PJB-1993-21
COMPETITIVE INTERFERENCE BY SOME INVADER SPECIES AGAINST KALLAR GRASS (LEPTOCHLOA FUSCA) UNDER DIFFERENT SALINITY AND WATERING REGIMES
KHALID MAHMOOD, KAUSER A. MALIK, M.A.K. LODHI* AND KHALID HAMID SHEIKH
Abstract
Kallar grass [Leptochloa fusca (L.) Kunth] was grown in mono-cultures and in mixed-cultures with Suaeda fruticosa (L.) Forssk., Cynlodon doctylon (L.) Pers., and Sporobolus arabicus Boiss., under different soil salinity and water conditions. The biomass yield data indicated that Kallar grass is a weak competitor against S. fruticosa at high salinity and against C. doctylon at low salinity, while its growth was not affected due to competition by S. arabicus. However, the yield of Kallar grass in mono-cultures (2 plants/pot) was significantly higher than that in corresponding mixed-cultures (2 plants Kallar grass + 2 plants of weed/pot). Although Kallar grass growth was low in its mono-cultures with 4 plants/pot compared to 2 plants/pot, it suffered more severe' interference from weed species under certain conditions than from its own individuals. In general, at a particular salinity and watering treatment, nutrient concentrations in plant shoots of a species grown in mono- and mixed-cultures were similar. However, total uptake of nutrients (N,P,K,Ca and Na) by Kallar grass and competing species differed significantly and weed species removed proportionately higher amounts of nutrients in mixed-cultures. The significance of competitive interactions among species with regard to their coexistence and productivity in a common environment in saline areas is discussed.
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