RESPONSE OF PROPOLIS EXTRACT­ PRESOAKING SEEDS OF SOME CROPS TO SALT TOLERANCE UNDER DIFFERENT SOIL CONDITIONS

Abstract

This investigation was conducted during the seasons of 1999/2000 and 2000/200 I at the Experimental Area of Faculty of Agriculture, Fayoum, Cairo University, to study the effect of propolis extract seed/grain presoaking on germination and chemical composition of treated seeds/grains (in a laboratory study) of sugarbeet (cv. Nour), wheat (cv. Sakha 8), maize (cv. Trihybrid 310) and sorghum (cv. Giza 15) as well as emergence, growth, yield and its components and chemical composition of different parts (roots, stems and leaves) of the above mentioned crops sowing in clay and calcareous soils (in a pot stucjy). Propolis used in this study was prepared to obtain propolis extract (PE) at the concentration of 5% which used either non-salinized or salinized with NaCI salt till the concentration of 3000 ppm for soaking seeds/grains before sowing for 6 or 12 hrs. Treatments comprised nine classes for the laboratory study and seven classes for the pot study. In the pot study, vegetative growth parameters of previously mentioned crops were recorded at different sampling times (30, 60 and 90 days after sowing for sugarbeet and wheat, while 25, 50 and 75 days after sowing for maize and sorghum). The obtained results are tabulated as a mean of the two successive seasons and could be summarized as follows: Regarding laboratory study, seed/grain gem1ination%, germination rate index, the concentrations of total sugars, free proline, total free amino acids, total soluble phenols, gibberellins, indole acetic acid and nucleic acids (DNA, RNA and total nucleic acids) as well as the activity of a-amylase were significantly increased with seeds/grains under different applied treatments as compared to untreated seeds/grains. The highest values of all previous mentioned paran1eters were recorded with soaking seeds/grains in propolis extract. Concerning pot trial, emergence%, growth parameters and yield and its components of all crops under study as well as the concentrations of indoles in stems and leaves, nucleic acids (DNA, RNA and total nucleic acids) in different plant parts and leaf pigments (Chi. a, Chi. b and total carotenoids) and the activity of leaf a-amylase were significantly increased while, the concentrations of total sugars, free proline and total free amino acids of different plant parts and roots indoles as well were recorded the contrary with clay soil as compared to calcareous soil. All previous mentioned parameters scored the highest values with soaking seeds/grains in propolis extract, with some exceptions, as well as with combination between soaking seeds/grains in propolis extract and clay soil irrigated with tap water, with some exceptions, with considering that combination between soaking seeds/grains in propolis extract or NaCl-salinized propolis extract and calcareous soil exhibited good results. Finally, in view of the obtained results, seed/grain genninability, growth and yield and its components as well as chemical composition of plants could be notably improved under saline conditions by the appropriate propolis extract seed/grain presoaking for suitable periods proportional to every crop seeds/grains.