Influence of 2,4-dichloro Phenoxy Acetic Acid on Seeds Germination and Early Growth of Mesquite (Prosopis juliflora Swarz) DC Seedlings

This study was conducted to evaluate the effect of 2,4-dichloro phenoxy acidic acid (2,4-D) on seed germination and the early growth of mesquite (Prosopis juliflora) seedlings. The three sizes of mesquite at the flowering stage (small, medium, and large) were treated with 2,4-D at different rates (0, 6×103, 12×103, 18×103 and 24×103 mg a.i. / L) dissolved in two solvents (diesel or water), the application method basal bark treatment was used in the two different seasons. The results showed that: the three factors (2,4-D rates, tree sizes, and solvent types) significantly decreased germination percentage with the increase of 2,4-D rate dissolved in diesel with all sizes of trees, while the emergence percentage, radical length, and shoot height were significantly decreased as 2,4-D rate increase dissolved in diesel or water. In the winter season, the root length of seedlings raised from seeds collected from the three tree sizes treated with 2,4-D dissolved in water was significantly decreased as a 2,4-D rate increased, while in the rainy season, the root length was affected with 2,4-D dissolved in diesel. In addition, the effect of 2,4-D rates and solvent types was evaluated for all parameters, the results found that: 2,4-D dissolved in diesel significantly decreased germination percent than the corresponding rates dissolved in water. Emergence percentage and shoot height and radical length were significantly decreased with 2,4-D dissolved in diesel or water compared to their control. In the winter season, the root length is affected by 2,4-D dissolved in water, while in the rainy season affected by 2,4-D dissolved in diesel.