Mechanical behaviour of plum fruits as affected by preharvest methyl jasmonate applications

Abstract

In this study, the effects of preharvest methyl jasmonate (MeJA) applications on the mechanical behaviour of plum fruits (cv. ‘President’) were investigated.  The mechanical behaviour of plum fruits to compression affected by different harvesting time were determined in terms of rupture force, specific deformation, rupture energy, toughness and rupture power at constant compression speed of 62.4 mm min^-1.  Quasi-static compression loading of plum fruits were conducted at three compression axes (X- Y- and Z- axis) under application of different doses of MeJA before the harvest.  MeJA doses were as  0 mg L^-1, 1,120 mg L^-1, and 2,240 mg L^-1 harvested on the different days viz. 28 August, 4 September and 11 September.   The force required to initiate plum rupture on each axis decreased as MeJA doses increased from 1,120 mg L^-1 MeJA to   2,240 mg L^-1 MeJA.  The rupture energy and rupture power values observed for plum fruits compressed along the Y- axis were higher than the values obtained when testing plum fruits in the X- and Z-axis orientations.  The results indicated that the rupture force and rupture energy along all three axes are highly dependent on MeJA applications.  These finding could therefore be useful in predicting the mechanical behaviour of plum fruits.

Keywords: plum, methyl jasmonate, rupture force, rupture energy, rupture power