Hourly observation and modeling of relationship between dryness of soil and water stress of soybean measured by stomatal conductance at converted field

SAKAGUCHI  Atsushi, TSUJI Takuya, FUJII Toshiki, ARAKI Hideki, TAKAHASHI Tadashi

doi:10.34467/jssoilphysics.149.0_3

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水田転換畑における土壌の乾燥と気孔コンダクタンスを用いたダイズの水ストレスの関係の観測および観測時刻別モデル化
スイデンテンカンバタケニオケルドジョウノカンソウトキコウコンダクタンスオモチイタダイズノミズストレスノカンケイノカンソクオヨビカンソクジコクベツモデルカ

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Abstract

We defined a water stress index which is a ratio of stomatal conductance of soybean between rain fed field and non-water stress field, and regressed the water stress index on soil moisture in the rain fed field. In addition, we applied a Jarvis model of soybean to estimate the stomatal conductance in the non-water stress field without measuring in the field. As a result, the stomatal conductance of both fields did not give significant difference in the morning, and correlation was not seen between the water stress index and the root zone suction in the rain fed field at 10 o'clock. On the other hand, the stomatal conductance gave significant difference in the afternoon, and the higher coefficient of determination was seen between the index and the suction at 13 o'clock when they were regressed by the equations of ellipse, the Feddes model and the S-shape model. We suppose the 13 o'clock would be the suitable time to model the transition of water stress in response to drying of soil. Regarding the Jarvis model, we found that the calibration for each time makes the value of coefficient of determination increase, although this is not reported in previous studies.

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Journal of the Japanese Society of Soil Physics

Journal of the Japanese Society of Soil Physics 149 (0), 3-12, 2021

Japanese Society of Soil Physics

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