RESUMO

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 (Wt), leaf area ratio (La), leaf area index (L), relative growth rate (Rw), and net assimilation rate (Ea) were calculated based on the primary data. All cultivars accumulated more total dry mass (Wt) at lower planting densities. The plants reached a higher leaf area ratio (La) 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 (Rw) 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 (Rw) and assimilatory (Ea) rates decreased at the end of the first cycle, then increased slowly until the end of the second cycle of vegetation.(AU)

A arquitetura do dossel vegetativo e a população das plantas têm influência direta no crescimento e na produção das culturas. O objetivo desta pesquisa foi avaliar o crescimento de quatro cultivares de mandioca de dosséis contrastantes em quatro densidades populacionais por dois ciclos vegetativos. Utilizou-se o delineamento em blocos casualizados no esquema de parcelas subdivididas, com duas repetições, sendo as densidades populacionais nas parcelas e épocas de colheita nas subparcelas. Foram estudadas 'Branca de Santa Catarina' (BSC), 'IAC 13', 'IAC 14-18' e 'Fibra' colhidas quadrimestralmente, com início aos 120 e finalizando aos 720 dias após o plantio (DAP). Foram determinados os dados primários massa seca e área foliar. A partir dos dados primários foi aplicada a análise de crescimento e calculada a massa seca total (Wt), razão de área foliar (Fa), índice de área foliar (L), taxa de crescimento relativo (Rw) e a taxa assimilatória liquida (Ea). Todas as cultivares acumularam mais massa seca (Wt) nas menores densidades de plantio. As plantas atingiram maior razão de área foliar (Fa) aos 120 dias após o plantio. No segundo ciclo vegetativo, as quatro cultivares, independentemente da população, apresentaram redução da translocação de assimilados para as folhas. As taxas de crescimento relativo (Rw) das cultivares variaram de maneira mais acentuada com a população de plantas apenas no segundo ciclo. A ‘IAC 14-18 apresentou maior dependência dos espaçamentos e ‘Fibra menor dependência. As taxas de crescimento (Rw) e assimilatórias (Ea) decrescem no final do primeiro ciclo, depois crescem lentamente até o final do segundo ciclo vegetativo.(AU)

Assuntos

RESUMO

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 (Wt), leaf area ratio (La), leaf area index (L), relative growth rate (Rw), and net assimilation rate (Ea) were calculated based on the primary data. All cultivars accumulated more total dry mass (Wt) at lower planting densities. The plants reached a higher leaf area ratio (La) 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 (Rw) 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 (Rw) and assimilatory (Ea) rates decreased at the end of the first cycle, then increased slowly until the end of the second cycle of vegetation.

A arquitetura do dossel vegetativo e a população das plantas têm influência direta no crescimento e na produção das culturas. O objetivo desta pesquisa foi avaliar o crescimento de quatro cultivares de mandioca de dosséis contrastantes em quatro densidades populacionais por dois ciclos vegetativos. Utilizou-se o delineamento em blocos casualizados no esquema de parcelas subdivididas, com duas repetições, sendo as densidades populacionais nas parcelas e épocas de colheita nas subparcelas. Foram estudadas 'Branca de Santa Catarina' (BSC), 'IAC 13', 'IAC 14-18' e 'Fibra' colhidas quadrimestralmente, com início aos 120 e finalizando aos 720 dias após o plantio (DAP). Foram determinados os dados primários massa seca e área foliar. A partir dos dados primários foi aplicada a análise de crescimento e calculada a massa seca total (Wt), razão de área foliar (Fa), índice de área foliar (L), taxa de crescimento relativo (Rw) e a taxa assimilatória liquida (Ea). Todas as cultivares acumularam mais massa seca (Wt) nas menores densidades de plantio. As plantas atingiram maior razão de área foliar (Fa) aos 120 dias após o plantio. No segundo ciclo vegetativo, as quatro cultivares, independentemente da população, apresentaram redução da translocação de assimilados para as folhas. As taxas de crescimento relativo (Rw) das cultivares variaram de maneira mais acentuada com a população de plantas apenas no segundo ciclo. A ‘IAC 14-18’ apresentou maior dependência dos espaçamentos e ‘Fibra’ menor dependência. As taxas de crescimento (Rw) e assimilatórias (Ea) decrescem no final do primeiro ciclo, depois crescem lentamente até o final do segundo ciclo vegetativo.

Assuntos

RESUMO

Cassava (Manihot esculenta Crantz) is a staple food and an important source of starch, and the attributes of its tuberous root largely depend on the variety. The proteome of cassava has been investigated; however, to date, no study has focused on varieties that reveal the molecular basis of phenotypical characteristics. Therefore, we aimed to compare the proteome of the tuberous roots of six cassava varieties that differed in carbohydrates, carotenoids, and resistance to diseases, among other attributes. Two-dimensional gels showed 146 differential spots between the varieties, and the functional roles of some differential proteins were correlated to phenotypic characteristics of the varieties, such as the amount of carbohydrates or carotenoids and the resistance to biotic or abiotic stresses. The results obtained here highlight elements that might help to direct the improvement of new cultivars of cassava, which is an economically and socially relevant crop worldwide.

Assuntos