The study of tolerance of 25 wheat cultivars to Total herbicide

Nowadays wheat cultivars with high competition ability and resistance to herbicides are important in weed managment. This experiment did in order to evaluate 25 wheat cultivars resistance to Total herbicide in 94_95 at the research field of Mohaghegh Ardabili. The tretment of experiment consist of 25wheat cultivars (Alvand, Heydari, Sayson, Narin, Beckersrvshen, Mahdavi, Pishtaz, Pishgam, Bam, Aria, Kaskoogen, Sivand, Sirvan, Homeland, Arg, Behrang, Shabrang, Zare, Pars, Urum, Bahar, Marvdasht, Shiraz, Chamran, Ofuog) and total (40gr/hec). The experiment performed in randomized complete block design in three replication. The results of the experiment showed that the evaluation of wheat damage in the three stages of sampling was significant. Most of the damage was related to Pars cultivar and the least damage was due to Cascogen and Orum. However, Pars cultivar had the most control of herbivores and the lowest control of herbivorous was in Kaskozhen. The cultivars with higher weed control index significantly affected wheat height. The results of the comparison of mean values showed that the highest wheat height was related to Narin, Behrang, Horizon and lowest height of Shabrang cultivar. Grain number per spike, grain yield, spike length, 1000 grain weight were affected by total herbicide application, but biological yield of wheat cultivars was not significant. For the number of spikes per unit area, the results showed that the highest amount of this trait was for Mahdavi and Syson cultivars and the lowest value was obtained for Behrang cultivar. The number of seeds per spike showed the highest for Syson cultivar and the lowest value was obtained for Shabrang variety. Regarding the fact that Shabrang cultivar had the lowest herbaceous control index and there was a high competition between herbivorous and Shabrang variety, number of spikes and number of seeds per spike decreased. The highest 1000-seed weight belonged to Behrang and Aria cultivars (40- 42g) and the lowest 1000-seed weight was obtained for horse and citrus cultivars (28-30 grams). The highest grain yield belonged to Behrang cultivars (3800 to 4500 kg ha-1) and the lowest grain yield was obtained from Shabrang and Aria (1700-1800 kg ha-1) cultivars. The highest harvest index was obtained from Behrang cultivars (53%) and the lowest harvest index was obtained from Shabrang (22%) cultivars. At the intervals of 10 days after spraying, the highest chlorophyll content was observed for Bam cultivar and the lowest chlorophyll content was observed 10 days after spraying in Behrang, Sayson and Shiraz cultivars. The results of the experiment indicate that the use of total herbicide changes the conditions of the weed competition with wheat. Different varieties of wheat have different tolerance to herbicide due to their physiological conditions. Keywords: Weed control index, eye damage, number of seeds per spike, grain yield, spike length, 1000 grain weight