K.P. Sharma

Seed germination and occurrence of seedlings of Typha species in nature

Abstract This paper reports for the first time the occurrence of Typha seedlings within natural stands of Typha . The species investigated, Typha angustata Bory and Chaub. and T. elephantina Roxb., do not have any autotoxic effect on seed germination.

Allelopathic influence of algae on the growth of Eichhornia crassipes (Mart.) Solms

Abstract The growth of Eichhornia crassipes (Mart.) Solms was inhibited when grown in water containing algae such as Scenedesmus bijugatis (Turp.) Kuetz, Chlorella pyrenoidosa Chick and species of Aphanothece, Euglena, Merismopedia and Coelastrum. The size of plants, their dry weight and chlorophyll a and b contents and their rate of vegetative propagation were very much reduced compared with control plants grown in algae-free water. The hyacinth plants ultimately died after 90–100 days of growth with algae.

Seasonal changes in concentration of major nutrient elements in the rhizomes and leaves of typha elephantina roxb

Abstract The tissue concentrations of calcium, magnesium, nitrogen and phosphorus in the leaves (aboveground shoots) and vertical branches of rhizomes of Typha elephantina Roxb. were studied near Jaipur (India) during 1975–1976. The calcium and magnesium concentrations did not show clear trends of seasonal change. Nitrogen exhibited two peak levels in the leaves during May and November, and a peak in the rhizomes during March. Phosphorus concentration exhibited two peak levels in the rhizomes during July and January, and at least one clear peak in the leaves during April. Total nutrient contents were calculated using biomass data for leaves published earlier. It is estimated that about 35% N and 50% P of the total maximum content in the leaves translocated to the rhizomes during winter and later some of it was used again for new shoot growth. The significance of the changes is briefly discussed.

Light regulated seed germination in Typha angustata Bory et Chaub

Abstract The seeds of Typha angustata Bory et Chaub. germinate at room temperature (25–27°C) only in the presence of light. Percentage germination increases with an increase in both light intensity and duration. 100% germination occurs within 48 h at 1000 lux and 18 h photoperiod. Germination is inhibited by blue light, but this can be reversed by exposure to yellow or red light. The longer the exposure to blue light, the longer is the duration of yellow or red light required to overcome the inhibition. The significance of these findings is briefly discussed.

A note on the identity of Typha elephantina roxb.

A comparative account of the morphology of Typha elephantina Roxb. and Typha angustata Bory et Chaub. is presented to show that T. elephantina is a distinct species, distinguished from other species of the genus by its robust habit, elaborate rhizome system and stiff trigonal leaves.

Temperature-regulated seed germination in Neptunia oleracea Lour. and its ecological significance

Abstract Germination of seeds of Neptunia oleracea Lour. was 100% after two cycles of alternately high and low temperature (60°C for 8 h and 20°C for 16 h, respectively) in submerged conditions. Only 77.5% germination was recorded in moist conditions following dry storage of seeds at 80°C for six days. Alternating temperatures, comparable to those in the experimental treatments, appertain in the Ghana Bird Sanctuary, Bharatpur (India), an area in which N. oleracea is abundant.

Studies of wetlands in India with emphasis on structure, primary production and management

Abstract This paper briefly reviews the Indian studies on community structure, standing crops and primary production in inland freshwater wetlands. The problem and the state of wetland management in India has also been briefly discussed.

Effect of cutting of aboveground organs of Typha angustata Bory & chaub on its growth and total chlorophyll content

Abstract After a seven-month period of establishment in concrete tanks, the further growth of plants of Typha angustata Bory & Chaub was markedly decreased by three successive cuttings of shoots 5 cm above water level. Compared with control plants, the percentage reductions were: aboveground biomass, 97%; belowground biomass, 75%; shoot densities, 45–55%; chlorophyll content 77%. After these cuts at two-weekly or monthly intervals, the plants were still viable and ultimately able to regenerate.

Ecology of plant populations I: Growth

Populations are basic functional units of an ecosystem and therefore, a knowledge of their ecological equipment is essential to the understanding of both the ecosystem and the role of these populations in it. Ecology of a population is concerned with the distribution and abundance of the particular species and its temporal changes in relation to resource requirement, environmental influences and the interactions between individuals in different populations (Begon et al. 1986). Thus, an understanding of the ecology of different species populations is also a prerequisite to their management, which is essentially concerned with regulating their size (through control, utilisation or otherwise) to the advantage of human beings.