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order to determine the effect of two row widths (55 and 70 cm) and tour planting densities (3.0, 4.5, 6.0, and 7.5 plants per unit area) on the physiological characteristics of three potato varieties (Draga, Aoula, and
Kasmoos), a statistical split-split plot experiment in randomized complete block design with four replications was conducted during the 1996 growing
season at the Research Station Of Agricultural Faculty Of The Islamic Azad
University Of Ardabi1. Sampling was done in 31, 59, 87, 110, 127, and 156 days
after planting (DAP), with two plants from each plot. Several polynomial models were tested to ascertain the models which can have the best least
squares fit to the observed data for total dry weight (TDW), leaf dry weight (LDW), tuber dry weight (TUDW), and leaf area index (LAI) relative to time
(T). Nine growth analysis parameters consistang of crop growth rate (CGR),
tuber growth rate (TUGR), relative growth rate (RGR), relative tuber growth
rate (RTUGR) , net assimilation rate (NAR) , specific leaf area (SLA), leaf arearatio (LAR), leaf area index (LAI), and leaf area duration (LAD) were
computed. Maximum CGR was obtained with Kasmoos cv., row width 50 cm and plant density of 6.0 pl/m2 as 14.03, 9.00, and 10.33 glm2/day respectively in 70 days after planting. Optimum LA! for above treatment combination in this
region was 1.95. In all treatments, NAR decreased in proportion to time. However, with plants under high density, N AR was high. Furthermore these plants are of high efficiency in assimilation. The highest TUGR went to Aoula
cv. (9.602 glm2/day) in planting pattern 55 cm (8.482 glm2/day) and planting
density of 7.5 pl/m2 (10.443 glm2/day). In general, Kasmoos cv. (2068.63 glm2)
with row width of 70 cm (2041.58 glm2) and planting density of 6.0 pl/m2 (2331.68 glm2) was the best and suggestable treatment combination for the Ardabil region.