Mineral imbalance in hevea brasiliensis micro‐cuttings: Relation with in vitro multiplication and acclimatization

Abstract

The mineral composition of Hevea brasiliensis shoots was analyzed at different stages of the microcutting procedure from mother plants grown in greenhouses to rooted microcuttings at the acclimatization stage. Compared to the mineral status of the mother plants, a mineral imbalance was noticed in shoots right from the in vitro establishment phase. Phosphorus (P), potassium (K), sodium (Na), chloride (Cl), and zinc (Zn) contents increased, while calcium (Ca), magnesium (Mg), iron (Fe), and copper (Cu) diminished, resulting in a substantial modification to the mineral balance. The N: P, N: K, Mg: P and K: Na ratios were very low, whereas the K: Mg, K: P, and K: Ca ratios were very high. During the multiplication phase, the N: P ratio returned virtually to its initial value but the other ratios remained modified. A mineral analysis of shoots after three years multiplication in vitro revealed a very low N: P ratio, a very high K: Ca ratio and a normal K: Na ratio. The same results were obtained right from the initial culture cycles on shoots developed in vitro from mother plants with a high multiplication potential. These results are discussed and lead us to consider the N: P, K: Ca, and K: Na ratios as potential markers of Hevea brasiliensis multiplication ability in vitro. During the rooting phase, the Mg: P and K: Ca ratios returned to their normal values, whereas the other ratios returned to normal values on formation of the second leaf flush ex‐vitro.