Scientia Horticulturae, 28 (1986) 299--300 299 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

Book R e n e w

PLANT ENVIRONMENTAL MEASUREMENT

Plant Environmental Measurement by Joe J. Hanan. Bookmakers Guild, Longmont , CO, 1984, 352 pp., price $60.00, ISBN 0-917665-00-7.

This t ex tbook on the wide scope of plant environmental measurement deals with both the basic principles of environmental physics, measuring techniques and instrumentation, and with sensors and instruments devel- oped in this field of interest up until about 1980. The book, writ ten as a guide for the practical horticulturist, plant breeder, biologist, etc., enables one to select and exploit sensors and instruments that measure the physical plant environment as part of plant-oriented research.

In Chapter 1, the physical plant environment is introduced concisely, followed by a solid explanation of significant figures and errors as well as a description of the internationally accepted International System of Units (SI-system). However, this convention is not used consistently throughout the book (even in the sections dealing with principles one finds degrees F, inches of mercury, dyne cm -2, etc., together with SI-units). Another minor remark in this respect is that throughout the book the unit of temperature in the SI-system printed as °K instead of K, even though this was correctly in- t roduced in Chapter 1. One would normally expect a demonstrat ion of the proper use of the internationally accepted units in new textbooks.

Chapter 2 gives a very thorough introduction to the principles of signal conditioning and noise control. This chapter explains clearly how the prob- lems, due to the connect ion between sensors and measuring instruments, can be solved. Such knowledge is indispensible for everyone working with sensors and instruments, both in the laboratory and in the field. The fol- lowing chapters deal with the measurement of temperature, radiation, humidity, gas concentration and wind velocity in turn. Each chapter begins with an outline of the basic principles, followed by a survey of measuring methods, sensors and instruments. Of course such a survey is limited as it is restricted to the period determined by the closing date for manuscript completion. However, it illustrates the basic principles very adequately. In such a manner, the reader is quickly introduced into the field of interest. In the best reviews, the emphasis ought to be given to basic principles; the author has stressed this by reviewing sensors and instruments which even include electronic circuitry which is 10--20 years old.

In Chapter 3 on temperature measurement, the classical temperature sensors are thoroughly discussed. The relationship for radiative transfer (eqn. 3.11) in this chapter is reproduced erroneously. The accuracy of infrared thermomet ry is underestimated, as in the illustrating example, the body (vegetation) radiates to an atmosphere at 0 K. This is very un-

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realistic, since a very low sky temperature differs only about 25 K from the canopy temperature. This is compensated in Chapter 4 on radiation, where radiative transfer is indeed reproduced correctly. The section on radiometric and photometric radiation in this chapter are an impetus for everyone involved in environmental measurements. The comment that . . . . " if plant investigators continue to use the improper terminology (photometric terms) the result will continue to be garbage" especially deserves wide attention. The measuring instruments for radiation are introduced correctly, although some additional remarks could have been made on more specialised items.

Concluding, it can be stated that this book presents a very good intro- duction into the field of environmental measurement, but it has to be used as a supplement to other existing textbooks in this field. The book cannot substitute for a literature study because recent literature is not included. However, the book does include a lot of numerical data, both in the text and in clearly organised appendices, which certainly increase its practical usefulness.

G.P.A. BOT Department of Physics and Meteorology

Agricultural University Wageningen

The Netherlands