Optimization of root sampling sites and modeling root length density distribution for wheat and maize

doi:10.3724/SP.J.1258.2013.00036

Abstract

Abstract:

Aims Our objectives were to optimize the positions for root sampling of winter wheat and maize and to simulate the distribution of root length density (RLD) throughout the root zone profile in the North China Plain.
Methods Soil cores were taken at different locations in fields of winter wheat and summer maize at the grain-fill stage, and results were compared to decide the positions for root sampling. The bulk density parameter was used to modify the Gerwitz and Page model to increase the accuracy in simulating the distribution of RLD throughout the soil profile.
Important findings There was a larger spatial difference in RLD in the 0-10 cm soil layer for winter wheat. The difference became smaller below the 10 cm soil layer. For the top 20 cm soil layer, RLD on the row was greater than that between two rows. However, below 20 cm, the situation was reversed, i.e., RLD between two rows was greater than that on the row, indicating the strong proliferation ability of the root system of winter wheat. For maize, RLD sampled at the stem was greater than that sampled 10 cm away from the stem, and much greater than that sampled 20 cm away from the stem for the 0-10 cm soil layer. Below the 10 cm soil layer, RLD was highest sampled 10 cm away from the stem. RLD sampled at the stem around the 30-50 cm soil layer was the lowest among the three positions. The results indicated that in the top soil layer, RLD immediately under the plants was the highest, and RLD decreased with increased distance away from the plant stem. However, with increased soil depth, root proliferation reduced the differences among locations. The high bulk density of soil pan around 10-30 cm significantly influenced the shape of the curve of RLD distribution along the soil profile. Introducing the bulk density parameter into the Gerwitz and Page model significantly reduced the errors of simulated and measured RLD throughout the root zone profile.

Key words: root distribution simulation, root sampling, Triticum aestivum, Zea mays

WANG Yan-Zhe, SHAO Li-Wei, LIU Xiu-Wei, ZHANG Xiao-Yu, ZHANG Xi-Ying. Optimization of root sampling sites and modeling root length density distribution for wheat and maize[J]. Chin J Plant Ecol, 2013, 37(4): 365-372.

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URL: https://www.plant-ecology.com/EN/10.3724/SP.J.1258.2013.00036

https://www.plant-ecology.com/EN/Y2013/V37/I4/365

Figures/Tables 7

Fig. 1 Soil bulk density (0-200 cm) at the two root sampling spots measured after harvesting of summer maize in 2011.

Fig. 2 Root length density (RLD) along the soil profile at different sampling spots under two irrigations conditions for winter wheat.

Fig. 3 Root length density (RLD) along the soil profile at different sampling spots for summer maize at grain-fill stage (n = 4).

Fig. 4 Root length density along soil profile under different treatments at two sampling spots.

Fig. 5 Measured and simulated relative root length density along soil profile at grain-fill stage for winter wheat and summer maize under well-watered condition using a fixed root distribution coefficient δ in sampling spot 1 (A, B) and sampling spot 2 (C, D).

Fig. 6 Measured relative root length density along soil profile at grain-fill stage for winter wheat and summer maize under well-watered condition using a fixed root distribution coefficient (δ = 3) and simulated values with and without bulk density modification in sampling spot 1 (A, B) and sampling spot 2 (C, D).

Fig. 7 The relation of measured relative root length density with simulated values (δ = 3) with and without bulk density modification.

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