EFFECT OF DIFFERENT LEVELS OF SALINITY ON SEED GERMINATION OF FOUR SELECTED TREE SPECIES

Salinity is one of the most adverse factors, which restrict the economic utilization of availableland resources in the dry zone of Sri Lanka. The salt affected area in Sri Lanka is estimatedabout 223,000 ha, which comprises 3% of the land area of the Island, found mainly in the dryzone (Vivekanandan, 1989). The most of the salt affected lands are generally barren, with littlewoody vegetation of salt tolerant bushes and herbaceous flora. This resulted in serious soilerosion and land degradation problems, which spreads into adjoining productive agriculturallands too. Therefore it is very important to restore these lands for useful agricultural purposes. Inthis context, the present study was mainly focused to determine the effect of salinity on seedgermination of four selected tree species, namely Castor (Ricinus communis), Ipil-ipil (Leucenealeucocephala), Wood apple (Feronia limonia) and Kottamba (Terminalia catappa) in order tostudy the possibility to regenerate these tree species by direct seeding in salt affected lands.Four separate pot experiments were conducted by using above four tree species in sand trays. Allexperiments were arranged in a Complete Randomized Design with 5 replicates. 100 seeds wereplanted in each tray for germination. Trays were kept moist with different levels of saline water(i.e. 0.13 (normal water) 4, 8, 12, 16, 24, 32, and 40 (Seawater) mmhos/cm) by diluting seawateras assigned in different treatments throughout the experimental period.Result revealed that seed germination in control treatments was higher in Wood apple (100%)and Castor (72%) than Kottamba (31%) and Ipil-ipil (13%). Seed germination was decreasedwith increasing level of saline level in Kottamba and Castor. In Kottamba, no germination wasobserved at all when at salinity level increased up tc 16 mmhos/cm while in Castor germinationwas nil when salinity level increased up to 40mmhos/cm. In Wood apple, more than 80% ofgermination was recorded even up to the salinity level of 24 mmhos/cm. Germination was poorin Ipil-ipil even in control treatment and not significantly decreased up to the salinity level of 40mmhos/cmTherefore, the species can be ranked in order to tolerance to salinity in terms of germination asfollows: Ipil-ipil>Wood apple>Castor>Kottamba.

A preliminary study on the effects of gliricidia leaf extract on growth performances of tomato (Lycopersicon esculentum)

The suitability of gliricidia (Gliricidia sepium) leaf extract to replace 100%, 75 %, 50 % and 25 % of Albert solution in growth of tomato (var. Thilina) was tested. The research was conducted under the protected plant house conditions at Faculty of Agriculture, University of Ruhuna. Polybags filled with the medium of 1:1 coir dust and sand and the solutions prepared by mixing different composition of gliricidia leaf extract and Albert solution were used for the experiment. 100 g ground gliricidia leaves were mixed in 1 L of water and filtered to prepare nutrient solutions. Growth performances of plants were recorded 12 weeks post treatments. Significantly (P<0.05) lower plant height was observed in plants treated only with gliricidia leaf extract whereas, significantly higher leaf number was observed in plants treated only with Albert solution (control). Performance of plant growth in respect to time taken for flowering also showed significant differences among treatments where, plants in control took shortest time but the time gap was only 6 days. Plants treated with 25% gliricidia extract and 75% Albert solution showed significantly higher yield. According to these results it could be concluded that the growth performances of tomato are reduced with increasing level of gliricidia leaf extract but with considering the yield gliricidia leaf extract could replace about 25% of Albert solution giving an additional benefits to reduce cost of production