Effect of soil and water characteristics on yield and properties of 'Spunta' potatoes

Soil texture and its characteristics besides water characteristics can play an eminent role in potato (Solanum tuberosum L.) production. Therefore, a soil and water quality index (SWQI, %) was derived to investigate the effect of combination of soil and water characteristics (sodium adsorption ratio for water and soil, electric conductivity of water and soil, pH for water and soil, organic matter in the soil, and soil texture index) on yield and properties of 'Spunta' potatoes produced under center pivot irrigation system. This index was formed studying separately the effect of irrigation water quality and soil texture on yield, water use efficiency, tuber modulus of elasticity, and tuber shape index of 'Spunta' potatoes. Field results demonstrated that the lowest potato yield was approximately 34.12 t ha(-1) at SWQI 79.63%, and the highest potato yield was 37.79 t ha(-1) at SWQI of 30.93%. The lowest water use efficiency was approximately 6.09 kg m(-3) at SWQI 30.93%, and the highest water use efficiency was 6.83 kg m(-3) at SWQI 79.63%. The lowest tuber modulus of elasticity was approximately 3.98 N mm(-1) at SWQI 21.7%, and the highest tuber modulus of elasticity was 4.74 N mm(-1) at SWQI 79.63%. Finally, the tuber shape index was approximately 342% at SWQI 79.63%, 418% at SWQI 21.72%, and 403% at SWQI 30.93%, which belongs to long and very long shapes. The soil and water quality index could be a useful tool to get relationships among water and soil characteristics, yield, and other properties of the potato crop.