Abstract

A.U. Izge and Y. M. Garba

Combining ability studies for yield and yield components of tomato under artificial and deliberate infestation by tomato fruit worm (Helicoverpa zea Boddie) were made over two environments at Lake Alau near Maiduguri (11�?� 6′ N; 13�?� 17′ E) and at Hong (10�?� 15′ N; 13�?� 20′ E) in north eastern Nigeria in a set of 6 lines and 2 testers during the 2009 and 2010 dry season under irrigation. The pooled results showed that both general combining ability (GCA) and specific combining ability (SCA) were influenced by the environment implying that the parents and hybrids must be evaluated over a wide range of environments to have unbiased estimate. The tester Cherry and the lines UC and Roma VF indicated great promise for the production of increased number of fruits per plant and incidentally the fruit yield in tomato under infestation by fruit worm insect. Out of the 12 hybrids studied, 4 each were found to be good specific combiners for number of flower clusters and plant height, and 5 for number of fruits per plant over both the environment combined. Cherry × Hong Large and Cherry × Roma VF were the best specific combiners for number of fruits per plant and incidentally having high number of trichome count. These hybrids could be resistant to this insect. Additive gene action were preponderant for number of flower clusters, number of fruits per plant and days to final harvest, while non – additive action were preponderant for number of leaves per plant, plant heights, weight of fruits and the percentage damaged fruits.