New Weighing Method to Measure Shoot Water Interception

The need exists to develop a method that can quantitatively measure water interception from plant shoots. This paper describes a new method for measuring canopy water interception. Corn (Zea Mays L.) was grown in $13\mathrm{L}$ buckets containing Valentine fine sand (Mixed, mesic Typic Ustipsamment) under a climate-controlled growth chamber. Plants were taken out of the growth chamber for $2–3\mathrm{h}$ periods for measurements of shoot water interception in a hydraulic laboratory equipped with an Accupulse system suspended from the ceiling that was used to wet the corn shoots at growth stages V7–V13. A lightweight, movable framework was placed around a balance, and buckets containing corn plants were placed on the scale one container at a time. Water was applied until all shoot surfaces were wet and runoff from the leaves and stalk surfaces could be observed. The weighing method for shoot water interception was tested by using the balance to instantaneously measure shoot water interception during application of water and after plant surface runoff ceased. The balance, bucket, and soil surface were covered with plastic to protect them from water, so only the shoots were wet. Interception by the shoot of corn ranged from $31\text{to}47\mathrm{mL}{\text{shoot}}^{-1}$ . These values were much smaller than previous values reported in the literature. The average coefficient of variation was 9.2% for two studies, which was much lower than previously accepted methods. This study suggests that the weighing method for shoot water interception can be used to quantitatively and more accurately measure water intercepted by corn shoots. The weighing intercepted method values presented in this paper are low and suggest that previous interception methods overestimated the interception values.