Chemical induction of sterility in wheat

Abstract

Foliar application of two spring wheat varieties, Anza and Yecora 70, with RH-531 several days before meiosis in a field experiment almost completely prevented seed development. A single application of 2.0 kg a. i. (active ingredient) of RH-531 per ha with a surfactant gave maximum reduction in fertility. Pollen stainability by acetocarmine was only slightly reduced by RH-531. To reduce fertility to 10% or less, treatment should be made just prior to or at the time of meiosis (jointing stage with flag leaf emerged). The two varieties studied differed greatly in their response to RH-531; however, most of the difference could be attributed to differences in growth stage at the time of treatment. Anza showed increased spike density and thickened floral tissues and was apparently more sensitive to RH-531 than Yecora 70. Even though sterility was induced, the floret response was not typical of a male-sterile wheat and was not favorable to outcrossing. More than 98% of the seeds produced by open-pollination on treated plants were the result of self-pollination as determined by progeny testing. Further experience with RH-531 is necessary to determine whether this compound affects the normal development of male and/or female gametes.