Growth and photosynthesis of two genetic materials from coconut palm submitted to artificial defoliation
DOI:
https://doi.org/10.6008/CBPC2179-6858.2020.001.0007Keywords:
Gas Exchange, Leaf Cutters Caterpillar, Growth CompensationAbstract
The Coconut palm seedlings can be attacked by various insect species. especially in the nursery by leaf cutters caterpillars like Opsiphanes invirae, which reduce growth and increase production costs. The objective was to evaluate the effects caused by artificial defoliation, through the morphophysiological parameters in coconut tree seedlings simulated to the attack of O. invirae caterpillars. Two genetic materials were evaluated: Hybrid PB121 and Brazilian green dwarf at four defoliation levels: T0 (control treatment), without defoliation; T30 (30% defoliation); T60 (60% defoliation) and T90 (90% defoliation). Were measured net CO2 assimilation rate (A), stomatal conductance (gs), perspiration rate (E), and intercellular carbon and atmospheric carbon (Ci / Ca), in addition to leaf area, height, stem diameter, dry mass and robustness index. The demonstrated results that seedilings of green dwarf coconut tree in Brazil show higher averages for gs, E and Ci / Ca. The Treatment T90 showed a 17.56% reduction in the rate of net CO2 assimilation (A) compared to T0. On the other hand, the hybrid genetic material PB121 has the largest media for leaf area, height, stem diameter and dry matter of the area. There was no significant interaction between genetic materials and defoliation levels (MGxD). Seedlings of PB121 hybrid with 30% defoliation (T30) were able to recover the lost leaf area, equaling the control treatment (T0). This level of defoliation is equivalent to the consumption of 3 leaf/plants cutters caterpillars, being the biological indicator for control decision making in the nursery.
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