Monitoring Plant Water Status With Plant-Air Temperature Difference In Rice

As the core technology of modern agricultural production, quick non-destructive monitoring crop water status is of great significant for crop precision irrigation and saving water resource. In this study, a series of pool cultivation experiments with different rice varieties and soil water treatments were carried out in different years. The growth and development characteristics of rice were analyzed, the quantitative relationship of leaf-air temperature difference to leaf water status rice was confirmed, the model for monitoring plant water status was developed based on canopy-air temperature difference. These results provide a technical and theoretical basis for non-destructive monitoring crop status and intelligent diagnoses.The growth characteristics, yield and water productivity of rice under different soil water treatmentswere studied. The results showed the height, indernodes length, panicle length, the primary and secondary branches were affected by soil water content, the treads were W4>W3>W2>W1. In initial growth stage, all water treatments of varieties, SPAD order in different leaf position from high to low was L3>L2>L1; as initial filling stage, SPAD of first leaf was higher than any other leafs. The maximum of stomatalconductance, transpiration and photosynthesis was in the low water stress treatment. In initial filling stage, the index of photosynthesis order in different leaf position was L1>L2>L3, it had no clear order in other stages. It also had a significant direct ratio between upper dry matter and soil water treatments, significance of differences between the means of the treatments gradually increasing as the growth process of rice.The yield of Wuxiangjingl4in treatment W1, W2was61.14%and29.13%lower compared with the reference treatment, but which in W3was0.96%higher, while Liangyoupeijiu was64.11%,28.76%lower, and2.08%higher respectively.The water productivity of Wuxiangjing14was10.69%lower but1.53%and21.15%higher than that under continuous flooding irrigation treatment, while Liangyoupeijiu was16.39%lower but2.46%and22.13%higher respectively. The study result provides a technical support for precise management of rice water and saving water production.The dynamic characteristics of rice leaf water content and leaf-air temperature difference under four soil water treatments were investigated, the relationships of stomatal conductance, transpiration rate, leaf water content with leaf-air temperature difference were analyzed. Results showed the values of leaf water content in the same leaf position and soil water treatments were W1<W2<W3<W4, but a negative correlation relationship between leaf-air temperature difference and soil water treatment, the values of leaf-air temperature difference were gradually increasing from transplating to maturity stage. In all development stages, stomatal conductance, transpiration rate and leaf water content with leaf-air temperature difference showed negative relativity, giving the determination coefficient of over0.50.The dynamic characteristics of plant water content, total leaf water content, leaf area index, Canopy-Air Temperature Difference (CATD) under60°and90°measuring angles were determined. The main influence factors of CATD and the relationships of plant water content, total leaf water content with CATD were analyzed. The distribution of plant and total leaf water content of rice were W1<W2<W3<W4, the leaf area index was the highest under low-grade soil dry stress (W3) of Wuxiangjingl4and water flooding irrigation (W4) of Liangyoupeijiu in heading stage. The influence factors of CATD included air temperature, relative humidity, light intensity and leaf area index, air temperature with CATD showed negative relativity. The value of CATD was gradually increasing from transplanting to maturity stage, the plant water content, total leaf water content and CATD of2measuring angles showed naegative relativity, giving the determination coefficient of over0.60. It showed the value of CATD could use in the real-time monitoring of plant water condition of rice.