Morphophysiological description of early and late potato clones aiming at adaptation to tropical conditions. / DescriÃÃo morfofisiolÃgica de clones de batata precoces e tardios visando a adaptaÃÃo a condiÃÃes tropicais

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The objective of this research was to study the growth, tuberization and dry matter partitioning to tubers of early and late potato clones during the vegetative growth. Besides, it was studied the viability for using morphophysiological traits as parameters to select clones more adapted to tropical conditions. Two clones from each maturity class were used, CBM 16-15 and CBM 2-21, as early clones, and CBM 22-19 and CBM 2-27 as late clones. The morphophysiological traits used were growth cycle, tuber yield, total number of tubers plant-1, tubersâ mean weight, large-tubersâ mean weight, percentage of large tubers, tuber dry matter content, tuberization speed, canopy total dry matter, dry matter partitioning to tubers, content of chlorophylls a, b and total of the upper and lower canopy parts, leaf area of upper and lower canopy parts, total leaf area, relative growth rate, leaf area duration and net assimilation rate to tubers. Late clones were more productive than early clones at the end of the growth cycle. The higher tuber yield of late clones was due to a more vigorous growth and to the longer duration of the photosynthetically active leaf area, which allows a greater tuberization speed during tuber bulking. Tuber bulking period for late clones was longer which allowed a greater tuber yield at the end of the growth cycle. There was a tendency of late clones to present the stay-green trait classified as type A according to Thomas and Howarth (2000), which is characterized by a late beginning of the senescence process compared to early clones. The results of this study suggest that of one strategy that could be used to increase potato tuber yield in the tropics is the selection for a longer growth cycle. Results also suggest that the morphological traits used in this study are important to evaluate clones more adapted to tropical conditions. The following physiological traits were relevant to differentiate late and early clones and should be used in breeding programs aimed at obtaining clones more adapted to tropical conditions: content of chlorophylls a, b and total of the upper canopy, leaf area, leaf area duration, relative growth rate, and net assimilation rate to tubers.

ASSUNTO(S)

batata clorofila physiological index leaf senescence temperatura lateness leaf area duration dry matter partitioning Ãndices morfofisiolÃgicos duraÃÃo de Ãrea foliar clima tropical net assimilation rate taxa de crescimento relativo stay-green solanum tuberosum ciclo vegetativo Ãndices fisiolÃgicos precoce senescÃncia senescence tropical climate tropical conditions teor de clorofila leaf area altas temperaturas solanum tuberosum tuberization tardio taxa assimilatÃria lÃquida Ãrea foliar tuberizaÃÃo high temperature senescÃncia foliar relative growth rate condiÃÃes tropicais growth analysis potato partiÃÃo de matÃria seca temperature anÃlise de crescimento growth cycle earliness chlorophyll melhoramento vegetal stay-green chlorophyll content morphophysiological index

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