ROLE OF BIO AND ORGANIC FERTILIZERS IN REDUCING SOME CHEMICAL FERTILIZERS DOSES ON YIELD OF STEVIA PLANTS UNDER SOME DIFFERENT SOIL TYPES

Abstract

To study the influence of organic and bio fertilization compared with NPK fertilization and their interactions on yield of stevia plant (Stevia rebaudiana Bertoni) under some different Egyptian Soils Conditions was carried out a pot experiment at the Experimental Farm of the Fac. Agric. Mansoura Univ. during the summer season of 2013. The experimental design of present study was complete randomized block design with three replications, where soil types represent blocks and each block contains fertilization treatments. Three soil types were used as clay, saline and calcareous and six fertilization treatments are contained in each soil type as control, 100 % of recommended NPK fertilizers,50 % of recommended NPK fertilizers, biofertilizer, organic fertilizer (compost), and mixture of 50 % of recommended NPK + bio + compost. Results indicated that application all fertilizer sources increased the means values of leaves, stems and shoot fresh weights (32.3, 39.7 and 72.0 g/pot) and the others treatments of fertilizers used (63.6, 60.4, 48.6 and 38.9 g/pot for the treatments of mixture, 50 %, organic and biofertilizer, respectively). The corresponding values of increases over control due to the aforementioned respective treatments were 42.5, 34.1, 30.9, 19.1 and 9.0 g/pot. These increases represent the following percentages over control : 144.6, 115.6, 104.7, 64.7 and 30.5 %, respectively. Also dry yield was (24.1, 23.1 and 47.2 g/pot) of stevia plants significantly than control (without fertilization). Concerning to soil types revealed that the greatest value was obtained due to growing stevia plants on clay soil compared to both saline and calcareous soils. The greatest shoots plant fresh weight of stevia was obtained due to growing in clay soil where the mean value was 64.3 g/pot. Both saline and calcareous soils were followed clay soil where the respective mean values of shoot plant fresh weight were 48.5 and 43.8 g/pot. While The highest shoot plant dry yield of stevia was obtained due to growing stevia plants on clay soil where the mean value was 43.2 g/pot. Both saline and calcareous soils were followed clay soil where the respective mean values of shoot plant fresh weight were 31.4 and 28.0 g/pot. In addition, all fertilizers treatments eliminated bad effect of both saline and calcareous soils in comparison with control (interaction effect).