Abstract :
This study was conducted to evaluate the effects of residuals, obtained from different parts of bermuda grass (Cynodon dactylonis L.), on yield and yield components of wheat. Therefore, A factorial experiment with three replications was carried out at Islamic Azad University, Tabriz Branch in 2008. Residuals of various parts of bermuda grass (leaf, shoot, root and whole plant) were collected and added to the experimental soil at five levels of 0, 40, 60, 80, and 100 g/m2. The results showed that residuals of different parts of bermuda grass decreased plant height, number of fertile tillers, number of leaves and seeds, spike length, weight of 100 seeds and biomass of wheat. By adding higher residuals to the soil, more losses on all plant characteristics will occur. For example, negative effects of 100g of bermuda grass residuals mixed with the soil resulted in decreasing plant height, leaf number, fertile tiller numbers, spike and peduncle length, seed numbers, 100 kernal weight and biomass by 56.7, 70.6, 20.4, 61.8, 41.7, 75.6, 33.2, and 63.9 %, in comparison with the control, respectively. Yield loss of wheat yield was ranging from 7% to 80.5% and mainly depended on the amount of residuals addeded to the soil. However, the maximum negative effects on wheat plants were observed for root residuals. Since wheat is essentially a strategic crop throught the world, even very small reduction of wheat production in the field due to residuals of bermuda grass or other weeds must be taken into consideration.
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