Cultivos de pimentões sob telas fotosseletivas
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2012-05-30
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Universidade Federal de Goiás
Resumo
Sweet pepper is among the ten most important vegetable crops in Brazil, the
production concentrating in the Southeast and Central-West regions, where Goiás State is
the largest producer. Sweet pepper is traditionally cultivates at open field, but protected
cultivation allows for increasing productivity as well as out of season production. Among
the technologies available for shading are the photoselective screens, which attenuate the
solar radiation by way of transmitting better quality incident solar radiation spectra for the
photosynthesis process. Limited research has been developed on this subject in the Goiás
State. A study was proposed, carried out at Goiânia, Goiás State, Brazil (16o35’73”S,
49o16’54”W, 716m), under two objectives: 1) Evaluation of sweet peppers seedling
production under red and blue photoselective screens, a thermo-reflective screen, and a
tunnel plastic greenhouse; 2) Evaluation of the vegetative development and yield of two
sweet pepper cultivars (yellow and red), grown under blue and red photoselective
screenhouses, and at open field. In the first experiment sowing was made in 128-cell trays
filled with commercial growing media, in completely randomized design, with 16 plots per
treatment and 12 seedlings per plot. All data variance were analyzed and compared by the
Scott-Knott test at 5% significance. Solar global radiation (GR), photosynthetically active
radiation (PAR), temperature, and air relative humidity were continuously registered. Data
show that in May and June temperature has greater influence in seedling development than
GR and PAR. The conclusion of the study is that better quality seedlings are obtained in
greenhouses covered with low density polyethylene as compared to those grown under
40% shading blue or red photoselective or thermoreflective screens. In the second
experiment the Eppo (yellow) and Margarita (red) hybrids were grown in 16m x 12m x
2,2m 40% shading screenhouses. The control treatment was open sky beds. For each
cultivar 140 seedlings were planted per environment, making up six independent
populations. Stalk diameter and length and leaves number, area, and mass were measured.
At 120 days from transplanting fruit number, mass, length, and diameter were measured, as
well as the number of fruits lost by sun scald. Data show that photoselective red and blue
screens increased stalk growth and decreased the number of leaves and fruits. No statistical
differences were observed for leaf area, showing that there is compensation between leaf
number and area. Total fruit production per plant decreased from open sky to red screen to
blue screen. However, fruit losses by sun scald reached 35% at open sky and 6% under
screens. Commercial fruit production per plant was higher under red screen, followed by
open sky and blue screen. The conclusion is that, for the red and yellow sweetpeppers and
environments studied, 40% shading red screen results in better plant growth and a small
(4%) increase in commercial fruit production as compared to blue screen and open sky.
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SANTANA, J. Q. Cultivos de pimentões sob telas fotosseletivas. 2012. 61 f. Dissertação (Mestrado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2012.