Direct measurement of petiole sap nitrate in potato to determine crop nitrogen status

1993 ◽  
Vol 16 (3) ◽  
pp. 515-521 ◽  
Author(s):  
M. P. Westcott ◽  
C. J. Rosen ◽  
W. P. Inskeep
HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 571b-571 ◽  
Author(s):  
T.K. Hartz ◽  
R.F. Smith ◽  
W.L. Schrader

California vegetable growers are adopting drip irrigation at an accelerating pace, which affords the opportunity for more exacting control of nitrogen nutrition. Consequently, the need for quick, accurate, grower-friendly techniques for monitoring nitrogen status in soil and plant material has increased. Three field monitoring techniques were examined in detail: the analysis of soil water samples drawn by soil solution access tubes (SSAT). leaf reflectance as measured by the Minolta SPAD 502 chlorophyll meter, and petiole sap analysis with a Horiba portable nitrate-selective electrode meter. Nitrate concentration in soil solution was highly stratified in drip-irrigated soils, both with regard to location in the field and position with respect to the drip line, making the use of SSAT technology impractical as a tool for routine N fertigation scheduling. Correlation of SSAT nitrate values to any measure of plant N status was poor. Similarly, leaf reflectance correlated poorly with any measure of tissue N in the crops examined. Nitrate content of petiole sap was highly correlated with conventional laboratory analysis of dry petiole tissue over a range of crops and nitrogen levels.


2021 ◽  
Vol 285 ◽  
pp. 110157
Author(s):  
Alejandra Rodríguez ◽  
M. Teresa Peña-Fleitas ◽  
Francisco M. Padilla ◽  
Marisa Gallardo ◽  
Rodney B. Thompson

1970 ◽  
Vol 13 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Mary Mira

Listening, a significant dimension of the behavior of hearing-impaired children, may be measured directly by recording childrens' responses to obtain audio narrations programmed via a conjugate reinforcement system. Twelve hearing-impaired, school-aged children responded in varying ways to the opportunity to listen. Direct and continuous measurement of listening has relevance for evaluation of remediation methods and for discovery of variables potentially related to listening.


1976 ◽  
Vol 37 (C3) ◽  
pp. C3-127-C3-127 ◽  
Author(s):  
H. HERVET ◽  
S. LAGOMARSINO ◽  
F. RUSTICHELLI ◽  
F. VOLINO

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