Enhancing Clonal Multiplication of Prosopis juliflora and Prosopis cineraria for Dryland Restoration and Genetic Resource Conservation

Abstract

Prosopis juliflora and Prosopis cineraria are ecologically and economically important tree species that are found throughout arid and semi-arid regions of the world. However, large-scale propagation of unique genotypes is hampered due to physical seed dormancy, inconsistent germination, inbreeding depression, and genetic variability among seed-derived seedlings.  The effects of two auxins, naphthalene acetic acid (NAA) and indole-3-butyric acid (IBA), administered at concentrations of 3000, 4000, and 5000 ppm, on adventitious root formation and shoot growth of stem cuttings of P. juliflora and P. cineraria were assessed in this study. Effects of two rooting substrates i.e. sandy loam soil and a mixture of sand, leaf compost, and soil (1:1:1) were also evaluated. Results showed a significant difference between species and treatments in terms of root length, shoot length, and root number. IBA produced the best root and shoot development, continuously outperforming NAA, especially at 5000 ppm. As compared to sandy loam alone, the combined rooting substrate further improved rooting performance. P. cineraria showed a more fibrous root system and reached maximum root production under the same treatment combination, but P. juliflora showed the greatest root length (18 cm) and root production in cuttings treated with 5000 ppm IBA grown in the mixed medium. Auxin application significantly enhanced root quality and vegetative growth, even while rooting percentages differed only slightly between treatments. These results show that the conservation, restoration, and deployment of superior Prosopis genotypes in dryland environments can be accomplished practically and economically by auxin-mediated clonal multiplication.