Floral characteristics of heat-tolerant and heat-sensitive tomato (Lycopersicon esculentum Mill.) cultivars at high temperature

The responses of a heat-sensitive (Pusa Ruby) and a heat-tolerant (CL-1131) tomato cultivar to four different temperature regimes were investigated to identify floral characteristics affected by high temperatures. There was an earlier anthesis in cultivar CL-1131 than in Pusa Ruby at 35/30 degrees C (day/night) regime. The flower bud number of the first four trusses and total flower number at 35/30 degrees C were significantly lower than at normal temperature (22/17 degrees C) in Pusa Ruby but not in CL-1131. Stigma exsertion at high temperatures (28/23 degrees C) was the same in both cultivars. Many floral anomalies such as stigma exsertion without anthesis, empty flowers and persistent flowers without fruit-set were also observed in the 35/30 degrees C regime. Antheridial cone splitting was not observed. The use of stigma exsertion and antheridial cone splitting as criteria for selecting against fruit-set as high temperature may be misleading. Therefore, these characteristics alone should not be used for selecting for heat tolerance in tomato. (C) 1998 Elsevier Science B.V.