Effects of high temperature treatments on seed yield and self incompatibility in chrysanthemum

Treatment of plants of 3 self-incompatible chrysanthemum clones for 12, 24 and 48 h periods at 30, 35 and 40 °C greatly influenced self- and cross-seed yield as compared to a control held continuously at 16 °C N and 21 °C D. Seed yield following cross pollination was generally not significantly different from the cross control when plants were treated at 30 and 35 °C but nearly always was adversely influenced by 40 °C regardless of the treatment length. In 4 treatments selfed-seed yield on clone 67-111-42 approached or slightly exceeded 50% of that of a high yielding corresponding cross pollination. Selfed-seed on the other 2 clones did not, however, exhibit a similar response. Three of 14 clones which were either sibs of 64-111-42 or derived from matings between 67-111-42 and its sibs and selfed progeny were classified as self compatible when heat treated at 35 °C for 24 h. Plants of 4 progenies from reciprocal crosses between a heat sensitive clone and two heat insensitive clones were similarly evaluated and 14 out of 112 plants were classified as self compatible.