Tuber response of different ecotypes of purple nutsedge (Cyperus rotundus L.) to temperature and exposure time

Purple nutsedge causes severe damages to vegetable crops in Jiroft, Kahnooj and Birjand. In order to evaluate the effects of high temperature and time of exposure to high temperatures on various ecotypes of purple nutsedge tubers, a factorial experiment was conducted based on randomized complete block design with 3 replications in the Research greenhouse of Birjand University, Iran, in 2016. Experimental factors consisted of 3 ecotypes (Jiroft, Kahnooj and Birjand), different temperatures from 40 to 60°C with 5°C increments, and exposure time including 1, 2, 4, 8, 16, 32 and 64 hours. Results indicated that at all exposure times, 40°C temperature did not affect the growth characteristics of purple nutsedge, while at 45 °C, increasing the exposure time decreased the growth characteristics of purple nutsedge. Three-parameter logistic model estimation showed that  tuber viability (T50) at 45 °C in Jiroft ecotype was 14.64 hours, it decreased to 5.01 hours  at 50 °C. T50 was about 66% lower than for 45 ° C, but it was 19.76 hours in Kahnooj ecotype at 45 °C, while at 50 °C, this parameter decreased to 2.73 hours (86.2%). T50 of Birjand ecotype at 45 °C was 12.90 hours, but at 50 °C, the tubers viability reduced and T50 was 8.91 hours (31% decrease). Results of this research could have an important role in controlling purple nutsedge in vegetable fields.