The effect of mature rubber tree-undergrowth yam combination on the agronomic, health and physiological parameters of a rubber tree (Hevea Brasiliensis MÜLL ARG, Euphorbiaceae) clone GT1 in Daloa (West-Central Côte d’Ivoire)

Abstract

A recent study has shown that undergrowth yams can be integrated into mature rubber trees. However, the effect of this combination on the agronomic, health and physiological parameters of rubber tree needs to be assessed. To this end, two accessions of undergrowth yams were grown in the inter-rows of mature rubber trees of clone GT1. The experimental set-up was a Fisher block design with two factors, five treatments and three replications. The parameters measured were girth increment (Incr), rubber yield, tapping panel dryness rate (TPDR), leaf water potential, dry rubber content (DRC), sucrose content, inorganic phosphorus (iP) and thiol content (R-SH). The results showed that the treatments in which undergrowth yams were combined with rubber trees exhibited girth increments of 1.39 cm.yr^− 1, yield of 122.02 g per tree and per tapping (g.t.t^− 1), very low tapping panel dryness rates less than 0.30% and midday leaf water potential of 1.48 MPa statistically identical to those of the control rubber trees. Thus, at the end of the experiment, the associated rubber trees presented a balanced physiological profile similar to that of the control rubber trees, with very high dry matter content (DRC = 48.43%), reflecting high biosynthetic activity in the latex, sucrose availability of 7.09 mmol/l l-1, a high Pi content of 23.46 m.mol.l^− 1 and an average R-SH content of 0.66 m.mol.l^− 1. Undergrowth yam can be cultivated in mature rubber trees without adversely affecting their physiological or agronomic performance.