Measurements of nucleic acid relatedness provide a genetic means for under-standing the relationships of species and higher orders of classification among the fungi. Nuclear DNA reassociation effectively separates species but resolves no further than to the sibling species level. Approximately this same level of resolution results from comparisons of mitochondrial DNA fragments generated with restriction endonucleases. Comparisons of ribosomal RNA divergence measured from either hybridization or sequencing give a means for assessing more distant relationships.

Morphogenetic changes involved in the gall leaves ofMimusops elengi Linn. (Sapotaceae) as a result of deliberate changes in the feeding sites ofArrhenothrips ramakrishnae Hood (Thysanoptera: Insecta) have been investigated. A comparative histochemical study of the normal as well as gall tissues revealed a higher incidence of protein, lipids, starch, tannins as well as enzymes such as acid phosphatase, peroxidase and polyphenol oxidase in gall tissues. Turgid hypertrophied cells in the gall mesophyll and their functional relationship with peroxidase evoke interest particularly in the context of the morphogenetic behaviour of gall-laminar under different experimental verifications, essentially because the causal relationship between the treatment with peroxidase and curling of root slices are known.

In the primary leaves of mungbean (Vigna radiata (L.) Wilczek) seedlings, grown in pots containing soil, changes in the contents of chlorophyll, soluble protein and reduced nitrogen were related to changes in the activities of aminopeptidase, carboxypeptidase and endopeptidases (assayed with casein as substrate at pH 5·0 and 7·3), Chlorophyll degradation commenced subsequent to protein breakdown. The decrease in soluble protein and leaf N content during senescence was not accompanied by a corresponding increase in free amino acid level. Aminopeptidase and carboxypeptidase activities were high in the young primary leaves. In senescing leaves, undergoing rapid loss of nitrogen, the aminopeptidase activity remained low while carboxypeptidase activity declined significantly. The endopeptidase activity at pH 5·0, however, increased more than 3 fold during this period. At pH 7·3, the activity was low.

Effect of single superphosphate, urea, ammonium sulphate, potassium sulphate and animal dung on the formation of sporocarps inAzolla pinnata under the field conditions is studied. Of the 4 strains (India, Thailand, Vietnam and Bangladesh), the Bangladesh strain produced maximum number of sporocarps (mega+micro); the Vietnam strain developed maximum number of microsporocarps, but no megasporocarps. Animal dung at 1·0 t/ha enhances sporocarp formation. Phosphorus deficiency enhances formation of megasporocarps, while superphosphate decreases their number. Ammonium sulphate or urea at 30 kg N/ha increases the number of microsporocarps, while potassium sulphate increases their number irrespective of the rate of application.

Field and laboratory experiments conducted using 8 isolates ofAzolla pinnata from India and one each from Thailand and Vietnam showed differential behaviour in their growth and nitrogenase activity. Under field conditions, an isolate from Sambalpur (Orissa state) showed better nitrogenase activity, whereas vegetative growth was more in Thailand and Vietnam isolates. In the laboratory, Thailand isolate recorded maximum nitrogenase activity; Thailand, Varanasi II and Vietnam isolates had similar vegetative growth.

The effect of various pH (5·5, 6·5, 7·5 and 8·5) and temperature (20, 25 and 30°C) on germination of spores ofGlomus fasciculatum on 1% water agar was studied. Maximum germination (81·3%) occurred at pH 6·5 at 25°C. Spore germination was also studied with other nutrient media such as corn meal agar, modified Hepper medium, charcoal agar (0·01%) and soil extract agar. A significant increase was observed in charcoal agar and soil extract agar (+13·4% and +10·9% respectively).

The different dimensional aspects of petiolar anatomy of 35 taxa of Verbenaceae has been traced with a view to reveal the structural diversity and to evaluate the contribution of petiolar anatomy to the taxonomy of Verbenaceae. Seven parameters were quantitatively analysed for the patterns of variability. The different vascular configurations in various taxa were found to be taxon specific and hence can be utilized as a taxonomic marker. The observation of internal phloem in the petiole ofAvicennia andTectona is an additional information relevant to the anatomy of Verbenaceae. The variation patterns in the petiolar anatomy of different taxa were found to have some adaptive significance.

Extracellular xylanase of 5 isolates of thermophilicSporotrichum sp. andMyceliophthora thermophilum was studied in media containing wheat straw, wheat bran, paddy straw, paddy husk, sugar cane bagasse and local grass (Cyanodon dactylon L). Maximum D-xylanase (0·92 IU/ml) was secreted on 6th day bySporotrichum sp. strain 1 in a basal medium that contained 5% (w/v) wheat straw; treatment of straw by 4% NaOH prior to fungal fermentation did not alter xylanase yields appreciably. Temperature and pH optima for enzyme production were 45°C and 5·0 respectively. Enzyme activity showed a temperature optima of 70°C, pH maxima of 5·5 and a substrate level of 3% larch wood xylan. Xylanase ofSporotrichum sp. strain 1 was inducible and highly thermostable; nearly 70% of activity was retained even after 5 min exposure at 80°C. Associated cellulolytic activity (0·12 IU/ml) was detected in the crude enzyme preparation.

The structure and development of the bulbils ofChara hornemannii, Chara aspera, Lamprothamnium papulosum, Lamprothamnium succinctum andNitellopsis obtusa have been studied.

The present study was conducted around the Almora town involving 12 forest sites on south, north and west slopes along an altitudinal gradient of 1600–2000 m.Pinus roxburghii Sarg. was the dominant species at lower altitude andQuercus leucotrichophora A. Camus. at higher altitude. Except for the dominant species, most of the species are contagiously distributed. Data of community coefficients indicate that the forests of lower elevations are most dissimilar compared to those at higher elevation. However, the community of same elevations are most similar to each other. Regeneration status was good in the experimental forest sites. However, regeneration ofQuercus leucotrichophora was better on the north and west aspects and ofPinus roxburghii on south aspect.