Determination of compressive failure characteristics of physic nut (Jatropha curcas L.) seed coat

The compressive failure characteristics of the physic nut (Jatropha curcas L.) seed coat were determined as affected by factors such as the moisture content, the manner of orientation upon compression, and the physical dimension of the seeds. The moisture content of the seeds varied from 3%, 10% and 45%. The manner of orientation upon compression was set to be laterally or longitudinally. The length and thickness of the seeds were also measured to determine if they have significant effects on the force required to break the physic nut seed coat. It was found out that moisture content and the manner of orientation upon compression of the seeds significantly affected the force required to break the seed coat. On the other hand, it was also found out that the physical dimension, the length and thickness, of the seeds did not affect the failure force of the seed coat. As the moisture content decreased, the force required to break the seed coat increased. It was also observed that the larger force was required to break the seed coat, having the same moisture content, at longitudinal orientation compared to lateral orientation of compression. On the average, at 3% moisture content, the failure force of the seeds at lateral orientation was 99.67 deg N and at longitudinal orientation of compression was 163.81 deg N. At moisture content level of 10%, the average failure force obtained to break the seed coat at lateral orientation was 96.92 deg N and at longitudinal orientation was 159.61 deg N. The seeds having 45% moisture content exhibits an average failure force of 94.70 deg N at lateral orientation and 144.78 deg N at longitudinal orientation. The manner of breakage of the seed coat was observed to be longitudinally, or from the apex of the seed to the upper tip, whether the seeds were compressed in lateral or longitudinal orientation.