Importance of grass density and time of planting on Prosopis glandulosa seedling growth

Growth experiments were conducted in a greenhouse with seedlings of Prosopis glandulosa Torr. (honey mesquite) and Cynodon dactylon (L.) Pers. (bermuda grass). Effects of density and time of planting of C. dactylon on growth of P. glandulosa were examined. When one seedling of P. glandulosa was grown with two or more C. dactylon in an additive experiment, aboveground, belowground, and total dry weight of P. glandulosa decreased 84, 71, and 79% respectively. Root: shoot ratios for P. glandulosa increased almost four times from lowest to highest density of C. dactylon. Conversely, P. glandulosa caused a significant reduction in dry weight of C. dactylon but mainly in the lowest grass densities. When P. glandulosa was planted with C. dactylon at the same time, dry weight of P. glandulosa was reduced 83%. If P. glandulosa was planted 2 months after C. dactylon was planted, dry weight of P. glandulosa was reduced 96%. Although P. glandulosa had a negative effect on C. dactylon, the negative effect only occurred when the density of C. dactylon was low or they were planted at the same time. Greenhouse studies suggest that P. glandulosa competes almost equally with C. dactylon, unless there is a large difference in density or a temporal difference in planting. In the field, early growth and establishment of P. glandulosa may require reduced herbaceous plant density or vegetation gaps.