Preparation techniques and student evaluation of bioplastic specimen blocks for use in crop science teaching

Abstract

Plastic specimen blocks enhance crop science lecture and laboratory teaching according to student reaction measured three semesters in the Department of Agronomy, University of Illinois. Students indicated that these visual aids are useful, interesting, important, and successful in promoting teaching objectives. Similar positive student responses to the use of plastic-embedded crop specimens were found among all classes and majors enrolled in the introductory crop science course. Agronomic specimens which have been successfully embedded include: seeds of weeds and crops, grass collars, flowers and typical leaves of plants, grass spikelets, plant inflorescences, ears and ear sections of corn, soybean pods, and nodulated soybean roots. Special “freeze dry” techniques are essential in preparing wet plant specimens for embedding since plastic resin does not mix with water. Advantages of preserving agronomic specimens in bioplastic blocks include: (a) minimum breakage because of fragile nature of dry specimens (b) easy stereomicroscopic examination, and (c) preservation of plant materials in natural color for repeated use.