Comparative study of chlorophyll content in diploid and tetraploid black wattle (Acacia mearnsii)

The effects of the number of chromosome sets on chlorophyll content in diploid and tetraploid black wattle were assessed through chlorophyll absorbance. Seedlings of similar to 8 months of age, 1-year-old trees in polybags and 2-year-old field material were selected for this investigation. Three families per ploidy level comprising of 10 half-sibs per family were used in the analysis. An analysis of variance revealed significant differences (P < 0.05) in chlorophyll absorbance between diploid and tetraploid materials ((A) over bar = 0.375 and (A) over bar = 0.653, respectively). Significant differences ( P < 0.05) between treatments ( seedling, bagged material and. field material) within each ploidy level were recorded, where chlorophyll absorbance increased from diploid bagged trees ((A) over bar = 0.343) to seedlings ((A) over bar = 0.375) to field trees ((A) over bar = 0.408). Similar significant increases were recorded for the tetraploid seedlings (A = 0.629) to bagged trees ((A) over bar = 0.644) to field trees ((A) over bar = 0.686). Significant differences (P < 0.05) were also recorded between genetic lines within both ploidy levels. However, when comparing families within each ploidy level, with respect to treatment differences, in most cases, two of the three families showed no significant differences (P > 0.05). Within each family, significant differences (P < 0.05) were recorded between each of the three treatments tested, with the field material consistently having significantly (P < 0.05) greater amounts of chlorophyll.