Pakistan is inherently deficient in forests and recently high rate of deforestation, overexploitation, illegal logging, and climate change further exacerbated the forest cover. Arable land is mainly used for crop production therefore forest cover can be increased through afforestation and reforestation of marginal or deserted lands. Acacias are multifunctional and known for a wide adaptation to marginal and deserted lands. However, acacia species are known to naturally hybridize, and reports of natural polyploids have been made. Thus, knowledge of the ploidy of focal species is essential for programs including afforestation, reforestation, polyploidization, hybridization, and mutation breeding. The goal of this work was to identify the ploidy level of acacia species found in Pakistan based on stomatal characteristics and genomic DNA contents and compare both approaches to find the most economical and reliable ploidy detection method. The ploidy of the species under investigation was accurately determined by both approaches, according to the results, when stomata length, width, and genomic DNA were compared to previously published data. It had been shown that the 2C-value for genomic DNA content, stomata length, width, and diploid status of each investigated species varied significantly from one another. All species had stomata present on both adaxial and abaxial leaf surfaces except A. modesta. A. modesta may have low transpiration losses as compared to other species and therefore may be a preferred species in extreme dry conditions of Pakistan. The stomata's length varied between 7.83 and 31.5 µm, while their breadth varied between 5.08 and 22.67 µm. Acacia radiana possessed the longest and widest stomata, while A. nilotica had the shortest and narrowest. A. catechu had a tiny genome while A. auriculiformis had a large genome, with genomic DNA ranging from 1.022 pg to 1.523 pg. According to this study, both methods for determining the ploidy of acacia species can efficiently be used to identify polyploids. Nevertheless, stomata length and width proved technically less demanding and cheaper method, thus may be a method of choice for ploidy determination in acacia. Flow cytometry, on the other hand, has the greatest advantage of providing a direct and high throughput assessment of DNA but is technically more demanding and expensive.

Keywords: Acacia., Deforestation., Afforestation., Reforestation., Ploidy., Stomatal characters., Flow Cytometry