Two field experiments were carried out during the summer seasons of
2000 and 2001. The objective of this study was to investigate the effects of
soil water matric potential (SWMP) treatments (-35, -45, -55, -65 and -75 J.kg-
1) on vegetative growth, yield and quality of the two potato cultivars Diamant
and Dra~a. The obtained results of the two seasons showed that irrigation at -
55 J.kg- was superior and significantly increased plant height, leaf area,
foliage fresh and dry weights, average tuber weight and tuber yield, compared
with the other four SWMP treatments. Results showed also that the lowest
SWMP (-75 J.kg-¹) decreased the previous mentioned parameters more than
the highest one (-35 J.kg-\ Dry matter, starch and specific gravity of tubers
increased significantly as the SWMP treatments decreased, while total sugars
decreased by increasing SWMP. There were some insignificant differences on
nitrogen, phosphorus and potassium contents due to SWMP treatments. The
cultivar Diamant showed higher mean values of plant height, leaf area, foliage
fresh and dry weights, average tuber weight and total tuber yield, compared
with Draga cultivar. Tubers' quality;in terms of dry matter, starch, total sugars
and nitrogen contents; appeared significantly better for Diamant than Draga.
The greatest response in terms of vegetative growth, yield and quality of
potato were obtained when Diamant cultivar was irrigated at -55 J.kg·¹ SWMP