone of exine differentiation termed “region of weakness” is identified in Dacrydium colensoi, D.laxifolium, Podocarpus spicatus, and P.ferrugineus, the only modern trisaccate type in New Zealand.
Abstract: The pollen morphology of the New Zealand species of Dacrydium, Podocarpus, and Dacrycarpus is descnbed from observations made with the light microscope and scanning and transmission electron microscopes. An identification key is presented. Dacrydium pollen can be identified to the species level except for D. bidwillii and D. biforme which are inseparable. Podocarpus pollen is readily separated into two groups: (1) P. spicatus, P. ferrugineus and (2) P. totara, P. nivalis, P. hallii, P. acutifolius, P. totara var. waihoensis. Further identification, especially within group 2, is difficult. Dacrycarpus dacrydioides pollen is easily identified because it is the only modern trisaccate type in New Zealand. A zone of exine differentiation termed “region of weakness” is identified in Dacrydium colensoi, D. intermedium, D.laxifolium, Podocarpus spicatus, and P.ferrugineus. This region is adjacent to the proximal roots of the sacci at the lateral margins of the cappa and may function during periods of wat...
TL;DR: In this article, a potato canopy was divided into three horizontal layers of equal depth and defoliated at each layer, from the ground upward, on successive days, and the results indicated that the relative proportion of main or axillary-stem leaves are not as important for potato canopy modeling as is the need to simulate the correct quantity of leaf area.
Abstract: Mature potato (Solanum tuberosum L. cv. Kennebec) canopies are composed of leaves originating from main- and axillary-stem branches. Canopy leaf distribution and its corresponding contribution to wholecanopy photosynthetic rates have not been quantified. An experiment using SPAR (Soil–Plant–Atmosphere–Research) chambers maintained at 16-h day/night thermoperiods of 14/10, 17/12, 20/15, 23/18, 28/23, and 34/29C was conducted. Mature canopies were divided into three horizontal layers of equal depth. Canopies were defoliated at each layer, from the ground upward, on successive days. Response curves for photosynthetic rate vs. irradiance were obtained after each defoliation. Leaf area within each layer followed a quadratic relationship with temperature. The largest areas were between 16.6 and 22.1C. Main-stem leaves accounted for .50% of the total leaf area at temperatures ,22C, while the proportion of axillary-stem leaf area ineachlayerincreasedwithtemperature.Canopymaximumgrossphotosynthetic rates, AMAX, before harvest ranged from 9.5 to 34.8 mmol CO2 m 22 s 21 (production-area basis) and were higher at 14/10, 17/12, and 20/15C temperatures than at 23/18, 28/23, and 34/29C. These values were largely related to the quantity of leaf area in each chamber. The value of AMAX and canopy light use efficiency declined as successive canopy layers were removed, primarily due to decreases in canopy light interception. These results indicate that the relative proportion of main- or axillary-stem leaves are not as important for potato canopy modeling considerations as is the need to simulate the correct quantity of leaf area.