Influence of Downward Tapping Delay on Agronomic Parameters of Upward Tapping Rubber Trees
Moro Affia Perpétue *
Université Nangui Abrogoua, UFR des Sciences de la Nature, Laboratoire de Biologie et Amélioration des Productions Végétales, BP 801 Abidjan 02, Côte d’Ivoire.
Kouakou N’ guessan Kan Pulchérie
Université Nangui Abrogoua, UFR des Sciences de la Nature, Laboratoire de Biologie et Amélioration des Productions Végétales, BP 801 Abidjan 02, Côte d’Ivoire.
Diarassouba Moussa
Ecole Nationale Supérieure d’Abidjan, Physiologie Végétale, 08 BP 10 Abidjan 08, Côte d’Ivoire.
Adou Bini Yao Christophe
Centre National de Recherche Agronomique (CNRA), Laboratoire d’Agrophysiologie Végétale, Programme Palmier à huile, Station de la Mé, 01 BP 1536 Abidjan, Côte d’Ivoire.
Konan Djezou
Centre National de Recherche Agronomique (CNRA), Laboratoire d’Agrophysiologie Végétale, Programme Hévéa, Station de Bimbresso, 01 BP 1536 Abidjan, Côte d’Ivoire.
Koffi Antoine
Université Jean Lorougnon Guédé, UFR Agroforesterie, Laboratoire de la Production Agricole, BP 150 Daloa, Côte d’Ivoire.
Kouakou Tanoh Hilaire
Université Nangui Abrogoua, UFR des Sciences de la Nature, Laboratoire de Biologie et Amélioration des Productions Végétales, BP 801 Abidjan 02, Côte d’Ivoire.
Obouayeba Samuel
Centre National de Recherche Agronomique (CNRA), Laboratoire d’Agrophysiologie Végétale, Programme Hévéa, Station de Bimbresso, 01 BP 1536 Abidjan, Côte d’Ivoire.
*Author to whom correspondence should be addressed.
Abstract
The nine-year period of downward tapping prior to upward tapping is often considered too long and irrelevant. Thus, a study was carried out to determine the minimum time needed for downward tapping for which the agronomic parameters (rubber production, vegetative growth) of the rubber trees could best be expressed in upward tapping. Clones with slow (PB 217 and IRCA 41), moderate (GT 1) and fast (PB 260 and IRCA 18) metabolisms were used as plant material in the experiments carried out in Gagnoa, Bettié, Daoukro, San Pedro and Divo. The rubber trees were tapped in a half-spiral downward direction at different times followed by quarter-spiral upward or upward tapping. The experimental design was a Fisher block design with 9 treatments and 4 replications. The results showed that upward tapping preceded by downward tapping for 5 and/or 6 years was the best regardless of the metabolic activity class of the clone. Rubber production expressed in kg.ha-1. year-1 [Slow (5y-2675 ± 79) (6y-2488 ± 59) (T9y-2238 ± 45); Moderate ((5y-5417 ± 127) (6y-5094 ± 141) (T9y-3993 ± 58); Fast (5y-5210 ± 239) (6y-4733 ± 500) (T9y-3723 ± 245)] resulting from these upward tappings increased with an increasing gradient of clone metabolism without, however, detrimental to vegetative growth (cm. yr-1) [Slow (5 yr-3.90 ± 1.27) (6 yr-4.05 ± 1.48) (T9 yr-3.40 ± 1.13); Moderate ((5 yr-3.02 ± 0.25) (6 yr-2.80 ± 0.05) (T9 yr-2.39 ± 0.02); Fast (5 yr-4.27 ± 0.42) (6 yr-3.97 ± 0.28) (T9 yr-3.60 ± 0.05)]. These results show that upward tapping in year 6 is more advantageous than tapping in year 10.
Keywords: Hevea brasiliensis, PB 217, IRCA 41, GT 1, PB 260 and IRCA 18, rubber production, vegetative growth, Ivory Coast