Location: Application Technology ResearchTitle: Photosynthesis, growth, and water use of Hydrangea paniculata ‘Silver Dollar’ using a physiological-based or a substrate physical properties-based irrigation schedule and a biochar substrate amendment
|JAHROMI, NASTARAN - University Of Tennessee|
|FULCHER, AMY - University Of Tennessee|
|WALKER, FORBES - University Of Tennessee|
Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2020
Publication Date: 3/7/2020
Citation: Jahromi, N.B., Fulcher, A., Walker, F., Altland, J.E. 2020. Photosynthesis, growth, and water use of Hydrangea paniculata ‘Silver Dollar’ using a physiological-based or a substrate physical properties-based irrigation schedule and a biochar substrate amendment. Irrigation Science. 38:263-374. https://doi.org/10.1007/s00271-020-00670-7.
Interpretive Summary: Integrating precise irrigation application systems with irrigation scheduling can increase water use efficiency in nursery production. Scheduling irrigation based on measurements derived from the physiological status of the plant can be used as an irrigation-scheduling basis. Another irrigation scheduling technique, particularly suited for low water availability such as during water restrictions, is one in which irrigation is based on substrate moisture availability derived from a moisture characteristic curve. The objective of this research was to evaluate the effect of biochar and two on-demand, need-based irrigation schedules on gas exchange, plant water relations, and biomass gain of container-grown H. paniculata ‘Silver Dollar’ with the goal of reducing water use by exploiting the water buffering capacity while maintaining or shortening production cycles. These on-demand irrigation schedules reduced water use without a negative effect on plant dry weight by maintaining sufficient plant water status and gas exchange. The 10% biochar-amended substrate with a substrate-based irrigation schedule yielded the highest water use efficiency (WUE), making it a promising irrigation scheduling and substrate combination. Biochar also provided a source of K by increasing K concentration in substrate solution and in plant foliage.
Technical Abstract: Developing management practices that make more efcient use of irrigation is important for improving the sustainability of nursery crop production. Integrating refned irrigation scheduling with a substrate amendment like biochar can improve irrigation efciency. The objective of this research was to evaluate the impact of biochar and need-based irrigation scheduling on gas exchange, plant water relations, and biomass gain of container-grown Hydrangea paniculata ‘Silver Dollar’ with the goal of reducing water use and maintaining or shortening production cycles. Containers were flled with pine bark and amended with either 10% or 25% by volume of hardwood biochar. Plants were automatically irrigated by one of the three irrigation schedules. The irrigation schedules were conventional irrigation, delivering 1.8 cm of water in one event each day, and two on-demand, need-based irrigation schedules. The frst was based on the moisture characteristic curve for each of the three substrates developed via the evaporative method. The second was a plant physiology-based irrigation scheduling regime built on the relationship between photosynthesis and substrate moisture content. Scheduling irrigation using a plant physiology or substrate physical properties basis, in combination with biochar, reduced the water requirement for ‘Silver Dollar’ hydrangea without any negative efect on plant dry weight by maintaining sufcient plant water status and gas exchange even just prior to irrigation. Automated irrigation systems coupled with a plant physiology or substrate-based actuation and a water retentive substrate amendment have the potential to reduce nursery crops water use.