Abstract
The water relations of pepper plants (Capsicum frutescens L.) under conditions conducive to guttation were studied to evaluate the control of plant water stress with polyethylene glycols. The addition of polyethylene glycol 6000 to the nutrient solution resulted in water relations similar to those expected in soil at the same water potentials. Specifically, xylem pressure potential in the root and leaf became more negative during a 24-hour treatment period, while osmotic potential of the root xylem sap remained constant. The decrease in pressure potential was closely correlated with the decrease in osmotic potential of the nutrient solution. In contrast, the addition of polyethylene glycol 400 to the nutrient medium resulted in a reduction of osmotic potential in the root xylem sap; this osmotic adjustment in the xylem was large enough to establish an osmotic gradient for entry of water and cause guttation at a nutrient solution osmotic potential of −4.8 bars. Pressure potential in the root and leaf xylem became negative only at nutrient solution osmotic potentials lower than −4.8 bars. About half of the xylem osmotic adjustment in the presence of polyethylene glycol 400 was caused by increased accumulation of K+, Na+, Ca2+, and Mg2+ in the root xylem. These studies indicate that larger polyethylene glycol molecules such as polyethylene glycol 6000 are more useful for simulating soil water stress than smaller molecules such as polyethylene glycol 400.
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Selected References
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- Barrs H. D. Root pressure and leaf water potential. Science. 1966 May 27;152(3726):1266–1268. doi: 10.1126/science.152.3726.1266. [DOI] [PubMed] [Google Scholar]
- Kaufmann M. R. Water relations of pine seedlings in relation to root and shoot growth. Plant Physiol. 1968 Feb;43(2):281–288. doi: 10.1104/pp.43.2.281. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Klepper B., Kaufmann M. R. Removal of salt from xylem sap by leaves and stems of guttating plants. Plant Physiol. 1966 Dec;41(10):1743–1747. doi: 10.1104/pp.41.10.1743. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Michel B. E. Carbowax 6000 compared with mannitol as a suppressant of cucumber hypocotyl elongation. Plant Physiol. 1970 Apr;45(4):507–509. doi: 10.1104/pp.45.4.507. [DOI] [PMC free article] [PubMed] [Google Scholar]