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Tokyo University of Agriculture and Technology (2008)

Characteristics of NERICA in Two Different Ecosystems (Upland and Lowland)

RONOUBI GOUWA AMBOUROUE AVARO MICHAEL

Titre : Characteristics of NERICA in Two Different Ecosystems (Upland and Lowland)

Auteur : RONOUBI GOUWA AMBOUROUE AVARO MICHAEL

Université de soutenance : Tokyo University of Agriculture and Technology

Grade : Master’ s Course of Plant Science 2008

Résumé partiel
NERICA (O. sativa x O. glaberrima) is important for rice cultivation in Africa. Many professionals of agriculture and food development are expecting that they would contribute to solve food problem in Africa. In this study some agronomic traits of NERICA1 and NERICA5, growing under upland and lowland ecosystems at same location, were examined. Often, NERICA lines presented some common and different traits behavior under different environment. Tiller number was almost the same in upland and lowland condition for NERICA1, while in NERICA5 showed 1.5 times higher in lowland condition. Nitrogen uptake, through SPAD value, showed different patterns between environments, with similar observation for all genotypes. It seemed that lowland reduced days to 50% heading from 2 to 6 weeks with the highest effect observed in NERICA1. In y ield components, several traits that limited the paddy yield increase, under lowland condition, were identified. For NERICA1, in lowland condition, the overgrowth led to the reduction of the spikelet number per panicle. NERICA5 spikelet number per panicle increased under lowland condition with negative effect on ripen ing percentage (76 to 58%). NERICA1 presented the h igher calculated grain yield (611g m-2) under lowland condition, than that of Koshihikari and the others check genotypes (IRAT and Tchibanga). However, for harvested paddy yield, Koshihikari showed the highest value. Other check genotypes yields (IRAT and Tch ibanga) were also higher than both NERICA, in lowland, with the lowest performance (477g m-2) recorded in NERICA5. The lowest paddy y ield recorded was in Koshihikari under upland condition, which confirmed it’s a strictly lowland ecotype. Under different seeding rates, both NERICA genotypes showed different behaviors. In upland condition, it is clear that NERICA5’s yield tended to decrease with increasing seeding rate. NERICA1 presented an opposite reaction. There was significant interaction (p<0.033) of genotype-environment. An optimum density (10g m-2) was revealed in lowland condition. Once again yields of NERICA1 were superior to those of NERICA5. Irrigation cultivation system (intensification) is effective for increasing NERICA performances as yield are twice more than in upland. However, between the two NERICA, NERICA1 gave the best response under intensification.

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