This paper focuses on determining a reduced number of morphological criteria for the differentiation of the five clones (GT 1, PB 217, IRCA 41, 230 and IRCA 331) recommended in Côte d'Ivoire. The general objective is to avoid the clonal mixtures observed in the graft wood garden (GWG) of rubber, which is used to graft planting material used by planters. These clones have been described in two GWG using 27 morphological criteria around the world. For each clone, the description looked at 25 healthy plants of three or four shape of the leaf floors clonal compliance. This was confirmed using microsatellite molecular markers. The results showed that six criteria made it possible to clearly differentiate these five clones: colour of the leaves, the cross-section of the central leaflet, the shape of the leaf floors, the nectariferous glands, the length and orientation of the central petolule. The GT 1 clone is identified by the dark green colour of the leaves and a long petiolule ( 1,4 cm), the PB 217 clone by light green leaves with short petiolule (0.9 cm), and the IRCA 331 clone by a conical shape of the leaf floors, straight petiolules, and flat central leaflets. The IRCA 230 and IRCA 41 clones are distinguished by the abundant and infrequent nectariferous glands, respectively. This investigation should be carried out in other localities with the aim of testing the stability of these six criteria in space and time.
Rubber growing is one of the most important industrial crops in Ivory Coast. In order to achieve a good sustainable rubber crop of Hevea brasiliensis in Ivory Coast, the effect of bleeding at unstimulated d4 frequency on radial vegetative growth was evaluated with 16 clones of Hevea brasiliensis divided into three classes of vegetative growth and metabolic activity, planted in a completely randomized block pattern. Agronomic (vegetative growth and rubber production) and physiological (sucrose and inorganic phosphorus levels) parameters were assessed over nine years. The results obtained showed that bleeding in d4 had a significant impact on the mean annual increase in circumference of bleeding trees (3.04 cm.yr -1 ) relative to that of non-bleeding trees (5.29 cm.yr -1 ). The reduction in growth expressed as a percentage of the vegetative growth potential was estimated at 42.53%. Mean annual circumference increments of unbleeded trees of clones of active (MAC; 5.46 cm.yr -1 ) and moderate (MMC; 4.96 cm.yr -1 ) vegetative and metabolic growth classes are significantly greater than those of bleeding trees of clones of the same classes (3.00 and 2.80 cm.yr -1 ). On the other hand, the average annual increments of the slow vegetative and metabolic growing clones (SMC) are hardly affected by bleeding. The production and reduction in growth were 58.96 g.a -1 .s -1 , 45.06% for MAC, 56.2 g.a -1 .s -1 and 43.55% for SMC, and 39.83 g.a -1 .s -1 and 23.8% for SMC, respectively. A very highly significant polynomial relationship (R 2 = 1) between percent reduction in increment (%RedAcc), rubber production and P/Sac and Pi/Sac ratios was found. The percentage of vegetative growth potential below 50% is a sign that bleeding at the unstimulated d4 frequency is a good indicator for improving the productivity of rubber clones without damaging the physiological state.
This study was carried out to identify protein markers with yield potential and susceptibility to tapping panel dryness (TPD). To achieve this goal, 11 clones, stimulated and non stimulated, yield and susceptibility to TPD were compared. Their lutoid fraction polypeptides were analysed using one and two-dimensional electrophoresis. Susceptibility to TPD appeared as a clonal trait which is not related to yield potential. TPD can occur either in stimulated or non stimulated clones but, overstimulation increase TPD symptoms. Clones PB 235, PB 260 and IRCA 130 are highly susceptible to TPD, whereas IRCA 41, PB 217, AF 261, AVROS 2037 and GT 1 are less susceptible. Productive and less susceptible clones to TPD are characterized by abundant quantity of 35 KDa polypeptide and absence or very small amount of 32 KDa polypeptide. Contrarily, clone susceptible to TPD are characterized by abundant quantity of 32 KDa polypeptide. In unproductive clones (RO 38, TJR 1), 32 KDa protein was more abundant than 35 KDa. Overstimulation induces a decrease of 35 KDa protein intensity. Thus, 32 and 35 KDa polypeptides could be used for identification of Hevea clones yielding potential and susceptibility to TPD.
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