Yam is a tuber cultivated mainly in West Africa. Its culture faces biological and non-biological constraints of climatic types especially. The increasingly high temperatures as well as the bad spatio-temporal distribution accentuate the aridity of the grounds which considerably disturb the development even the production of yam. The objective of this study was to compare the morphophysiological adaptation responses of yam morphotypes subjected to water stress and to determine the portion of the seedling and the water regime suitable for a cultivation of yam in semi-arid zones. even arid. To do this, two morphotypes of yam «waogo» (Dioscorea alata) and «nyù» (D. cayenensis - D. rotundata complex) were grown in pots in real conditions. The tubers of each morphotype were divided into three portions and then subjected to three water regimes. Environmental and morphophysiological parameters were noted during the study.For all the parameters studied, the results show that the «nyù» is more tolerant of water deficit than the «waogo» with a larger root biomass and leaf area and lower transpiration. This study reveals that depending on the portion of the seed used and water regime, «nyù» and «waogo» have differentiated behaviors.

Cowpea (Vigna unguiculata L.Walp.) is a basic food product which is cultivated in the savannas of west Africa. Its cultivation is confronted to biotic and abiotic constraints. The abiotic constraints are primarily of climatic types (recorded rainfall, temperature). The bad spatio-temporal distribution of recorded rainfall as well as the high temperatures accentuate the drought which blocks the production of cowpea. The aim of the study is to identify the varieties of cowpea that is adapted to the cultivation of dry season, (ii) to determine the suitable hydrous mode and its (their) period(s) in the year favorable to the cultivation of dry season of cowpea. Thus, two varieties of cowpea- KN1 and KVX 61.1 -were cultivated in pots of six (06) liters in real medium, during the hot period of the year. The trials were separated by a fifteen (15) days interval. Each variety was subjected to three hydrous modes from the 14th days after sowing. The environmental, morphological and agronomic parameters were noted during the study. The results revealed that the temperature gradually turned down and the relative humidity and the productivity of KVX 61.1 have gradually increased until the end of the study. . Variety KN1 was illustrated by the absence of flowering. The report biomass root on air biomass evolved according to the temperature. This study reveals that KVX 61.1 sown and sprint led starting from March 26th every two makes it possible to obtain a rather good production of pods.