Morphological Comparison and Content of Oilseeds Jatropha curcas (L.) Ungrafted and Grafted on Rootstock of Jatropha cinerea (Ortega) Muell. Arg.

Jatropha curcas is native of Mexico and is distributed in the forests of coastal regions. The plants have shown potential for the production of biofuel, and defatted kernel meal of Jatropha non-toxic species can also be used as animal feed; because the seed (kernel) is rich in lipids (55-58%) and raw protein (31-34.5%). Jatropha cinerea is another species distributed in wild populations of northwestern Mexico, which can withstand long drought periods and tolerate up to 100 mM of NaCl. It is believed that the latex is useful to cure all kinds of wounds and burns.

J. curcas and J. cinerea are mainly spread by seed and vegetatively by cuttings, in vitro culture, and grafting mention that rootstocks of J. cinerea could be used as an alternative to reduce hydric and saline stress of grafted plants J. curcas. The search for new renewable alternatives is growing, of which oil is one of the frontrunners. However, to date there are no studies of J. curcas in relation to grafted plants on J. cinerea rootstock and the oil content in the seeds.

The aim of this study was to compare J. curcas ungrafted and grafted on rootstock of J. cinerea morphologically and their oilseed content.

The experiment was performed in the Laboratory of Plant Biotechnology at CIBNOR, La Paz, Baja California Sur, Mexico. Two-month ungrafted and grafted seedlings were transferred to 5-L pots with Sogemix® substrate and perlite (75% and 25%, V/V, respectively) and planted subsequently in an experimental field. The observations started 3 months after grafting, using 4 ungrafted and 4 grafted plants. The parameters observed included: plant growth, height, and stem diameter above the graft union.

Ten months after grafting, the statistical analysis showed significant differences in height between grafted and non-grafted plants but not on stem diameter. The high compatibility of grafted plants showed similar growth in grafted and non-grafted plants. Jatropha ungrafted and grafted differed significantly in weight, but they were similar in diameter and length. Oil yield did not differ significantly; however, more oil could be obtained if we consider that the seeds of grafted plants are heavier.

The grafting method improves Jatropha curcas height and seed weight, and it does not affect germ oil percentage. Therefore, the use of grafted plants is an excellent option for plantation establishment and production in less time with homogeneous yields.