Xác định khả năng kết hợp tính trạng năng suất của một số dòng ngô thuần bằng phương pháp lai đỉnh

Summary Seven inbred lines. viz. VN1, VN2, VN3, VN4, VN5, VN6, VN7 selected by the National Maize Research Institute were topcrossed to two lines, A10 and A20 introduced from India as testers in 2002 spring cropping season. Topcross perogeny was evaluated in autumn-winter season in the same year. The software Topcross 1 was employed to evaluate the combining ability (CA) of the yield traits. The inbred lines VN1 and VN2 had the highest general combining ability, followed by VN7. The tester A20 also had high GCA. The inbred lines VN1; VN2; VN3; VN5 had high SCA with the tester A10, while the lines VN4; VN6; VN7 had high SCA with the tester A20. Based on the combining ability of the yield traits and observations on the morphological characters and field resistance to pests three outstanding combinations were identified, i.e. VN1 x A10; VN4 x A20 and VN6 x A20. These combinations had short growth duration (105-108 days), reasonable plant height (190 cm), good resistance to insect pests and diseases and higher yield than the control LVN-4. These three combinations were recommended for further yield trials in the northern lowland of the country. Keywords: Inbred lines, topcross, general combining ability, specific combining ability