the effect of planting pattern and water levels on the yield of potatoes under drip irrigation

to study the effect of planting pattern and water quantity on potato yields under drip irrigation, this research was conducted using a split plot based on a randomized complete block design with four replications in three regions (mashhad, ardebil and damavand, iran) during 2003-2004. nine treatments were used. the main-plots were three levels of irrigation: 100%(i1), 80%(i2), and 60%(i3) of crop water requirement. three planting pattern were used in the sub plots: b1, the distance between cultivation rows being 75cm using one drip irrigation lateral line; b2, two cultivation rows with a 35cm distance and one drip irrigation lateral line between rows (distance between laterals = 135cm); and b3, two cultivation rows with a distance of 45cm and one drip irrigation lateral line between rows (the distance between laterals = 150cm). results showed that the b2 planting pattern had the highest total yield and economic yield in three regions. there was a significant difference between the b1 and b3 treatments in ardebil, but no significant difference in mashhad and damavand. the b2 had the longest tube yield (35-55mm) for the three regions. water use efficiency (wue) of the b2 planting pattern was greater than for the b1 and b3, the difference being significant in ardebil and damavand, but not in mashhad. water stress led to a reduction of the total tube yield, economic yield and wue. the highest tube yield (35-55 and more than 55mm) was measured when total crop water requirement (i1) was applied and showed a significant difference with i2 and i3 in mashhad and ardebil. there was same results for wue. accordingly, drip irrigation was suggested for potato cultivation when 100% of crop water requirement was applied.