Analysis of cassava growth at different harvest times and planting densities

Abstract

Vegetative canopy architecture, and plant population density, has a direct influence on the growth and production of crops. The objective of this study was to evaluate the growth of four cassava cultivars of contrasting canopies, in four population densities, during two vegetative cycles. A randomized complete block design was used in a subdivided plot scheme, with two replications, with the population densities in the plots and harvesting times in the subplots. 'Branca de Santa Catarina' (BSC), 'IAC 13', 'IAC 14-18' and 'Fibra' were collected every four months, beginning at 120 and ending at 720 days after planting (DAP). Primary data on dry matter and leaf area were calculated. The total dry mass (W t ), leaf area ratio (L a ), leaf area index (L), relative growth rate (R w ), and net assimilation rate (E a ) were calculated based on the primary data. All cultivars accumulated more total dry mass (W t ) at lower planting densities. The plants reached a higher leaf area ratio (L a ) 120 days after planting. In the second vegetative cycle, the four cultivars, independently of the population, presented a reduction of assimilate translocation to the leaves. Relative growth rate (R w ) of the cultivars varied strongly with the plant population only in the second cycle. 'IAC 14-18' showed greater dependence on spacing, and 'Fibra' less dependence. Growth (R w ) and assimilatory (E a ) rates decreased at the end of the first cycle, then increased slowly until the end of the second cycle of vegetation.