Summary: | During the agricultural cycles of 2011/2012 and 2012/2013, the transmitted sunlight by six nets with 30%
shade: aluminized, gray, pearl, blue, red (colored) and black, and its effects on growth, development
and yield of cucumber were evaluated. The red net transmitted 42.6, 23.7, 40.3, 52.9 and 57.3% of sun especlight
(350-1050 nm), photosynthetic active radiation (400 to 700 nm), red light (600-700 nm), far red
light (700-800 nm) and infrared radiation (800-1050 nm); the gray net transmitted 83.5% more ultraviolet-
A light (350-400 nm) and the blue net 36% more blue light (400-500 nm), that the respective black
net transmissions. The nets did not significantly change the air temperature, but colored nets increased
the maximum relative humidity (3.4 to 4.2%), temperature of the upper leaf (0.2 to 0.9 °C) and the photosynthetic
leaf responses: transpiration, stomatal conductance and CO2 assimilation. Consequently, the
plant height (240.0 cm), stem diameter (10.0 mm), leaves number (22.2), leaf area (406.0 cm2 per leave),
greenness (41.6 SPAD units), stem and leaf dry weight (52.5 and 14.7 g per plant, respectively) of plants
growing in black net, were increased by 11.6, 10, 12.6, 23.4, 22.8, 9.5 and 36.7% with the red net. The
pearl, red, aluminized and blue nets showed to be viable options because they increased plant yield
compared with conventional black net (5.2 kg m-2) with raises of 71.1, 48.1, 46.1 and 46.1%, respectively. |