Abstract
Lettuce presents an increasing demand, which makes necessary the expansion of the areas destined to its planting. Temperature is a limiting factor, because it acts directly on germination, where changes and adjustments in the hormonal balance, mainly of gibberellin (GA) and abscisic acid (ABA), occur. The objective of this study was to evaluate if the treatment of seeds with gibberellic acid is capable of mitigating the damages caused by high temperatures. The seeds were submitted to germination test, first count, percentage of abnormal seedlings and analysis of shoot and root growth. The treatments consisted of seven concentrations of gibberellic acid (control—not treated with GA, 25 mg L-1, 50 mg L-1, 75 mg L-1, 100 mg L-1, 125 mg L-1, 150 mg L-1) and three constant temperatures (25, 30 and 35 °C). The germination and first count, when submitted at 25 and 30 °C presented an increase up to 50 mg L-1 of GA, while at 35 °C the growth was constant up to 125 mg L-1 of GA. Treatment with GA increased root and shoot length. Giberelic acid mitigated the damage caused to lettuce seeds when subjected to temperatures above the optimum.
Highlights
The lettuce (Lactuca sativa L.) is a temperate, belonging to Asteraceae Family, which consists of the most consumed leaves and has an important role in the diet due to its taste, low cost and nutritional quality, as a source of vitamins, minerals and fiber (Santi et al, 2010)
The experiment was developed in the Laboratory of Seed Analysis of the Agricultural Sciences Center (CCA) of the Federal University of Ceará (UFC), Campus of Pici-Fortaleza, from April to June 2018 using seeds of crisp lettuce “Grand Rapids”
Moinstening was conducted for 16 hours at a constant temperature of 15 °C, until seeds reached 40% water content
Summary
The lettuce (Lactuca sativa L.) is a temperate, belonging to Asteraceae Family, which consists of the most consumed leaves and has an important role in the diet due to its taste, low cost and nutritional quality, as a source of vitamins, minerals and fiber (Santi et al, 2010). When exposed to high temperatures the lettuce seeds may present a temporary inhibition (thermoinhibition) or complete in germination (thermodormity). The reasons of this inhibition are due to the stiffening of the endosperm, which presents itself as the main barrier of impediment to radicular protrusion and embryo growth (Nascimento et al, 2012)
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