Species and provenance trial of Prosopis cineraria and P. pallida
The highest producing provenance in the trial, Peru06, had an average production of 0.8 t dry weight ha-1 y-1. This corresponds to the 1.4 t ha-1 y-1 obtained by the provenance Niger1 in the nearby trial of A. senegal (Trial no. 5 in the arid zone series, also located at Djibo). Comparisons between trials should always be treated with caution because of possible differences in environment between the trials, but the higher production in trial no. 5 may indicate that the full potential of the site is not used by the provenances in the current trial. Another indication that a higher production is possible is the fact that the provenance Burkina08 (A. senegal) in this trial had higher dry weights of the mean trees than the other provenances. Only because of a low survival did the provenance not rank high in total productivity.
Species and provenance differences
None of the provenances of P. cineraria in the trial had a satisfactory growth (below 1 metre), and were thus only assessed for survival. It would be tempting to conclude that the species is not apt for cultivation at sites like Gonsť. It must be noted, however, that provenances from only a part of the natural distribution of the species are included, and that provenances from other areas, such as the southern and central India, might have a better performance. However, until this is proven it seems worthwhile to invest more energy in the testing of other species.
There were no significant differences between the three provenances representing A. senegal and P. pallida. Nevertheless, as mentioned above, there were signs that Burkina08 had a larger average dry weight for the surviving trees, indicating that if survival of the provenance was improved, the production potential would be larger. The largest total production was found in the provenance Peru06, and so it is difficult to give recommendations regarding choice of species and provenances. The growth of A. senegal may be better evaluated in the other trial at Djibo (no. 5), and if P. pallida is to be used, it may be necessary to test a larger array of provenances before giving recommendations. Of the two P. pallida provenances it seems, however, that Peru06 (representing the origin with the highest rainfall) may be the most productive, even though no significant differences were found.