EFFECT OF ORGANIC FERTILIZER IN COMBINATION WITH SOME SAFETY COMPOUNDS ON GROWTH AND PRODUCTIVITY OF POTATO PLANTS GROWN IN WINTER SEASON

Two field experiments were carried out during the two successive winter seasons of 2013/2014and 2014/2015 in a private sector farm at Kafr Elsohbi Village, Qalubia Governorate, Egypt to investigate the effect of different levels of organic fertilizer (compost) at 35.7, 47.6 and 59.5 ton/ha. in presence of mineral and bio fertilizers and foliar spray with salicylic acid (SA) at 200 ppm, putrescine at 200 ppm,  monopotassium phosphate at 2g/l and ascorbic acid at 200 ppm as well as their combinations on vegetative growth characters, chemical constituents, total yield and quality of potato (Solanum tuberosum L.) cv. Lady Rosetta during winter season.  Obtained results showed that, fertilizing potato plants with compost at different used rates significantly increased all measured vegetative growth traits, chemical constituents of plant foliage, total produced tuber yield and its components, large and medium size tubers as well as chemical constituents of produced tubers. However, it decreased nitrate and total sugars percentage of produced tubers. Moreover, using the highest compost rate (59.5ton/ha.) exhibited the highest values in all aforementioned traits. Also, spraying potato plants four times starting one month from planting and every two weeks by interval with putrescine at 200 ppm and monopotassium phosphate at 2g/l reflected the highest values of vegetative growth aspects and chemical constituents of plant foliage as well as total produced tuber yield and its quality without significant differences among them compared with other tested growth stimulants and the control. In this respect, fertilizing potato plants grown under sandy loam conditions with compost at 59.5 ton/ha. combined with spraying the plants four times with either monopotassium phosphate at 2g/l or putrescine at 200ppm exhibited the highest values of total produced tuber yield and its components with best quality.