The potential of mini-grafting for large-scale production of Prosopis alba clones

With the objective to develop rapid, cost-effective asexual propagation methods for elite clones of Prosopis alba, grafting treatments were examined on small (2 mm diameter) seedlings that are easier and more rapid to graft than larger stems. Three techniques were evaluated to seal the wedge graft union (black plastic electrical tape, clear plastic grafting tape, and Parafilm(TM) as used in biochemical laboratories) and two treatments (black plastic tape and water-soluble mastic) were evaluated to seal the distal end of the scion. These graft union/distal end-scaling techniques were examined under and outside a plastic tunnel with intermittent mist to maintain high humidity. All of the treatments were examined under a 65% shade cloth in which the mean and 95% confidence interval of light intensity was 329 +/- 53 mumol m(-2) s(-1) and the mean and 95% confidence interval noon temperatures under and outside the tunnel were 28.8 +/- 1.23degreesC and 26.4 +/- 1.19degreesC, respectively. The maximum percentage grafting of 70% was obtained under the tunnel with a combination of parafilm for the graft union and black mastic to seat the distal end of the scion. Lower successes were obtained from grafts with individual plastic bags outside the tunnel. The maximum rate of 20 graft h(-1) (two people) would represent an additional cost of about $33 ha(-1) for the recommended planting density of 100 trees ha(-1) which would be almost insignificant in the total cost over a 30-year rotation of about $2000. This is the only technique currently available that is sufficiently rapid and reliable for use in establishing commercial clonal plantations of Prosopis alba. (C) 2003 Elsevier Science Ltd. All rights reserved.