بررسی زیست شناسی و مهار علف هرز قیاق (Sorghum halepense) در مزارع ذرت استان خوزستان

Johnsongrass (Sorghum halepense) is one of the most important weeds in the world. Due to having photosynthetic type C4, strong rhizome, fast growth, shading and allelopathy, is one of the most important weeds in the world. This study was conducted on the botany and biology of the Johnsongrass, it showed that the herbaceous plant is a perennial plant with a height of 50 to 200 cm, With straight and strapping stems, short and fleshy rhizomes with a diameter of one and two centimeters in length. The reproduction is through seeds and rhizomes. Each plant can produce up to 28,000 seeds during its growing season. The seeds are spread in the field by wind, tractors and cultivation tools. In the plowing operation, the rhizomes of the plant are cut into pieces and a new plant grows from each node on the piece, and it leads to multiplication and expansion in the field. This plant has a very strong competition with the corn plant during the growth period and reduces its yield. In Khuzestan province, Johnsongrass seed germination takes place in March and spring and the initial growth of the rhizome is done three to six weeks after germination. Flowering and seeding are simultaneous and from mid-spring to summer, and wintering is done by rhizomes. Different methods to control this perennial weed plant include: 1-mechanical control (repeated disc operations) the remaining single plants in the field are before the formation of seeds and before the cultivation of corn and also at the edge of the fields. Frequent cutting during the growing season is effective for reducing underground reserves, 2-Crop rotation using the cultivation of weed-suffocating plants such as mung bean and Cowpea, soybean and sesame, is agricultural control of this permanent weed. 3-Chemical control using general systemic herbicides such as Glyphosate is recommended in late spring and summer and during the flowering stage of the Johnsongrass (when the direction of the phloem sap is towards the underground organ)). If the control is not done at the time of flowering, the chemical and mechanical control against this permanent weed will take at least 3 years. Nicosulfuron is the most suitable herbicide in corn fields to control the Johnsongrass, but it has shown resistance to this herbicide in some regions.