Effects of elevated CO2 concentration on growth and water use efficiency of winter wheat under two soil water regimes

Winter wheat (Triticum aestivum L. cv. Kenong9204) was grown in open top chambers with either ambient or elevated CO₂ concentrations (358 ± 19 μmol mol⁻¹ or 712 ± 22 μmol mol⁻¹, respectively) in well-watered or drought conditions. Although elevated CO₂ did not significantly affect the height of the plants at harvest, it significantly increased the aboveground biomass by 10.1% and the root/shoot ratio by 16.0%. Elevated CO₂ also significantly increased the grain yield (GY) by 6.7% when well-watered and by 10.4% when drought stressed. Specifically, in the well-watered condition, this increase was due to a greater number of ears (8.7% more) and kernels (8.6). In the drought condition, it was only due to a greater number of spikes (17.1% more). In addition, elevated CO₂ also significantly increased the water use efficiency (WUE) of the plants by 9.9% when well-watered and by 13.8% under drought conditions, even though the evapotranspiration (ET) of the plants did not change significantly. Elevated CO₂ also significantly increased the root length in the top half of the soil profile by 35.4% when well-watered and by 44.7% under drought conditions. Finally, elevated CO₂ significantly increased the root water uptake by 52.9% when well-watered and by 10.1% under drought conditions. These results suggest that (1) future increases in atmospheric CO₂ concentration may have a significant effect on wheat production in arid and semiarid areas where wheat cultivation requires upland cropping or deficit irrigation; (2) wheat cultivars can be developed to have more tillers and kernels through selective breeding and field management; and (3) fertilizer and water management in topsoil will become increasingly important as atmospheric CO₂ concentration rises.     

Combining cover cropping with deficit irrigation in a Mediterranean low vigor vineyard

The aim of this research was to test the effects of vineyard soil management practices combined with deficit irrigation strategies on the performance of the grapevine (Vitisvinifera L.) red variety Tempranillo. Two soil management practices (soil tillage – ST and permanent resident vegetation – RV) were combined with three deficit irrigation treatments (regulated deficit irrigation – RDI, partial rootzone drying – PRD and conventional sustained deficit irrigation – DI) during two growing cycles. Compared to ST, RV reduced soil water content during spring, inducing a significant reduction in vine vegetative growth, yield and must titratable acidity. The effects of irrigation treatments were not much pronounced. Only in the second season RDI showed a significant reduction on vine vegetative growth, yield and must titratable acidity as compared to PRD and DI whose results were similar to one another.     

A historic account of the invasion of Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) in the continental United States, with remarks on their identification

BACKGROUND: Drosophila suzukii is an oriental species first reported outside Asia from Hawaii in 1980. The first confirmed records for the continental United States were made in 2008 in California. The identification of this pest is difficult because very few published resources exist. RESULTS: It has since been recorded in Oregon, Washington, British Columbia, Alberta, Manitoba, Ontario, Quebec, Utah, Michigan, Wisconsin, Louisiana, North Carolina, South Carolina and Florida. Males are relatively easy to identify by the black apical wing spots and the single row of combs on the first and second tarsal segment of the fore leg. The male genitalia are also very characteristic and will aid in identifying teneral specimens. Females can be identified by the large ovipositor, which is 6–7 times as long as the diameter of the spermatheca. Immature stages can only be identified by molecular techniques. CONCLUSION: Although this species has been recorded from many US states and Canadian provinces, it has not been established in all of these places, and the main economic damage is restricted to the western part of North America. With the characters laid out in this paper, it should be possible to identify the pest with high certainty. Copyright © 2011 Society of Chemical Industry     

华北平原灌溉农田的土壤水量平衡和水分利用效率

华北平原农业面临的主要问题是水资源短缺,地下水位持续下降。通过一维土壤水量平衡模型模拟了华北平原不同灌溉方式下农田耗水量和土壤水分深层渗漏的变化,并分析了作物的产量和水分利用效率。结果显示在正常的灌溉条件下,冬小麦季地下水的采补差额超过了200mm,某生育期一定程度的水分亏缺(返青期、拔节期或灌浆期)能明显减少冬小麦的耗水量,但没有明显减少作物的产量。因此,在一定程度上减少灌溉是可行的,但仍不能达到地下水资源的采补平衡。从长远来看,华北平原维持可持续的地下水灌溉开采,应减少冬小麦的种植面积、增加低耗水经济作物的比例。