Search Results (2)

Chinese pistache tree (Pistacia chinensis Bunge, Anacardiaceae) is an important oil, ornamental and afforestation tree species. Seeds of this species are known due to their erratic germination, so it is urgent to determine the causes of such dormancy. To do so, we tested water permeability, respiration rate, mechanical constraint and germination inhibitors. The results indicated that the testa was water-permeable, the raphe and hilum as the areas that contributed most to imbibition. Removal of the testa increased the imbibition rate and improved the oxygen availability to the embryo. Furthermore, the analysis of the extracts showed that the endotesta and embryo may contain inhibitors that negatively affect germination and seedling growth. The widely targeted metabolomics revealed that phenolic acids and organic acids may be the potential inhibitors. Seed scarification, exogenous gibberellin (GA₃) and cold stratification greatly increased the germination, but seed scarification (removal of the exotesta and 1/2 cotyledon) was the most effective strategy, since it increased the germination up to 89% after 5 days of incubation, a rate significantly higher regarding the other strategies, which barely reached 60% in 20 days. In conclusion, there seems to exist both a mechanical dormancy due to the testa and a physiological inhibition due to the embryo. Full article

With increased interest in water conservation, traditional residential landscapes, which often include turfgrass and other high-water use plants, are often eliminated in favor of low water use desert landscape plants. But even with a desert landscape, home owners often overwater, thereby reducing any water conservation possibility. This experiment was designed to demonstrate that plants can retain physiological health even when on reduced irrigation. Three 26.8-m² plots each of two contrasting landscapes, designated as either traditional or desert, were installed in a desert environment using a pot-in-pot in-ground system. Plots were irrigated at 100% or 50% of evapotranspiration (ET) with either sprinklers (turf) or drip emitters (trees and shrubs) using a modified crossover design. Midday stem water potentials (Ψ_md) for Arizona ash, Indian hawthorn and Cleveland sage exhibited seasonal differences. In Chinese pistache, Ψ_md remained stable when irrigation treatments were lowered from late spring/early summer (−0.26 MPa) to late summer (−0.35 MPa). Chinese pistache maintained less negative osmotic potential when irrigation increased from 50% ET (−5.13 MPa) to 100% ET (−3.68 MPa) in early fall. The ability of Chinese pistache to maintain Ψ_md and osmotic potential may indicate this species’ resilience to drought. Surprisingly, Arizona ash sustained greater relative water content in late fall when irrigated at 50% ET (92% elative water content (RWC)) than when irrigated at 100% ET (76% RWC) and this might be due to osmotic adjustment. The plants used in this study recovered after two weeks of full (100% ET) irrigation suggesting that landscape managers could irrigate at 50% ET for a limited period (approx. four weeks) as a way to conserve water. Full article