Dry matter production and distribution model in intercropped Cassava

English

Different stands of two contrasting maize (Zea mays L.) varieties and two equally contrasting cassava (ManiJwt esculenta Cranz) varieties were established as intercrops in experiments at Fumesua and Kwadaso near Kumasi (6° 43' N, 1°36' W) in 198611ld 1987. The main objectives involved the comparison of harvest index (HI), efficiency of storage root production (ESRP), and initial start of starch accumulation (ISS) of cassava intercropped and monocropped. The determination of m, ESRP, and ISS of the two cassava cultiVirs coqld then be used to visualize genetic differences IIld the effect of the environment on dry matter distribution. The determination of the proportion of dry matter assimilation at a particular time, distributed to the stol'llge orgllls of intercropped cassava, was also the other objective in order to, describe the distribution of dry matter over storaae roots of cassava. Asymptotic relationships were established between dry weights and harvest indices, indicating that harvesting efficiency, although increased with dry matter increase, became constant Il1d did not ehIl1ge with furthtr increase in total dry matter. This should. be!of interest beeause of the economics of dry'matter increase beyond this point The dry matter lit which the harvesting efficieJlcy became constant, ESRP, seemed not to be influenced by only genotype, but also by cropping practise and season. Partitioning of assimilates to the storage roots of intercropped cassava was observed to be bimodal, IIlci closely followed the pattern of radiation income for the Kumasi area. Sink size IIld activity as well as soil moisture content and, presumably, the plant water potential, were also important factors in the partitioning of current dry matter gains into the storaae roots.

Asafu-Agyei, J. N.; Osafo, D. M.