BIOMASS PRODUCTION AND DIAMETER GROWTH OF 9 HALF-SIB FAMILIES OF MESQUITE (PROSOPIS-GLANDULOSA VAR GLANDULOSA) AND A FAST-GROWING PROSOPIS-ALBA HALF-SIB FAMILY GROWN IN TEXAS

In a 10 year field trial involving nine half-sib families of native south Texas mesquite (Prosopis glandulosa var. glandulosa) and one fast growing Prosopis alba half-sib family, 0166, no significant differences in biomass productivity were found between native P. glandulosa families. The biomass productivity of P. alba 0166 was significantly greater than that of native P. glandulosa families in the first 4 years of the trial. However, the survival of P. alba 0166 over the 10 year period was 17%, versus 84% for the native P. glandulosa families, owing to severe freezes in 1983 and 1989. The two P. glandulosa families with the highest biomass productivities over the 10 year trial were the progeny of the two largest mother trees of the original nine. The P. glandulosa family from a small mother tree had the lowest biomass productivity. The nine native south Texas P. glandulosa families had an average basal diameter growth rate of 1.67 cm year-1 and average dry biomass productivity of 6.9 t ha-1 year-1. In 1986, a year of average annual rainfall preceded by a year of high annual rainfall, the mean basal diameter growth rate for native P. glandulosa families was 2.83 cm year-1. These diameter growth rates compare favourably with the diameter growth rates of commercial hardwood timber species grown in the USA.