Evaluation of Seven Tetrazolium Salts as Vital Pollen Stains in Cotton Gossypium hirsutum L . 1

CYTOGENETIC studies involving translocations are aided by a simple technique of differentiating normal and semisterile or sterile plants. Routine cytological studies, though very conclusive, are time consuming and only a limited population of plants can be handled. In corn and some other crops it is easy to distinguish between normal and semisterile plants by the use of nonvital pollen stains but in cotton, pollen viability is not reliably estimated by the use of iodine or other nonvital stains. Tetrazolium salts offered a promise of success since their utility in seed germination tests in several crops had been demonstrated. Sarvella and Johnson (6) reported the success of two tetrazolium salts as vital stains for cotton pollen but these findings were not supported by the results of Tiranti. Therefore, the present study was undertaken to evaluate several tetrazolium salts at differing concentrations and for differing periods of staining in an attempt to find a suitable vital stain that would give a reliable measure of pollen viability in cotton. The development of 2,3,5-triphenyl tetrazolium chloride (TTC) and its application to biology has been reviewed by Smith (7) and by Roberts (5). The basis of the reaction is reduction of the soluble colorless triphenyl tetrazolium salt to the insoluble red formazan, which in turn gives red or deep purple color in living tissues. Viability is measured in terms of reducing activity or red coloration. Mattson et al. (3) reported the potentialities of tetrazolium salts as a test reagent for living materials such as the fleshy parts of apples, oranges, and grapes, the gills of mushrooms, carrot roots, and stigmas and ovaries of certain pollinated flowers. Vietez (8) reported that a 2% TTC solution at 50° C. provided a quick and reliable