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摘要
Studies on N(2) fixation by grain legumes during periods of winter waterlogging prone Mediterranean regions have rarely been performed across scales. Here, we quantified the spatial variability of N(2) fixation by rain-fed chickpea (Cicer arietinum L.) at the field- and micro-scales (0.15 m spacing) after waterlogging during the vegetative growth phase in the winter. We also determined effects of tillage (standard and minimum) and crop and soil variables on N(2) fixation in water stressed conditions. After waterlogging, yield was greatly reduced but there were no visible signs of water stress or tillage effects on N(2) fixation. At the field scale, percent N derived from N(2) fixation (%Ndfa) ranged from 51 to 93 % and was related to the amount of soil-derived N in the plant. Total grain N did not increase when N(2) fixation increased and the amount of N derived from the soil was replaced with fixed N. In contrast, %Ndfa at the micro-scale, ranging between 0 to 72 %, was primarily related to yield and total plant N whereas available soil N or any of the other measured soil properties were not significant predictors of %Ndfa. Total N in the grain increased solely due to N(2) fixation as the contribution from soil N remained constant. Although %Ndfa had a nearly pure nugget variance across the scales, total N derived from N(2) fixation (gNdfa) showed a relatively high level of spatial correlation. The range of available soil N pools was likely different at the two scales, leading to differences in the responses of chickpea N(2) fixation to available soil N.
- 出版日期2011-4
