Monitoring cotton water status with microtensiometers

Abstract

Stem water potential (Ψₛₜₑₘ) is a key indicator for assessing plant water status, which is crucial in understanding plant health and productivity. However, existing measurement methods for Ψₛₜₑₘ, characterized by destructiveness and intermittency, limit its applicability. Microtensiometers, an emerging plant-based sensor, offer continuous monitoring capabilities and have shown success in certain vine and tree species. In this study, we investigate the efficacy of microtensiometers ability to monitor the Ψₛₜₑₘ of cotton (Gossypium hirsutum L.) under three distinct irrigation treatments in Maricopa, Arizona, an extremely hot, arid environment. We analyze the diurnal dynamics of Ψₛₜₑₘ across the irrigation regimes and compare these measurements with midday leaf water potentials (Ψₗₑₐf) obtained using a dewpoint potentiometer. Our results demonstrate that the microtensiometer-derived Ψₛₜₑₘ closely follows known diurnal patterns of Ψₗₑₐf, tracking with vapor pressure deficit (VPD) and responding to variations in irrigation levels and soil moisture content. Time cross-correlation analysis reveals an 80-minute lag in Ψₛₜₑₘ response to changing VPD under non-water limiting conditions, which shortens under water-limiting conditions. Additionally, we establish a robust linear relationship (R²ₐdⱼ = 0.82) between Ψₛₜₑₘ and Ψₗₑₐf, with this relationship strengthening as water availability decreases. Notably, we observe mean gradients of 1.2 and 0.06 MPa between soil vs. stem and stem vs. leaf water potentials, respectively. Moreover, Ψₛₜₑₘ data proves to be more sensitive in distinguishing between irrigation treatments earlier in the growing season compared to Ψₗₑₐf, leaf temperature and leaf gas exchange parameters. These findings highlight the utility of microtensiometers as valuable tools for monitoring water status in smaller-stemmed row crops such as cotton.

Plant phenotyping relevance

マイクロテンシオメータによる綿の茎水ポテンシャル測定を中心に、既存指標との比較、応答特性、灌漑処理の識別性能を検証しており、植物生理状態のセンシング手法として中心的である。

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