Volume 98, Issue 5
October 1988, pages 317-424
pp 317-394 October 1988
Though about 120 taxa ofTrachelomonas and 13 taxa ofStrombomonas are recorded from the Indian region, only about 60 taxa have been described fully. These descriptions are scattered in different journals. The present account brings together 70 taxa ofTrachelomonas and 36 ofStrombomonas collected from north-east, central and south India during 1937–1976, with keys and figures for their identification.
Of these, 3 species ofTrachelomonas, viz.Trachelomonas costatus, Trachelomonas assamensis andTrachelomonas joysagarensis and 5 species ofStrombomonas, viz.Strombomonas hexagonalis, Strombomonas madraspatensis, Strombomonas vaseformis, Strombomonas indica andStrombomonas tortuosa are considered new. Sixteen varieties and forms ofTrachelomonas and 7 varieties and forms ofStrombomonas are also considered new. Nine species and 12 varieties ofTrachelomonas and 11 species and 7 varieties ofStrombomonas are new records for the Indian region.
A list of 87 taxa ofTrachelomonas and 7 ofStrombomonas, the major part of which are only just listed by various authors for the Indian region, are given at the end of each genus.
Some ecological observations onTrachelomonas andStrombomonas are given. The majority ofTrachelomonas species occurred in ponds with a fairly high degree of organic matter and fairly high nitrates and phosphates and low alkalinity during the rainless months of December to May.Strombomonas spp. were usually more common in ponds with higher alkalinity.Strombomonas verrucosa var.conspersa andTrachelomonas volvocina tolerated a wide range of total alkalinity. Excessive heat and sunlight or continuous rains seemed to have an adverse effect on the latter organism.
pp 395-398 October 1988
Launaea pinnatifida Cass. a member of the compositae, is a runner growing on sandy sea coasts of Indian subcontinent. The plant bears yellow flowered heads and produces milky latex. The cytological study with respect to its geographical distribution has been carried out. All the collections ofLaunaea pinnatifida showed 2n=18 chromosomes. Nine bivalents are counted at diakinesis. Meiosis is normal. One or two nucleolar bivalents are noticed. Position of centromeres in the chromosomes showed variation, this may be due to structural rearrangement taking place in the chromosomes of the taxon which has been discussed.
pp 399-403 October 1988
Early emergence was recorded inSchima khasiana as compared toPinus kesiya. However, initial seedling growth was higher in the latter. Better yield was recorded during monsoon in both the species. While inPinus kesiya shoot length increased up to the month of July and August, inSchima khasiana it continued up to September. The peak period for relative growth rate was recorded from August–September inPinus kesiya and September–October inSchima khasiana. It was concluded that the conditions prevalent at the study site during August (temperature 23·5/17·5°C) and September (temperature 22·5/14°C) under high humidity (80–90%) and moderate rainfall (400 mm) may be appropriate for growth of transplants ofPinus kesiya andSchima khasiana respectively, under controlled conditions.
pp 405-407 October 1988
Progenies of androgenetic doubled haploid plants of mustard cv TM-4 in A4−A6 generations were evaluated for their seed yield and oil content. Eight progenies in the A5 generation out of the 97 (8%) A1 plants regenerated were equal in yield to the parent cultivar. The oil percentage in these doubled haploids were in the same range as that of the parent cultivar. The remaining androgenetic doubled haploids were statistically lower in yield. The data indicates that about 8% of thein vitro raised androgenetic plant progenies had no adverse effects on yield potential and point to the need for obtaining a large number of androgenetic doubled haploids to recover genotypes more productive than the better parent.
pp 409-417 October 1988
Mature epidermis and stomatal ontogeny were studied in the leaves of 10 species (9 genera) belonging to Apocynaceae. Abaxial intercostal cells ofWrightia tinctoria are straight-walled and those of adaxial side inWrightia tinctoria, Cascabela thevetia andCarissa spinarum are sinuous. Adaxial epidermis ofRauvolfia tetraphylla is papillose. Hairs are thin-walled inPlumeria rubra (unicellular) andCarissa spinarum (uniseriate) and thick-walled inRauvolfia tetraphylla, Catharanthus roseus (uni- and multicellular) andCatharanthus pusillus (unicellular). Leaves ofWrightia tinctoria, Ervatamia divaricata andCatharanthus spp. are amphistomatic while those of other species are hypostomatic. Four stomatal types viz. anomo-, aniso-, tetra- and paracytic, occur in different combination patterns. Codominance of two stomatal types and their origin from unilabrate meristemoids isolateCatharanthus from other taxa. Its primitive nature is indicated by the unilabrate meristemoids.
pp 419-424 October 1988
Effect of gibberellic acid was studied on nitrate utilization inSesamum seedlings grown under continuous light in standard mineral medium. Gibberellic acid treatment markedly inhibited nitrate uptake and its reduction. Sucrose 2% (w/v), when added in the incubation medium, significantly reversed this inhibition. Further, sugars and chlorophyll contents were also low and Hill-reaction activity recorded inhibition in GA3 treated seedlings. The poor uptake and reduction of nitrate is a result of low level of tissue sugars in gibberellic acid treated seedlings.