Abstract
A field experiment was performed to explore the compensation effects of different nitrogen (N) regimes on the growth and photosynthetic capacity in different leaf layers of the summer maize hybrid of LuYu9105 under waterlogging at the seedling stage. The results showed that waterlogging significantly decreased the maximum green leaf area (gLA) by 10.0~15.3% and 9.3~22.5%, mainly due to the reduction in the below-ear layer leaves at the silking stage in 2014 and 2015, respectively. Waterlogging also significantly decreased the ear leaf photosynthetic rate (PN), and Fv/Fm, Fv/Fo, ΦPSII and qP at the below-ear layer leaves at the mid- and late-filling stages, which was accompanied by a reduction in the duration of grain-filling (T) by 2.6~5.9%, thus resulting in a loss of grain yield by 7.0~18.5%. Interestingly, a shift in N from basal application to topdressing at the big flare stage was shown to compensate the adverse effects of waterlogging by through increased gLA and leaf photosynthetic capacity at the ear layer and the above-ear layer, as well as a greater grain-filling rate, resulting in an increase in grain yield by 9.9~27.0% and 17.8~25.8% compared to other N treatments. Therefore, this study showed that optimal nitrogen regimes during maize growth are capable of compensating for the impacts caused by waterlogging at the seedling stage.
Highlights
Anhui Province is an important area for food supply in China, and maize is one of the major crops grown in the summer season
Waterlogging reduced the N concentration by 5.1 and 22.1% in the below-ear layer, 2.9 and 12.1% in the ear layer, and 6.7 and 15.3% in the above-ear layer leaves at the silking stage and by 14.4, 9.5, and 6.2% and 14.0 3.2, and 12.8% of the below-ear layer, the ear layer and the above-ear layer leaves at the maturity stage in 2014 and 2015, respectively
Our results showed that with the improvement in the green leaf area (gLA) and N concentration, the photosynthetic capacity was improved at the ear layer leaves in the later filling stage, and the chlorophyll fluorescence parameters photosystem II (PSII) was improved at the ear layer and above-ear layer leaves, indicating that the supplied N could increase the effective quantum yield of photochemical energy conservation in PSII, which is in agreement with previous studies [4, 36, 50]
Summary
Anhui Province is an important area for food supply in China, and maize is one of the major crops grown in the summer season. Summer maize is normally grown on mid-June after winter wheat has been harvested in a summer maize-winter wheat rotation area. When the soil water content of the surface layer exceeds the field carrying capacity by at least 20%, this leads to free standing water on the soil surface [2, 3], and, maize seedling development is often subjected to waterlogging [1, 4].
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