HETEROSIS AND COMBINING ABILITY ANALYSIS IN Brassica rapa L.

Abstract

Field experiment on rapeseed (Brassica rapa L.) involving 7 x 7 full diallel cross including reciprocal were conducted at the Sher-e-Bangla Agricultural University, Dhaka during the winter season of 2018-2019. Heterosis and Combining ability were estimated for seed yield and other related characters such as plant height, days to 50% flowering, days to maturity, no. of primary branches per plant, no. of siliqua per plant, no. of seeds per siliqua, length of siliqua and hundred seed weight per plant. Out of forty-one crosses, the hybrid SAU proposed 4 ×BARI Sar-15 was found to be the best for number of primary branches per plant. While the cross BARI Sar-6 × Local Tori-7 produced maximum number of secondary branches per plant. The cross BARI Sar-6 × Local Tori-7 produced maximum number of siliqua per plant. maximum length of siliqua was found in SAU proposed 4 × BARI Sar-6 whereas BARI Sar-17×BARI Sar-14 produced the highest number of seeds per siliqua. The highest seed yield was also observed in the hybrid Local Tori-7×Yellow Special. Highly significant positive heterosis was found in the cross SAU proposed 4 × BARI Sar-17 over better parent and in SAU proposed 4 ×BARI Sar-15 over mid parent for plant height. The hybrid SAU proposed 4 ×Yellow Special was found to have the best heterotic effect for number of primary branches per plant. Highest significant positive heterosis for number of secondary branches per plant and for number of silique per plant over better parent as well as mid parent was found in BARI Sar-6 × Local Tori-7. Significant negative heterosis over mid parent and better parent was found in SAU proposed 4 and thus these can be used for producing variety with earliness. Highly significant and positive value for both mid parent and better parent was represented by Local Tori-7 × Yellow Special. The variance due to GCA and SCA were highly significant for all the characters studied. The parent BARI Sar-17 was an excellent general combiner for dwarfness. For number of secondary branches, Seed yield per plant and the number of siliqua highly significant and positive GCA effects were observed in Local Tori-7. BARI Sar-17 exhibited the highest significant and positive GCA effects for seed per silique and can be considered as a good general combiner. Yellow Special × SAU proposed 4 was the best specific combiner for dwarfness where as Local Tori-7 × BARI Sar-17 for primary branches per plant and Local Tori-7 × BARI Sar-15 siliqua per plant. Yellow Special × BARI Sar-14 was the best specific combiner for seed yield per plant and SAU proposed 4 ×Local Tori-7 for seeds per siliqua.The GCA and SCA ratio for all the characters except seed yield per plant were more than one indicating that these characters were predominantly under additive genetic control.