Effects of Hydrogels on Tree Seedling Performance in Temperate Soils before and after Water Stress

Abstract

Super Absorbent Polyacrylate (SAP) hydrogels absorb and store water thereby aiding plant establishment when incurporated in the soil. The effect of cross-linked SAP hydrogel amendment on the performance of tree seedlings of Picea abies, Pinus sylivestris and Fagus sylvatica grown in temperate soils under water stress and non-water stress periods was investigated in a green house. The objective was to compare the root and shoot biomass of seedlings of the three species grown in sand, loam and clay soils amended with 0.4% w/w hydrogel in non water stress conditions as well as survival, root and shoot biomass after subjection to water stress. The seedlings were grown for 16 weeks, harvested and shoot as well as root biomass determined before water stress. The seedlings were also subjected to water stress and their biomass assessed at death following the water stress. The results showed that root and shoot biomass were generally higher in hydrogel amended soils compared to the controls. Root and shoot biomass of Fagus sylvatica was lower compared to Picea abies and Pinus sylivestris before water stress. The 0.4% hydrogel amendment significantly increased species' survival in the different soils studied. Although root biomass was higher in hydrogel amended sandy soil compared to other soils, P. sylivestris and F. sylvatica shoot biomass were higher in hydrogel amended clay and loam soils compared to the sandy soil after water stress. Biomass was higher in sand compared to loam and clay soils under non-water and water stressed conditions. Since SAP hydrogel amendment improved the survival and biomass production of tree seedlings before and after water stress, use of SAPs could be promoted to enhance seedling production in water stress and non-water stress environments.

Reduction in Water Stress for Tree Saplings Using Hydrogels in Soil

“…However, the concentration of hydrogel was positively correlated with SPAD readings (chlorophyll content) in the maples (hydrogel = 1%, r = 0.62, p < 0.01, Figure 3(b)). The different responses of the two tree species are consistent with their coping strategies in the face of water stress [18] [43]. In general, silver maples grow in wet, poorly drained soils as in floodplains or stream banks [44] [45].…”

“…Hydrogels are hydrophilic and contain carboxylic groups, enabling them to bind cations and adsorb water [17]. The water and nutrients stored in hydrogels are released gradually for plant growth under water limiting conditions, whereas under non-water limiting conditions, they are reported to enhance nutrient uptake for plant growth [18]. This is of special interest for urban foresters, because water stress and nutrient deficiency are two important growth-limiting factors for street trees.…”

Super absorbent polymer application in seeds and planting furrow: it will be a new opportunity for rainfed agriculture

“…This effect was also found by Pazderu and Koudela (2013), who compared the effect In both Experiment 1 (Table 4) and Experiment 2 (Table 5), fewer plants were observed when SAP was applied to the seed. This effect was also found by Pazderu and Koudela (2013), who compared the effect of the use of SAP application as a solution (at three levels of concentration) on the germination of vegetable seeds. The authors attributed this effect to the fact that SAP can reduce the speed of water absorption of seeds, resulting in slower germination.…”

“…Approximately 96% of this production is not irrigated and depend only on the rainfalls (PAULINO et al, 2011). In addition, in the main grain-producing regions, two crops are common: one in the spring/summer (receiving greater precipitation), and the other in autumn/winter (receiving less precipitation) when production is more affected by low water conditions.…”

“…Therefore, novel technologies that optimize water use efficiency at the seedling development phase of rainfed crops are needed. In the forestry sector, SAP has been used to minimize water stress in the planting of eucalyptus and Pinus seedlings (ORIKIRIZA et al, 2013). Moreover, in Brazil, SAP is widely used in winter plantings to reduce seedling mortality and the frequency of glue irrigations.…”