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Nitrogen, Potassium, and Irrigation Effects on Water Relations of Kentucky Bluegrass Leaves
Author(s) -
Carroll Mark J.,
Petrovic A. Martin
Publication year - 1991
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1991.0011183x003100020045x
Subject(s) - turgor pressure , irrigation , potassium , biology , transpiration , nitrogen , horticulture , poa pratensis , apoplast , agronomy , botany , zoology , poaceae , chemistry , photosynthesis , cell wall , organic chemistry
Transpiration and expansive growth in leaves are turgor‐dependent processes. Solute concentration and osmotic potential are inextricably linked to turgor maintenance. An empirical equation predicting stomatal resistance ( R s ) from bulk leaf turgor (ψ t ) would be useful in developing computer simulations for turfgrass management. A growth‐chambers study was conducted to quantify the relationship between R s and ψ t in Kentucky bluegrass ( Poa pratensis L. cv. A‐34). The effects of N, K, and irrigation frequency on bulk leaf osmotic potential at full turgor (ψ π100 ) and apoplastic water fraction (AWF) also were examined, using psychrometric techniques. Treatments consisted of two rates of N and K and two irrigation frequencies. An exponential model was used to describe the relationship between R s and ψ t . The least squares prediction equation was R s = 581 + 2500 exp(−6,99ψ t ), r 2 = 0.69, where ψ t and R s . are expressed in units of MPa and s m −1 , respectively. Increasing the time between rewatering containers to −0.02 MPa from 1 to 5 d did not influence ψ π100 . For plants watered dally, increasing the amount of N supplied every 30 d from 35 to 175 kg ha −1 increased ψ π100 0.22 MPa, while increasing K from 17.5 to 175 kg ha −1 for the same application interval caused ψ π100 to decline 0.20 MPa. Altering the supply of N or K did not affect ψ π100 when the containers were watered every 5 d. Increasing the irrigation interval from 1 to 5 d caused AWF to decline from 22 to 12%; however, AWF estimates were highly variable. Results indicate the combined influences of N and K fertility practices can have a significant impact on the concentration of osmotically active solutes within Kentucky bluegrass bulk leaf tissue.