Tapping panel dryness is an important limiting factor in rubber productivity of Hevea brasiliensis. In order to assess the sensitivity to this syndrome, the effect of two intensive latex harvesting technologies on moderately metabolized GT1 clone, has been studied in the South-Eastern region of Côte d'Ivoire. The rubber trees were planted according to the experimental mono-tree device, "One tree one plot design" a tree constituting a repetition, and 31 trees per treatment, selected on circumference and health status criteria. The parameters measured were rubber production, circumference increase, physiological profile and tapping panel dryness sensitivity. The results showed that induction of tapping panel dryness in latex harvesting system, S/2 d/3 6d/7 ET 10 % Pa 1 (1) 1/ w) was significantly low (0.18 ± 0,22 %) than that of the control (S d/1 6d/7 unstimulated, 1.43 ± 1.45 %). Productivity of this particular system was also good (62 ± 16.32 g.a-1.s-1) and it especially has less stress that can cause physiological fatigue, or even the notch dry. Otherwise, Rubber production, radial vegetative growth, physiological parameters of the latex and the tapping panel dryness rate were influenced by the two treatments applied to GT 1. In addition, the medium and high sucrose contents (16.5 ± 3.01%) and thiol group (0.51 ± 0.13 mmol.l-1) of the latex in the treatment (S/2 d/3 6d/7 ET 10% Pa 1 (1) 1 / w), were instrumental in the response to this stimulation. The sensitivity to the tapping panel dryness is in very close linear relation with the harvest intensity of the latex to which the GT 1 clone has been subjected. These results corroborate and confirm the moderate sensitivity to the tapping panel dryness of GT 1 clone.
The cultivated rubber clones are sensitive to latex harvesting regimes according to their laticiferous metabolism. Thus, in order to determine the best latex harvesting systems of clones with active or rapid metabolism (IRCA 18, IRCA 130, PB 235, PB 260 and PB 330), six latex harvesting technologies are applied to them in a bulk statistical device from Fisher to four rehearsals. The rubber is tapped in downward half spiral stimulated or not for nine years after the opening of the tapping panel. The agronomic parameters (production, vegetative growth), the tapping panel dryness and those of the latex micro diagnosis were evaluated. The results indicate that these clones independently of the latex harvesting system have good rubber productivity (2310 kg.ha -1 .y -1 ) with good radial vegetative growth (2.9 cm.y -1 ). Their trees show a wellbalanced physiological profile and an acceptable sensitivity to the tapping panel dryness (4.9%). However, the physiological index, the bark consumption and the sensitivity to the tapping panel dryness lead to retain the latex harvesting technologies " S/2 d3 6d/7 Pa1(1) ET2.5% 4/y and S/2 d4 6d/7 Pa1(1) ET2.5% 4/y " for the best. This index, favorably influencing the choice of technologies adapted to clones with active metabolism, contributes to the modern and efficient management of a rubber plantation.
The improvement of pineapple (Ananas comosus var. Smooth Cayenne) by means of in vitro culture is less studied in Côte d'Ivoire despite the importance of this plant for this country’s economy. Our work consisted in highlighting nature and concentration effects of carbohydrates on the proliferation of calli in pineapple as a prelude to efficient embryogenesis. Callus proliferation was carried out from the base of pineapple vitroplants leaves. Thirty (30) explants were cultured on the tested culture medium. MS medium (micro- and macro elements of Murashige and Skoog) supplemented with vitamin Gamborg B5 was used as base medium to which were added 0.05 mg/L BAP, 3 mg/L picloram, 2 mg/L glycine, 1,000 mg/L glutamine, 100 mg/L casein hydrolyzate and 30 g/L carbohydrate. Sucrose was tested at different concentrations (20, 25, 30, 35 and 40 g/L). The results revealed that callus proliferation is strongly influenced (p ˂ 0.0001) by nature and concentration of carbohydrate. Sucrose with the highest dry matter content (61.34 mg) has a higher callogenic potential than the other studied carbohydrates. The concentration of 30 g/L sucrose significantly improved the calli proliferation in pineapple. Galactose and maltose were less favorable to proliferation.
Latex harvesting is the most costly activity in natural rubber production and the shortage of available skill and unstable latex harvester are the main factor affecting in Rubber cultivation and its lead to increase cost of production. Low frequency system (LFT) with the hormonal stimulation is a solution to solve this problem that minimize the cost of latex harvesting. Therefore, a study was conducted for nine years on production systems that minimize the cost of latex harvesting in southwestern Côte d'Ivoire with clones IRCA 130, GT 1 and PB 217 of Hevea brasiliensis. These production systems differ from each other by an increase in tapping frequency, in comparison with the standard tapping (d3) on the above clones in southwestern Côte d'Ivoire. The results indicated that production systems that minimize the cost of latex harvesting admittedly resulted in losses of rubber yield per hectare per year from 1 to 37%, but improved the yield per tree per tapping as well as the productivity of the tapper from 20 to 46%, in year. Moreover, these systems contributed to the improvement of the vegetative growth of trees and kept the rate of dry trees in low level (less than 7%). Furthermore, these systems also helped to reduce the cost of tapping labor from 1 to 50%, as well as operating costs from 2 to 47%, in comparison with European Scientific Journal October 2018 edition Vol.14, No.30 ISSN: 1857 – 7881 (Print) e - ISSN 1857- 7431 191 the standard tapping (d3). Finally, in the context of a shortage of tapping labor, these systems help increase the farmer’s profit margin from 26% to 113%, as well as the tapper’s income from 26% to 89%. Therefore, it appears that the use of low frequency harvesting system with the appropriate stimulants appears as a solution to minimize latex harvesting cost and unavailability of harvesters in rubber cultivation.
Land preparation method and preceding crops affect the evolution of rubber trees. Its ignorance and/or poor execution do not allow the efficient development of the agronomic and economic potentialities of plantations. In order to remove this constraint, a study was undertaken in southwestern Côte d'Ivoire. The rubber trees were planted at 510 trees/ha according to a Fisherblock experimental design, of six preceding crop treatments with three repetitions. Only one latex harvesting system was applied (S/2 d/4 6d/7 ET 2.5% Pa 1 (1) 6/y). The parameters measured were rubber yield, annual average girth increment, physiological profile, sensitivity to tapping panel dryness and sensitivity to root rot caused by the genus Fomes. The results showed that the rate of rubber trees found in the plots was good (90.73± 0.47 %) and had varied with land preparation method depending on the preceding crops. Vegetative growth at tapping (2.05±1.36 cm.year -1 ), and average rubber yield (2053±179 kg.ha-1 .year -1 ) and the rate of tree loss due to the genus Fomes (8.33±0.42%) were influenced by land preparation method. The good productivity, the good physiological state of the rubber trees were characterized by a well balanced physiological profile and a tapping panel dryness rate (3.60 ± 1.74%), independently of treatments. The Agroeconomic results showed that mechanically prepared fallow (813641 FCFA.ha-1 .year -1 ) was the best preceding crop and land preparation method. This technical result has two main interests for the national rubber-growing industry, since it actively participates in the national policy for fighting against deforestation but also contributes to the establishment of a secondary forest by the attributes of the rubber-growing plant cover.
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