Volume 92, Issue 3
June 1983, pages 233-311
pp 233-258 June 1983
Twenty one taxa of the genusLindsaea Dryand. ex Smith (including two new species, five new records and a new name) are described and their distribution indicat ed. Key to Indian subgenera, sections and species together with illustrations is provided to facilitate identification.
pp 259-264 June 1983
An allotriploid ofP. orientale Rich with 2n=27 chromosomes was located. Cytomorphological studies revealed that it is a new chromosomal race exhibiting chromosomal numerical mosaicism and neo-centric activity. Heterochromatic knobs present on the chromosomes are considered as sites of neo-centromeres. The possible causes of chromosomal mosaicism and neo-centric activity are discussed. Polyploidy coupled with hybridization seems to play a major role in the evolution of this taxon and the aberrant meiotic behaviour is not a barrier for the survival of the species since it is an apomict.
pp 265-269 June 1983
Sugarcane var. CO 740 is known to be salt-sensitive. Effect of increasing concentrations of NaCl and Na2SO4 as prolonged salt stress, and of −10 bar NaCl and PEG as well as 10 EC NaCl Na2SO4, MgCl2 and MgSO4 as abrupt stress in base-nutrient solution has been investigated on proline metabolism. Neither of these stress conditions could effectively stimulate proline accumulation in the leaves of treated sugarcane plants, in spite of the abrupt drop in leaf osmotic potential. It can be concluded that the sugarcane var. CO 740 lacks this adaptive mechanism and hence seems to be salt-sensitive.
pp 271-278 June 1983
A susceptibility ratio for identifying and rating resistance is suggested and compared with the present method under natural conditions of infection in the field. This ratio brings out rolative resistance as susceptibility of a test variety; the advantage is that rating for each variety remains stable under varied conditions of natural infection. According to the suggested system susceptibility ratios of 0.14 and 0.35 are regarded as resistant and moderately resistant respectively. Four models of visual resistance scale are prepared to directly denote susceptible, resistant and moderately resistant reactions under different disease pressures.
pp 279-283 June 1983
Seedling handedness with regard to first seedling leaf above the coleoptile has been studied in 67 genera and 93 species spread over 11 tribes of Gramineae. In general the tribes Paniceae, Andropogoneae, Festuceae, Hordeae, Aveneae, Bambuseae, Oryzeae and Chlorideae show seedling handedness whereas it is absent in Agrostideae, Phalarideae and Poaceae. Some tribes contain species that show handedness. Seedling handedness may be used for taxonomic purposes for delimiting the various tribes of Gramineae.
pp 285-296 June 1983
Structure and development of stomata have been studied in 14 genera and 22 species of the Acanthaceae. The leaves ofNeuracanthus sphaerostachys are hypostomatic while those of other species investigated are amphistomatic. The stomata are typically diacytic, monocyclic or incompletely or completely amphicyclic being surrounded by 2,3 or 4 subsidiary cells and mesogenous in development having been formed as a result of three, four or five successive mitotic divisions of the meristemoid. Arrested developments, single guard cells with or without pore, contiguous stomata and aborted guard cells are the common abnormalities noticed.
pp 297-301 June 1983
The effect of water stress on nodulation and nitrogenase activity of guar (Cyamopsis tetragonoloba (L.) Taub.) was studied at both vegetative and flowering stages. Stress did not induce any change in the nodule number but caused a significant reduction in nodule fresh weight. Drought-induced reduction in nitrogenase activity was observed at both the stages. Upon rewatering, rapid recovery in the activity was noticed which seems to be related to the adaptation of this legume to and regions.
pp 303-311 June 1983
Seedling vasculature and organization of primary vascular system ofC. foetidissima HBK has been studied. The nature of hypocotyledonary, cotyledonary and epicotyledonary traces has been discussed. Vascular interrelationships among leaves and also with tendril have been traced. The behaviour of the traces in cotyledonary and foliage petiole has been studied. Venation pattern and nature and frequency of stomata are discussed.