Back to Contents

Pak. J. Bot., 44(3): 1013-1020, 2012.

FREE FULL TEXT PDF

HETEROTIC STUDIES AND INBREEDING DEPRESSION IN F₂ POPULATIONS OF UPLAND COTTON

MARIA KHAN PANNI¹, NAQIB ULLAH KHAN², FITMAWATI³, SUNDAS BATOOL² AND MARYAM BIBI²

Abstract: To study the genetic potential, heterotic effects and inbreeding depression, 8 × 8 F₂ diallel populations with parental lines of upland cotton were grown during crop season 2010 in a randomized complete block design at Khyber Pakhtunkhwa Agricultural University Peshawar, Pakistan. Highly significant (p≤0.01) variations were noticed among parental lines and F₂ populations for all the traits. According to genotypes mean performance for various traits, plant height varied from 101.60 to 126.30 cm and 98.60 to 140.60 cm, bolls plant^-1 (12.87 to 19.53; 12.13 to 22.60), boll weight (3.80 to 5.01 g; 3.04 to 5.38 g) and seed cotton yield plant^-1 varied from 55.74 to 85.47 g and 45.57 to 96.05 g in parental cultivars and their F₂ populations, respectively. However, 12 and 7 F₂ populations manifested significant heterosis over mid and better parents for plant height, 7 and 3 for bolls plant^-1, 13 and 9 for boll weight and 13 and 5 F₂ populations for seed cotton yield plant^-1, respectively. F₂ populations i.e. CIM-554 × CIM-473, CIM-554 × CIM-499, CIM-496 × SLH-284, CIM-473 × CIM-446 and CIM-554 × SLH-284 with low mean values for plant height performed better and manifested highly significant heterotic values over mid and better parents for bolls per plant, boll weight and seed cotton yield. By comparing F₂ mean values with F₁s, inbreeding depression was observed for plant height (0.66 to 23.99%), bolls per plant (5.00 to 63.16%), boll weight (0.20 to 23.24%) and seed cotton yield (0.44 to 75.52%). However, 62% of F₂ populations revealed negative values for inbreeding depression, 14% for bolls per plant, 77% for boll weight and 21% for yield, revealed that these F₂ populations were more stable and performed better than F₁s even after segregation. Although, F₂ populations may display less heterosis as compared to F₁s, but still better than high parents and can be used as hybrid cotton to skip the expensive F₁ hybrid seed production.

¹Institute of Biotechnology and Genetic Engineering, Khyber Pakhtunkhwa Agricultural University, Peshawar, Pakistan

²Department of Plant Breeding and Genetics, Khyber Pakhtunkhwa Agricultural University, Peshawar, Pakistan

³Department of Biology, Faculty of Science and Mathematics, Riau University, Indonesia