Light requirements for growth of Prosopis glandulosa seedlings

A greenhouse study was conducted to determine light requirements of Prosopis glandulosa Torr. (mesquite) seedlings. Maximum growth occurred in the highest light intensity tested. Number of leaves, stem length, basal diameter, and above-ground, below-ground, and total dry weight increased as light intensity increased. These parameters except number of leaves and stem length were linearly correlated with light intensity. The root:shoot ratio increased with decreased light intensity in a nonlinear fashion. Prosopis glandulosa appears to be a pioneer species and a heliophyte. However, the lack of P. glandulosa seedlings under P. glandulosa canopies is not sufficiently explained by lower growth rates at reduced light intensities beneath adult tree canopies. Additional factors such as differential herbivory, nutrient requirements, or competition are apparently necessary to more completely explain the lack of seedlings.