1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Morphological and biochemical characterization of exotic fruit crops of sapotaceae family(Department of Fruit Science, College of Agriculture ,Vellanikkara, 2025-02-10) Amal Kishore, M.; Aswini, AThe Sapotaceae family includes a variety of tropical fruit crops known for their ecological and nutritional importance. Among these, abiu (Pouteria caimito) and star apple (Chrysophyllum cainito) are gaining attention for their unique qualities and potential benefits. These fruits are rich in nutrients, including phytochemicals, vitamins, minerals, and antioxidants, which make them valuable for promoting health and diversifying agricultural systems. Kerala's tropical climate provides favorable conditions for cultivating abiu and star apple, making them suitable additions to the state’s fruit crops. These fruits contribute to biodiversity while offering new market opportunities for farmers. Their distinct flavors and high nutritional value make them attractive to consumers, often commanding premium prices and increasing farm incomes. Although these fruits are now being grown commercially in Kerala, there is limited research on their growth, flowering, fruiting, and yield under local conditions. Understanding these aspects is essential to improve their cultivation and realize their full potential. The study on abiu (Pouteria caimito) was carried out across four distinct agroecological locations in Kerala: Kottayam, Thrissur, Malappuram, and Kozhikode. A total of 34 genotypes were collected from these regions and was evaluated for their morphological, biochemical, physiological, and phenological traits. Analysis of the genotypes revealed significant variability across morphological, biochemical, and other characteristics, highlighting the diversity present within these collections. The yield of abiu trees varied significantly across genotypes, highlighting their diverse genetic potential for production. Collection 01 stood out with the highest yield of 301.24 kg/tree, followed by Collection 26 (57.70 kg/tree) and Collection 11 (40.08 kg/tree), which also demonstrated strong productivity. Additionally, Collections 1, 15, 26, and 25 were identified as having exceptional yield characteristics, while Collections 21 and 19 recorded the lowest yields of 1.36 kg/tree and 3.62 kg/tree, respectively. These findings emphasize the importance of prioritizing high-yielding genotypes such as Collection 01 to enhance commercial productivity. Similarly, there was considerable variation in biochemical characteristics such as total soluble solids (TSS), acidity, antioxidant content, total phenolic content, total sugar, flavonoids, and fruit protein among the abiu collections. TSS, an essential biochemical trait, ranged from 7.06 OBrix to 13.08 OBrix, with Collection 11 exhibiting the highest value. Acidity varied from 0.097 per cent to 0.102 per cent, with Collection 02 showing the maximum level. Antioxidant content was highest in Collection 06 at 7.02 AA mg/100g, which also recorded the maximum total phenolic content of 1.03 mg/g. Total sugar content ranged from 4.46 per cent to 11.16 per cent, with Collection 07 leading in this trait, while flavonoid content peaked at 0.97 mg/g in Collection 17. Fruit protein content showed significant variation, with Collection 14 having the highest value of 1.90 mg/g. Based on these biochemical traits, Collections 11, 02, 06, 07, 17, and 14 were identified as superior genotypes. There was significant variation in physiological parameters such as relative water content, excised leaf water loss, membrane stability index, leaf thickness, lipid peroxidation, and epicuticular wax content among the abiu collections. Relative water content ranged from 54 per cent to 92 per cent , with Collection 30 recording the highest value. Excised leaf water loss was minimal in Collection 01 at 0.55 per cent, while membrane stability index was the highest in Collection 07 at 84.39 per cent. Leaf thickness varied from 205 × 10⁻³ mm to 280 × 10⁻³ mm, with Collection 33 showing the greatest thickness. Lipid peroxidation values ranged from 0.0093 mg/g to 0.0143 mg/g, with Collection 05 having the lowest value, indicating better oxidative stress tolerance. Epicuticular wax content showed notable variability, with Collection 30 having the maximum value of 0.57833 mg/g. Based on these physiological traits, Collections 30, 01, 07, 33, and 05 were identified as superior genotypes. The dendrogram analysis grouped the genotypes into four clusters. Cluster I contained five genotypes (11, 7, 22, 30, 33), while Cluster II had sixteen genotypes (27, 28, 18, 23, 34, 5, 26, 29, 31, 19, 20, 8, 16, 17, 24, 25). Cluster III comprised only one genotype, Collection 01, highlighting its unique traits, and Cluster IV included the remaining genotypes (14, 4, 10, 9, 12, 21, 32, 6, 13, 15). This analysis underscores the genetic diversity among the collections, with Cluster III being particularly distinct. ELISA was conducted on fruiting and non-fruiting types of Pouteria caimito to study hormonal variations. The analysis showed clear differences in hormone levels between the two types. Auxin was higher in the petiole and flower head of fruiting types, highlighting its role in supporting cell