Volume 100, Issue 5
October 1990, pages 1-359
pp 1- October 1990
pp 279-283 October 1990
A new genusUnguiculariella under the family Hyaloscyphaceae, order Helotiales of the inoperculate Discomycetes is proposed for material collected from Bhutan. The species,Unguiculariella bhutanica Thind and R Sharma gen. et. sp. nov., is described and illustrated.
pp 285-299 October 1990
A revision of the genusDimorphocalyx Thw. (Euphorbiaceae) for India and adjoining countries is presented. Three species and two varieties are recognised.Dimorphocalyx beddomei (Benth.) Airy Shaw is endemic to south India.Dimorphocalyx lawianus Hook. f., endemic to south India is reduced to a variety ofDimorphocalyx glabellus Thw.Dimorphocalyx dilipianus Balakr. and T Chakrab. is reduced to a synonym ofDimorphocalyx balakrishnanii T Chakrab. and Premanath, endemic to Andaman Islands. Keys to the taxa, taxonomic descriptions and illustrations are presented.
pp 301-309 October 1990
Structure and development of seed coat inSesbania speciosa were observed by light and scanning electron microscopy. Only the outer integument forms the seed coat. The inner integument disintegrates during seed development. The epidermis of outer integument differentiates into the macrosclereid layer and the hypodermis into the osteosclereid layer. The tracheid-bar is present below the well defined and complex hilar region. The seed coat surface shows deposition of cutin in the form of rope-like upwellings which make it impermeable to water. The macrosclereid cells are packed very tightly and this compactness may also be responsible for the impermeability.
pp 311-318 October 1990
Cowpea (Vigna sinensis L.) cv. Rituraj was grown in refined sand at graded levels of boron ranging from 0·0033 to 6·6 mg l−1. Maximum biomass and seed weight were obtained at 0·33 mg B l−1 supply. In acute deficiency of boron (0·0033 and 0·033 mg l−1), its deficiency symptoms were pronounced, the biomass was depressed markedly and neither pods nor seeds were formed. At moderate deficiency of boron, deficiency symptoms were mild and the number and weight of seeds were reduced by about 40% and 50% respectively. Marked boron toxicity symptoms were observed at 6·6 mg B l−1 supply where not only biomass and seed yield but also the concentration of starch and non-reducing sugars and the activity of starch phosphorylase and ribonuclease were depressed. In the latter treatment reducing sugars were increased so also the activity of polyphenol oxidase and peroxidase. In acute boron deficiency, the concentration of reducing sugars and non-reducing sugars were increased so also the activity of peroxidase, ribonuclease and polyphenol oxidase but the activity of starch phosphorylase was depressed only at 0·0033 mg B l−1 supply. As the concentration of boron in seeds was markedly less than in leaves, the values of deficiency, threshold of deficiency and threshold of toxicity in leaves was higher than in seeds.
pp 319-331 October 1990
Cytological exploration of 47 woody leguminous species have been made from the forests of northern, central and southern India. Of these,Acacia canescens (n=13),Dichrostachys cinerea (n=26),Erythrina caffra (n=21),Millettia brandisiana (n=11),Mucuna hirsuta (n=11),Pahudia martabanica (n=12) andPhanera glauca (n=14) are explored for the first time. Additional and/or variable cytotypes are recorded inBauhinia acuminata (n=13) andProsopis glandulosa (n=28). Existence of B-chromosomes has been recorded inErythrina caffra (n=21+0−3B),Millettia brandisiana (n=11+0−2B),Pongamia pinnata (n=11+0−7B) andTamarindus indica (n=13+0−4B). Besides these cytomorphological variabilities, structural heterozygosity for translocations/inversions (Ougeinia oojeinensis, Pongamia pinnata, Saraca indica) and cytomixis (Caragana brevispina) are also existent.
pp 333-336 October 1990
The distribution, collection, morphology and cytology ofSorghum nitidum (Vah1) Pers. belonging to the sectionParasorghum of genusSorghum are presented. The species collected in the western ghats of Tamil Nadu and Kerala has 10 normal (A) chromosomes (2n=10) and 3 supernumerary (B) chromosomes, which are reported for the first time in Indian collections.
pp 337-342 October 1990
The evolutionary shifts in the seed packing features of the plants during domestication were studied by comparing a set of domesticated legumes with the wild species. The domestication considerably reduced the packing cost of the seeds in terms of pod coat weight per unit weight of seeds. This reduction is a result of increased seed weight per pod and the average seed weight, probably at the cost of seed number per pod, while the podcoat weight per pod was maintained during domestication. Eventhough, the average seed weight increased by 8-fold from wild to domesticates, the increase in pod coat weight per seed was only 2-3-fold. It is possible to separate wild and domesticates into distinct clusters on the basis of their individual seed weight and packing costs. We discuss the evolutionary implications of these results.
pp 343-352 October 1990
Several strains ofCandida tropicalis isolated from the dung of buffalo, cow and goat have been found to fix N2. The nitrogenase activity (acetylene reduction) varied between 73 and 1162 nmol (mg protein)−1 h−1. 2·2–9·3 mg N2 were fixed g−1 glucose consumed. Acetylene was reduced progressively with time. Acetylene reduction could not be observed in cells treated with cycloheximide but was unaffected by antibiotics which inhibit the growth of prokaryotes.
pp 353-359 October 1990
Nitrogenase activity of 4 strains ofCandida tropicalis exhibited a pH optimum of 7·2 and an optimum temperature of 30°C; it was depressed by NH4+ ions and at 1 mM no activity could be detected. 2,4-Dinitrophenol, sodium azide andp-chlormercuribenzoate abolished nitrogenase activity completely at 2·5×10−4 M. Nitrogenase activity was increasingly inhibited by O2 with increasing concentrations; it was also inhibited by methane and methanol. The yeast cells possessed active uptake hydrogenase activity.