Irrigation control of cowpea plants using the measurement of leaf thickness under greenhouse conditions
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In this study, the thickness of cowpea leaves was measured with high data- and time-resolution, and the dynamics of leaf thickness was subsequently used as an input parameter for automated irrigation control at the greenhouse level. Under non-stressful environmental conditions, leaf thickness showed only minor diurnal and almost no nocturnal fluctuations. In an extreme water deficit stress scenario, leaf thickness decreased dramatically by as much as 45% within a short period of time. In a more realistic situation, leaf thickness was kept fairly constant for several days, but decreased substantially when water deficit stress became too severe for the plants to cope with any longer. This characteristic collapse of leaf thickness was used as an input parameter for the automated initiation of irrigation. Upon automated irrigation, plants re-established their nominal leaf thickness quickly and kept this leaf thickness constant for several days, until signaling the need for the next irrigation by a subsequent decrease of leaf thickness. By using the measurement of leaf thickness for irrigation control, between 25 and 45% of irrigation water could be conserved compared with a typical timed irrigation schedule.
KeywordsLeaf Thickness Water Deficit Stress Irrigation Event Daily Fluctuation Irrigation Control
This study was supported by the National Science Foundation, award-number 0712605. We also would like to thank Tom Lemieux of the University of Colorado’s greenhouse for his advice, Dr. Ken Knutson of the College of Agricultural Sciences at Colorado State University for his review comments, and the anonymous journal-reviewers for their comments.
- Bachmann F (1922) Studien über die Dickenänderung von Laubblättern. Jahrb wiss Bot 61:372–429Google Scholar
- Carpenter SB, Smith ND (1979) Variations in shade leaf thickness among urban trees growing in metropolitan Lexington, Kentucky. Castanea 44:94–98Google Scholar
- Chaney WR (1970) A device for the continuous monitoring of changes in leaf thickness. Forest Sci 16:56Google Scholar
- Esau K (1977) Anatomy of seed plants. Wiley, New YorkGoogle Scholar
- Gausman HW (1974) Leaf reflectance of near-infrared. Photogramm Eng 40:183–191Google Scholar
- Sharon Y, Bravdo B-A (1996) Irrigation control for citrus according to the diurnal cycling of leaf thickness. Proceedings of the international conference on water & irrigation, Tel Aviv, Israel, pp 273–283Google Scholar
- Sinclair TR (1968) Pathway of solar radiation through leaves. M.S. thesis, Purdue University, Lafayette, INGoogle Scholar
- Taiz L, Zeiger E (eds) (2006) Plant physiology, 4th edn. Sinauer Associates, SunderlandGoogle Scholar