The evaluation of biodiversity in some indigenous Indian jujube (Zizyphus mauritiana) germplasm through physico-chemical analysis

Abstract

Indian jujube (Zizyphus mauritiana Lamk.) is mostly cultivated in tropical and sub-tropical regions of the world. Many native and exotic jujube cultivars are grown for fruit production in Pakistan. However, little research work has been conducted on various aspects of jujube i.e. morphological and biochemical characterization of available germplasm. Therefore, fruits of thirteen genotypes were collected to study the biodiversity through physico-chemical analysis during the years 2015 and 2016. The aim of the present study was to investigate the relationship among various physico-chemical attributes of the jujube through Pearson’s correlation that may have greater importance for breeders during the selection of desirable genotype. The cultivar Foladi had the maximum fruit weight (30.49 g), pulp weight (28.42 g) and fruit diameter (36.75 mm) among all the cultivars. The maximum fruit length was recorded in Umran-13 (45.16 mm), while the maximum seed weight (2.70 g) was found in Dilbahar. Khobani had the maximum TSS (14.92 ºBrix). The highest level of acidity (0.74%) was recorded in Gorh. Akasha had highest vitamin C content (72.53 mg 100 mL^–1 juice). The cultivars Sadqia, Umran-13, Mehmood wali, Yazman local and Gorh were much sweeter due to the maximum total sugars content (9.74–10.09%). The maximum antioxidant capacity was measured in Mahmood wali (616.13 mM Trolox 100 mL^–1), Pak white (615.02 mM Trolox 100 mL^–1) and Seedless (600.46 mM Trolox 100 mL^–1), while antioxidant activity was significantly higher in Sadqia (40.604%). The maximum amount of total phenolic content was determined in Umran-13 and Sadqia (243.06 and 239.25 µg GAE mL^–1 juice, respectively). The highly significant correlation (0.99) was observed between the fruit weight and pulp weight. Antioxidant activity and total phenolic content were also strongly correlated (0.70). Principal component analysis was made to determine the relationship among the genotypes and their variables. Dendrogram constructed on the basis of morphological attributes, divided 13 genotypes into four main clusters. Among the cultivars, Khobani and Mehmood wali share the maximum similarity (78%). Biochemical characteristics also divided the genotypes into three main clusters. The cultivars Pak white and Seedless had the maximum similarity (75%) among all the cultivars