Effect of Aqueous Extract of some Windbreak Tree Leaves on Seed Germina-tion and Seedling Growth of Squash

Abstract

The effects of aqueous leaves extract of three types of windbreak trees, Acacia, Casuarina, and Eucalyptus, were tested at 0, 25, 50, 75, and 100 g.L-1 for their effect on squash (Cucurbita pepo L.) seed germination and seedling growth. A group of squash seeds was sown in pots and irrigated with aqueous extract concentrations until the germination stage, while another group of seeds was maintained for three weeks under the same treatments until the seedling stage. Treating seeds with aqueous extract of Acacia resulted in a significant decrease in the percentage of germination (GP) and the germination rate (GR) of the seeds. The aqueous extract of Eucalyptus also led to a slight decrease in the GR, while no effect was observed when the aqueous extract of Casuarina was used. Treatment of seedling, on the other hand, with an aqueous extract of all windbreak types decreased all of the seedling growth parameters, fresh and dry weight (FW and DW), water content (WC), length of petioles (LP), number of buds (NB) and number of leaves (NL). The three windbreak trees induced an allelopathic effect on squash seedling growth in particular, more than the squash seed germination, but at different degrees. Acacia extract resulted in the highest effect, while Eucalyptus and Casurina resulted in intermediate and low inhibitory effects respectively. In all three windbreaks, the inhibitory effect of the extract on the seed germination and seedling growth increased as the extract concentration increased from 0 to 100 g.L-1.