The effect of sowing date and animal manure application on some growth traits of yarrow (Achillea millefolium L.) under climatic conditions of Kermanshah

Medicinal plants have a significant contribution in the production of existing medicines. Yarrow plant is one of the most important medicinal plants. The goal of the global community is to move towards sustainable agriculture, in order to reduce or eliminate chemical inputs and achieve performance stability and reduce adverse environmental effects. Sowing date is one of the factors that play a fundamental role in achieving the right conditions during the growth period to obtain the maximum yield of the plant. Finding the right level of fertilizer and the best sowing date it will help farmers to grow it as well as possible Therefore, the purpose of this research was to investigate the effect of sowing date and fertilizer levels on some growth characteristics of yarrow. This research was carried out in the organic agriculture form in Campus of Agriculture and Natural Resources at Razi University in 2019-2020. The experiment was conducted in the form of split plots based on complete blocks design in three replications. Experimental treatments included four levels of farmyard manure (zero, 10, 20, 30 ton ha-1) as the main factor and three sowing dates (April 15, May 4, and May 24) as sub factors. The examined traits included leaf area index, total dry weight, crop growth rate, relative growth rate and grain yield. Traits were measured in two ways: destructive and final sampling. Destructive traits started about 50 days after planting the seedlings in the ground. To calculate the crop growth rate and relative growth rate the derivation method from the total dry weight equation was used. At the time of harvest, in order to measure the yield after removing the marginal effects, 5 plants were randomly picked from each plot and then the plants were transferred to the laboratory. After drying the samples, the grain yield was measured. Finally, data analysis was done using SAS software version 4.9 and Duncan's multiple range test (P≤0.05) was used to compare the mean of the data. The results showed that with the increase in the levels of animal manure application, the leaf area index, the crop growth rate and the total dry weight increased in all three sowing dates. So that the highest (3.15, 5.83 g m-2 d-1 and 810 g m-2, respectively) and the lowest leaf area index, crop growth rate and total dry weight (1.185, 0.44 g m-2 d-1 and 87 g m-2, respectively) were observed the treatment of the first sowing date and 30 ton ha-1 animal manure application and the treatment of the third sowing date and 0 ton ha-1 animal manure application, respectively. Animal manure had a significant effect on grain yield so the highest (1.7 g m-2) and the lowest (0.2 g m-2) grain yield were observed in the treatment of the first sowing date and 30 ton ha-1 of animal manure application and 0 ton ha-1 animal manure application and the third sowing date, respectively. The results showed that for the yarrow plant, with the increase of sheep manure up to 30 tons per hectare and the sowing date of April 15, the studied growth characteristics such as leaf area index, total dry weight, crop growth rate, and relative growth ratio increased. Also, the sowing date of April 15 and the use of 30 tons of manure per hectare had a significant effect on the seed yield. According to the obtained results, the sowing date of April 15 was suitable which increased the growth period of yarrow plant. Therefore, using animal manures instead of chemical fertilizers can be a suitable alternative to increase yield and avoid the environmental harm of chemical fertilizers.