Studies on Heterosis of Chili (Capsicum annuum L.)

Abstract

Ten varieties of local chili were collected from different locations in Thailand. Observation and evaluation of those varieties were made in comparison with five male sterile varieties introduced from abroad. Five varieties were selected among these ten varieties as male parents. They were self-pollinated for two generations before crossing with two male sterile lines. Ten F1 hybrid lines were obtained and compared with the male parents at a private company in Chiang Rai and at the Department of Horticulture, Chiang Mai University. The results showed that the three F1 hybrid lines, K Y1-1 x Bang-Chang, KY 1-1 x Nhum Khiew and KY 1-1 x Nhum Khiew Maejo yielded 76.96%, 39.13% and 8.09% higher than the male parents which are landrace varieties. Moreover, the fruit quality was also higher than those of the male parents. They also have a rather good shape, smooth skin and big fruits. The degree of pungency as measured by spectrophotometer was different from that measured by human bite test. The highest pungency of bite test was found in Fang chili whereas the spectrophotometer methods indicated that Bang-Chang chili had the highest pungency. KY 1-1 x Nhum Khiew Maejo, CF21789 x Nhum Khiew and KY 1-1 x Nhum Khiew showed high percentage of heterosis. Pungency of F1 hybrid tested by spectrophotometer methods indicated that different male parents produce different degree of pungency. Pungency was segregated between their male and female parents, revealing that the trait was polygenically controlled with mainly dominant gene action. Variation in degree of pungency was also controlled by environment.