Breeding bread wheat for low phytic acid using full diallel crosses

Phytic acid (Myo-inositol 1, 2, 3, 4, 5, 6 hexa-kisphophate) is a storage form of phosphorus and can accumulate to levels as high as 35% in the wheat kernel. Phytic acid acts as an anti-nutritional macromolecule (anti-nutrient) in the wheat kernel. Due to its inhibitory role, a high concentration of phytic acid is undesirable as it hinders the bioavailability of some essential nutrients such as Fe, Mg, Ca, Zn and Cu, etc. To see the inheritance of phytic acid in wheat, phytic acid concentration was initially determined in kernels of 10 wheat genotypes to identify two contrasting genetic groups for diallel analysis. Based on pre-screening results of 10 wheat genotypes, five wheat genotypes (3 with high and 2 with low phytic acid concentration) were crossed in all possible combinations during 2007-08 to generate a 5 x 5 full diallel set for studying the inheritance of phytic acid and other agronomic traits. All 20 F1 hybrids and 5 parental genotypes were planted using a randomized complete block design with three replicates during 2008-09 at Khyber Pakhtunkhwa Agricultural University, Peshawar. Analysis of variance revealed significant differences for all traits, providing justification for diallel analysis. According to Hotelling's t2 test and regression analysis, the additive-dominance model was adequate for phytic acid, plant height, flag leaf area, partially adequate for days to heading and grain filling duration. Values of D greater than H1 and H2 for flag leaf area and plant height indicated their additive nature, whereas values of D less than H1 and H2 for grain filling duration and phytic acid concentration accounted for non-additive control of these traits. The narrow and broad sense heritability estimates varied widely among traits for days to heading (0.07, 0.32), flag leaf area (0.31, 0.55), grain filling duration (0.24, 0.91), plant height (0.12, 0.28) and phytic acid concentration (0.01, 0.86). The values for phytic acid concentration ranged from 0.56 to 3.43% among F1 hybrids and 1.06 to 3.67% for parental genotypes. The F1 hybrids, Ps-2005 x Ghaznavi (0.56%), AUP-4006 x Ps-2004 (0.74%), Janbaz x Ps-2004 (0.89%) and Janbaz x Ps-2005 (1.01%), had the lowest concentration of phytic acid. This research confirms that F1 hybrids with low phytic acid concentration could yield desirable segregants.