Study of Comparative Morphology of Eight Cultivated Genotypes of Olea europaea L

Abstract

The current study was designed to assess the comparative morphology of eight olive cultivars with different geographical origins and diverse genetic backgrounds, introduced to a new climatic zone. The morphological parameters of eight (five exotic and three domestic) olive cultivars (Bari Zaitoon-1, Bari Zaitoon-2, Favolosa (FS-17), Koroneiki, Balkasar, Ottobratica, Leccino, and Arbequina) were compared at the experimental area of the Department of Botany, The Islamia University of Bahawalpur, Pakistan (29°24′0″ North, 71°41′0″ East, 401–421 feet above sea level). Plant height, number of leaves/15 cm shoot, leaf size characteristics (leaf length, leaf width, leaf area, and length/width ratio), leaf shape characteristics (margin, leaf axil, base, and apex angles), leaf pigments (Chlorophyll a, Chlorophyll b, total chlorophyll contents, and carotenoids), phyllotaxy, and leaf color and venation were recorded. The highest plant height (28 cm) was obtained by Bari Zaitoon-2 followed by Bari Zaitoon-1 (24 cm), both of which are domestic cultivar of Pakistan, while the shortest height (5 cm) was obtained by Koroneiki. Leccino displayed the highest average number of leaves (17.8) on main shoot, followed by BARI-2 (16.4) and the lowest score was from Balkasar (10.4). Leaf area ranged from 5.66 cm2 (Bari Zaitoon-1) to 3.08 cm2 (Koroneiki). The longest leaf length (5.74 cm) was found in Bari Zaitoon-1 and the shortest (4.04 cm) in Koroneiki, while the broadest leaves were found in Leccino (1.54 cm) and the narrowest (1.12 cm) in Koroneiki. Bari Zaitoon-2 led in leaf length to width ratio (4.058) followed by Bari Zaitoon-1 (3.772) with small lanceolate leaves hardly reaching the value of 4, with the lowest value illustrated by Leccino. The total chloroplast pigments were highest in FS-17 followed by Bari Zaitoon-1 and Bari Zaitoon-2, while the lowest was in Arbequina. Chlorophyll a was highest in Bari Zaitoon-1 followed by FS-17 and Balkasar, with the lowest rate in Arbequina. Chlorophyll b content of FS-17 was the highest whereas the Chlorophyll b and total chlorophyll contents in Arbequina were the lowest of all the cultivars. The highest value of total carotenoids was found in Balkasar followed by FS-17 with the lowest value in Arbequina. The phyllotaxy was categorized into three types, i.e., alternate, opposite, and whorled. The combination of two or more types was usually observed on the same branch. The whorl of four leaves was also present in rare cases. Leaf venation was both pinnate and reticulate. The leaf base of most (four) of the olive cultivars, i.e., Arbequina, Balkasar, Leccino and FS-17, were cuneate having acute, rounded, apiculate, and cuspidate leaf tips, respectively. The findings revealed remarkable variations in olive morphology, especially in the leaves and a successful record of the preliminary data of olive cultivars from the study area was made. The present research demonstrated that local olive cultivars have unique characteristics that differentiate them from imported cultivars. Thus, local cultivars provide novel genetic resources that should be conserved.