|کد مقاله||کد نشریه||سال انتشار||مقاله انگلیسی||ترجمه فارسی||نسخه تمام متن|
|4927437||1431828||2018||8 صفحه PDF||سفارش دهید||دانلود کنید|
- Soil compaction decreased surface charge of cereal roots.
- Decrease in root surface charge in compacted soil was smaller in maize than other cereals.
- Results of root surface charge help explaining reduced cation uptake from compacted soil.
It is well known, that soil particle surface properties like cation exchange capacity, surface area, and charge density affect ion-exchange reactions in the root zone. However, the exchange processes at the root surface itself also depend on these properties: cation exchange capacity, surface area, which will be determined in this paper for the roots of young wheat, barley, rye, triticale, and maize plants. Undisturbed samples from a Haplic Luvisol developed from loess were taken at 5-10Â cm depth from an “normally compacted” core part of the crop field (Ref.) (bulk density 1.29Â Â±Â 0.06Â MgÂ mâ3) and from a “compacted” (C) (bulk density 1.61Â Â±Â 0.05Â MgÂ mâ3) part in the headland. Plants were grown in these soil cores for 11Â days in a growth chamber. The negative surface charge of the roots and apparent surface dissociation constants were determined based on potentiometric titration in pH between 3 and 10. The surface charges at pHÂ =Â 7 and pHÂ =Â 10 were taken as the root cation exchange capacity (CEC) and total negative surface charge (Qtot), respectively. The differences between the adsorption-desorption data were used to estimate the total apparent surface area (S). The Qtot and S were used to calculate the surface charge density (SCD). Root lengths were determined using WinRHIZO 2007 program. Irrespective of plant species, an increase in the compaction level resulted in an increase in weakly acidic groups and in the total apparent surface area (by 10-25%). On the other hand, strongly acidic groups decreased, as well as the CEC (by 28-45%). Additionally Qtot (by 19-32%), SCD (by 26-46%), root length (by 12-80%), and shoot mass (by 43-81%) all decreased. The increases in S and decreases in the number of strongly acidic groups, CEC, Qtot, and SCD in response to soil compaction were less pronounced in coarse-grained maize than in all remaining small-grained cereals. However, the decreases in root length and shoot mass were the highest in maize. The decline in negative surface charge due to soil compaction is attributed to the cell wall structure deformation and lower production and outflow of the acidic groups from the cell interior and lesser quantity of charged root hairs. These results imply the need to consider the root surface charge properties along with root growth traits while studying nutrient uptake from compacted soil.
Journal: Soil and Tillage Research - Volume 175, January 2018, Pages 226-233