Volume 89, Issue 6
December 1980, pages 429-528
pp 429-435 December 1980
Pollen-carriers of 5 taxa of periplocaceaesensu stricto are described. These are ill organised inCryptolepis andCryptostegia and well organised inDecalepis andHemidesmus. The pollen tetrads are free in the former two taxa but organised into massulae in the latter. In their pollen carriersDecalepis andHemidesmus appear to connect periplocaceae with Secamonoideae of Asclepiadaceae.
pp 437-442 December 1980
In all the three species studied stomata are mostly confined to the upper epidermis but a few occur on the lower surface as well. Development is of the perigenous type. The reduction in number of cell divisions in and around the stomata in parasitic and aquatic plants is discussed.
pp 443-456 December 1980
The wood anatomy of 17 species representing 14 genera has been investigated. The wood is diffuse porous. It is composed of vessels, tracheids, fibres, axial parenchyma and rays. The vessels are either scattered solitary or in radial or tangential multiples of two or three or in long radial chains. All the lianas and a few trees studied have two types of vessels with narrow and broad diameter. The vessels usually show a simple perforation plate. Two main types of xylem fibres, the fibre tracheids and the libriform fibres intergrade with each other. The xylem parenchyma is paratracheal, vasicentric and confluent to aliform. The rays are uni- or multiseriate, homogeneous or heterogeneous and their length varies in different species.
pp 457-464 December 1980
The effect of kinetin and morphactin on flower sex expression has been studied in castor. It was observed that the ratio of female to male flowers was 1:4·75 in control; 1:1·61 in kinetin and 1:3·29 in morphactin treated plants. Although the number of female flowers increased in morphactin-treated plants, the sex ratio did not alter much as there was slight decrease in male flowers. Kinetin elicited an increase in femaleness and decrease in maleness, consequently causing reduction in total number of flowers, compared to control plants. Carbohydrate contents were increased with kinetin and morphactin treatments. Reducing and non-reducing sugars were more in the female flowers than male flowers. Male flowers surpassed female flowers with respect to starch content. Treatments increased total protein and soluble nitrogen in the shoot tips, compared to those of control plants. Total and soluble nitrogen were low whereas protein nitrogen was higher in the pistillate flowers than in the staminate flowers. The modification of sex expression is discussed with respect to carbohydrate and nitrogen metabolism.
pp 465-472 December 1980
Two morphologically similar species ofChlorophytum (Liliaceae), namely,C. glaucum Dalz. andC. glaucoides Blatt, occur in hilly ranges of the Sahyadris in Western India. Although it is difficult to distinguish them in natural habitats their closer examination reveals a number of well-defined morphological differences. Both grow intermixed in certain parts of their distributional range and interbreed occasionally giving rise to a few individuals that are intermediate in appearence. Their careful examination revealed abnormal meiotic behaviour in their PMC’s leading to high percentage of sterility.
The ability of these sympatric species to intercross suggests that their genomes are not greatly dissimilar and hybrid sterility may be interpreted as a post-zygotic isolating mechanism. Most probablyC. glaucum, normally inhabiting higher altitudes and more wet situations has been differentiated fromC. glaucoides occupying lower elevations with relatively drier climatic conditions, by way of ecotypic differentiation and chromosomal rearrangement.
pp 473-479 December 1980
Algae isolated and identified asCephaleuros were studied under laboratory condition for their morphological characteristics. These were analysed numerically along with the describedCephaleuros species. The taxonomic trends exhibited by the different species and the behaviour of the cultures are discussed.
pp 481-484 December 1980
Salt tolerance capacities of some ragi cultivars were studied at different levels of salinity during early seedling growth. The cultivars Kalyani and EC-955 showed high percentage of germination, greater survival of seedlings, high levels of proline in higher salt solution and thus show a high degree of tolerance when compared to other cultivars. The relevance of these changes in relation to varietal adaptability to salinity has been discussed.
pp 485-489 December 1980
Studies on the prevalence of the root nematodeHirschmanniella mucronata in rice and rice soils revealed four distinct peaks of population, viz., last week of September, first week of November, third week of December and second week of February. The nematode was active particularly in the presence of standing crops. Positive correlations exist between the fresh weight of roots and soil temperature at 5 cm depth, with the development of gravid females and the build-up of the nematode.
pp 491-496 December 1980
Histopathological aspects of orange and guava are studied. The rotten orange pericarp shows distorted epidermis. The outer pericarp cell layers show spores of pathogenic fungi. The general cellular organisation is disturbed. Oil ducts get collapsed and the lignin deposits on the walls of tracheids are degenerated. In guava, small and large cavities are formed in the outer pericarp. The most interesting feature was the presence of very thick-walled sclereids in the pulp of rotten guava.
pp 497-503 December 1980
Inheritance of eight morphological characters, namely, prostrate growth habit; narrow, bicompound and simple leaves; purple and light green foliage colours; light blue corolla and green seed coat colour, was studied. AU the traits except the light blue corolla showed monofactorial recessive inheritance, while the light blue corolla involved interaction of two recessive factors. Joint segregations of narrow leaf and double-flowered peduncle and simple leaf and light blue corolla were studied, and in both cases no linkage was detected.
pp 505-518 December 1980
Seasonal fluctuations of the fauna associated with the water fern,Salvinia molesta growing in a lotic habitat and the fluctuations during the three stages of the fern’s growth in a lentic habitat were studied. As many as 66 species belonging to six phyla were recorded, the major components being crustaceans, insect larvae and gastropods. The density of the fauna of the lotic habitat varied between 1267–7663/kg ofSalvinia, and thatof Salvinia of floating stage, intermediate stage and grown up stage (overcrowded) of the lentic habitat were 9610, 8860, 108 respectively/kg. Prolonged overcrowding ofSalvinia resulted in a sharp decline of the associated fauna.
pp 519-528 December 1980
Salvinia molesta Mitchell propagates vegetatively by proliferation. Spores are nonviable. Mechanical disturbance enhances the rate of proliferation. The rates of proliferation within 30 days are 1: 8 in agitated media and 1: 1 · 6 in intact media under laboratory conditions. While the frequency of addition of fresh set of leaves ranged between 3–18 days in the natural habitat it was between 3–9 days under the laboratory condition. Crowding ofSalvinia is a prerequisite for the cessation of proliferation and initiation of the final ‘grown up stage’.Salvinia of ‘floating stage’, ‘intermediate stage’ and ‘grown up stage’ have different density ranges such as 765–986, 942–1280, and 65–345/m2 and biomass ranges of 18–25, 50–70 and 340–375 g dry wt./m2 respectively under natural conditions.