Influence of tillage methods and vine killing on some physical properties and surface hardness of potato tuber

A‎ field study was conducted to compare the effects of four primary tillage implements (moldboard (MB), disk (DP), improved disk (IDP) and chisel (CH) ‎plows) and two vine killing methods (vine killed (VK) and without vine killing (NVK)) on some physical and hardness properties of potato tuber. The study was conducted using a 4‎‏×‏‎2 factorial experiment (strip plots) ‎with a randomized complete block design. Eight ‎treatments representing four primary tillage implement levels and two levels of ‎vine killing were replicated three ‎times. The results showed that tuber dry matter content in "MB.NVK" and "DP.NVK" treatment was significantly higher than that of "IDP.VK" at 5%‏ level. The multiple linear regression analysis with stepwise method showed that there was a linear regression model between tuber dry matter content and wet weight, moisture content, maximum diameter and spherisity.