Behavior of cassava cultivars with different foliage characteristics grown under different plant populations

Abstract

A field study was conducted at the east coast of the State of Ceará, Brazil, from march 1978 to august 1979, which included two growing seasons. The objective was to study the behavior of two cassava cultivars (Manihot esculenta Crantz), Do Céu and Saracura with broad and narrow lobed leaves, respectively, grown under varying population densities. The pattern of the plant dry matter accumulation and distribution was also studied. The Leaf Area index (IAN showed maximum values in the 4th and 15th months after planting, corresponding to the rainy seasons of 1978 and 1979. Cultivar Saracura showed higher IAF in all population densities, with the highest differences taking placa during the two rainy seasons. The IAF followed closely the amount of rainfall in the experimental area. Cultivar 'Saracura' had considerably smaller leaves than cultivar 'Do Céu'. Both cultivar showed larger leaves in the first growing season. Cultivar 'Saracura' slightly outyielded 'Do Céu' in total biomass. A greater proportion of the dry matter was diverted into the root tubers of 'Saracura' than in 'Do Céu'. As a consequence 'Saracura' had higher harvest index during alt stages of growth. For both cultivars the harvest index was highest in the 7th month after planting. The best performance of cultivar 'Saracura' does not seem to be related to its narrow leaf lobes but to the ability of this cultivar to rapidly produce a high IAF associated to the capacity to divert large proportion of dry matter to the root tubers. For both cultivars it was observed that a reduction in the proportion of dry matter diverted to the roots with the increase in plant population.