Respostas ecofisiológicas de pimenta longa (piper hispidinervum c.dc.) submetida a diferentes condições de manejo no município de Igarapé-Açu, PA.

Abstract

Aiming to address appropriate management in the cultivation, it was studied, between May/98 and March/99, in field conditions, in the Municipal district of Igarapé-Açu, PA, the water relations, the biochemical responses, biomass production and allocation, and essential oil production in plants of pimenta longa cultivated with and without irrigation. The treatments were: T1 - irrigated and nonfertilized; T2 - irrigated and fertilized; T3 - non-irrigated and non-fertilized; T4 - non-irrigated and fertilized. Starting from the 6" day without the rainfall, alterations were observed on the biophysical variables. In the 15" day of water stress, in the treatments without irrigation, it was observed the largest impact on the variables, where the pre-dawn water potential was reduced from -0.05 MPa to -0,5 MPa, the stomatal resistance increased from approximately 0.3 s.cm” to more than 5.0 s.cm'', at 9:00h a.m, and net photosynthesis was reduced from 20 umol.m?.s", to values around 1.4 umol.m?.s*. After the periods of defiícits, the plants showed recovery capacity, displaying values close to the ones observed in the plants without water stress. lt was observed that in the driest months, there was a reduction in the chlorophyll content, independent of the treatment, being chlorophyll a, more affected. Water stress reduced the contents of total soluble sugars and of potassium, while the protein and phosphorus contents stayed practically constant, during the observation period. In the irrigated plants, potassium contents increased with plants age. Water deficiency affected dry mass production of all plant parts, and it also reduced the number of plants in approximately 30%. Biomass and essential oil productions were reduced by 50%, compared to the irrigated treatments, until the 7" month after planting, when changes in the biomass allocation pattern were noticed in the irrigated treatments. In the 9"" month, with the re-establishment of the rainfall, recovery of plant growth was observed in the non-irrigated treatment. Thus, water deficiency in any phase of the plant development, affects the production of essential oil.