Grazing intensity and frequency on seasonal biomass production in jojoba (Simmondsia chinesis)

Two trials were conducted to evaluate the effect of annual grazing (pruning ) and seasonal grazing (four times a year) on total green foliage weight (T GFW), total dry foliage weight (TDFW), culm dry weight (CDW), leaf dry weig ht (LDW), total leaf area (TLA), specific leaf area (SLA) and N-content (pr otein) of both culms and leaves. Three grazing intensities (pruning 25, 50 and 75% of vegetative growth) were evaluated in each trial. Data taken at t he end of each of eight consecutive seasons (from 21/6/94 until 21/3/96) re vealed differences (P< 0.05) among seasons for all of the traits studied in the annual grazing trial (both years, for SLA) and for TGFW, SLA and N-con tent of leaves and culms in the first year and for TLA in both years in the seasonal grazing trial. The interaction of season and pruning intensity in the annual grazing trial significantly affected TGFW, TDFW, CDW and LDW in the first year of the study. Dry matter accumulation, under all grazing in tensities, progressively increased with plant age under annual grazing but progressively decreased with plant age under seasonal (repeated) grazing pr actices. Estimates of N-content over the grazing intensities ranged from 2. 61% to 3.00% for leaves and from 1.70% to 2.14% for culms over the grazing trials. Thus, rotational annual grazing of jojoba will ensure the availabil ity of high yields of high quality forage throughout the year.