Effect of hydropriming and acclimation treatments on Quercus rugosa acorns and seedlings

Abstract

To facilitate restoration of the lava field forests surrounding Mexico City, we developed methods to improve the germination and field seedling performance of Quercus rugosa using hydropriming (regulated hydration of seeds in water), and we used special watering regimes to improve seedling acclimation. The size, dry mass, fresh mass and water content of seeds were measured, and curves were generated to evaluate acorn hydration and dehydration. The effects of stratification (5°C), heat shock (50°C) and scarification on germination were tested. All treated seeds and controls were germinated in control chambers at 21°C. One hydropriming cycle (PC) consisted of two hydration days followed by two dehydration days; treatments of 1, 2 and 3 PCs were tested. Seedlings from 1PC to 2PC were acclimated in a shade house under high and low watering regimes (400 and 200 mL week -1 , respectively). In the shade house and field, the effects of hydropriming and watering treatments were evaluated by measuring length, basal diameter, crown cover, number of leaves and branches and leaf area of seedlings. Dry and fresh mass were used to calculate acorn water content. Dehydration and hydration curves displayed hysteresis. Acorns exhibited physiological dormancy, which could be overcome by stratification or by 1 month of storage. 1PC led to increased germination rates and final germination. In both the shade house and field, 1PC showed a positive effect on all seedling growth parameters except branch number. Field survival was not affected. Generally, 1PC favoured efficient seed germination, seedling vigour and homogenous plant production.

Técnicas para superação da dormência de sementes de guanandi

“…Limas et al (2007) observaram o mesmo comportamento em sementes de ucuúba, espécie recalcitrante, que ganhou menos de 5% de água após 72 horas de hidratação. O incremento de umidade também foi pequeno para sementes recalcitrantes de Quercus rugosa: apenas 8,2% após 400 horas de hidratação (Castro-Colina et al, 2012). Entretanto, espécies ortodoxas tendem a uma expressiva absorção de água após a embebição, como constatado em pinhão-manso (Jatropha curcas), cujas sementes absorvem mais de cinco vezes a quantidade inicial água (7,5%) em 24 horas de embebição, e alcançam o teor de 43% (Braga et al, 2012).…”

Effects of seed priming on germination and seedling growth of desiccation-sensitive seeds from Mexican tropical rainforest

“…An exception is Quercus rugosa, which inhabits highly disturbed and stressful lava fields located in the southern hills of Mexico City. Sensitivity to desiccation in acorns of Q. rugosa limits their regeneration in its habitat, but hydropriming has been shown to improve the germination and to increase the seedling growth in the field (Castro-Colina et al 2012).…”

Effects of hydropriming treatments on the invigoration of aged Dodonaea viscosa seeds and water‐holding polymer on the improvement of seedling growth in a lava field

“…Only a few studies have been conducted in trees from other ecosystems, including Callitris spp. (Adams ), Wigandia urens (González‐Zertuche et al ), Cecropia schreberiana (Sánchez et al ), Mimosa bimucronata , Guazuma ulmifolia (Brancalion et al , , respectively), Parkia multijuga (Calvi et al ), Albizia julibrissin (Sedghi et al ), Quercus rugosa (Castro‐Colina et al ), Aegle marmelos (Venudevan & Srimathi ), and Gmelina arborea (Moruf et al ), among others.…”