growth and development necessary for fruiting. However, auxin levels in the whole flower and ovary were similar in both types, suggesting that other factors may influence fruit formation in these parts. Cytokinin levels also showed variation, with fruiting types having more cytokinin in the ovary, aiding cell division and fruit development. In contrast, non-fruiting types had higher cytokinin levels in the petiole and flower head, possibly diverting resources and reducing fruiting success. This study demonstrates how auxin and cytokinin distribution in different plant parts influences the fruiting process in abiu. Anatomical studies of abiu fruit stalks showed significant differences between fruit-setting and non-fruit-setting types. Non-fruit-setting types had a smaller section diameter (1747.89 µm vs. 3437.60 µm), lower vesicle density (0.000244 vesicles/µm² vs. 0.000893 vesicles/µm²), and smaller vesicle diameter (29.4 µm vs. 38.09 µm). These structural differences highlight their role in fruit development. The study on star apple (Chrysophyllum cainito) was conducted with nine collections, eight of which were sourced from different parts of Thrissur, and one from Kozhikode in Kerala. These genotypes were systematically evaluated for their morphological, biochemical, physiological, and phenological traits. The analysis revealed significant variability across the studied characteristics, highlighting the diversity present within these collections and their potential for further research and utilization. The analysis of star apple collections revealed significant variation in morphological traits and fruit yield. Collection 09 emerged as the best performer with the tallest tree height (7.48 m) and the highest fruit yield per tree (24.98 kg). It also recorded the largest fruit weight (246.95 g) and the longest fruit length (8.82 cm), making it ideal for high-yield purposes. In contrast, Collection 08, though having a shorter tree height (4.72 m), stood out for its extended shelf life (6.89 days), highlighting its potential for storage and marketability. Other morphological parameters, such as inflorescence length and flower density, varied across collections, with Collection 02 having the longest inflorescence (1.39 cm) and Collection 01 exhibiting the maximum number of flowers per inflorescence (30.76). In terms of biochemical traits, Collection 06 excelled with the highest antioxidant capacity (18.22 AA mg/100 g), total sugar content (15.13 per cent), and phenolic content (2.87 mg/g), making it a valuable choice for health-oriented applications. Collection 08 showed the highest TSS (19.65 °Brix) and protein content (2.83 mg/g), indicating superior fruit quality. Meanwhile, Collection 07 had the highest acidity (0.10267 per cent), which could contribute to its unique flavor profile. These biochemical differences highlight the diverse nutritional potential of the collections. Physiological traits also showed marked differences, with Collection 08 leading in leaf sugar (28.37 mg/g), leaf protein (26.07 mg/g), and membrane stability index (80.75 per cent), suggesting better stress tolerance and overall vigor. However, Collection 01 displayed the highest relative water content (66 per cent), which is critical for maintaining hydration under varying environmental conditions. These findings underline the importance of both biochemical and physiological traits in identifying superior genotypes, with Collections 09, 08, and 06 standing out as the most promising for further cultivation and improvement. Anatomical studies on the fruit stalks of star apple accessions revealed that stalk characteristics influence fruit size. Longer stalks, such as in Collection 07 (21.01 mm), do not necessarily result in larger fruits, as seen with a fruit size of 55.42 mm. However, thicker stalks, like in Collection 06 (6.9 mm), were associated with larger fruits, measuring 68.3 mm. This highlights the importance of stalk diameter over length in supporting fruit size. Future research on abiu and star apple should focus on molecular characterization of genotypes to identify key genetic markers and traits influencing their superior performance. Multilocation trials across diverse environments should be conducted to understand their climate adaptability and ensure consistent productivity. As both crops are sexually propagated, variability and the lack of uniform planting materials remain significant challenges. Developing and distributing high-quality planting materials will play a crucial role in promoting these crops. Abiu and star apple are not only promising fruit crops for the future but also highly nutritious, rich in antioxidants, and beneficial for health. Their antioxidant properties can combat oxidative stress, contributing to better health outcomes, while their unique taste and texture make them appealing to consumers. These novel fruit crops are also essential for enhancing biodiversity, offering opportunities to diversify farming systems and reduce dependency on traditional fruit crops. By introducing these underutilized species into cultivation, we can increase genetic diversity, support ecological balance, and create new market opportunities for sustainable agriculture. Their potential to combine health benefits, biodiversity enhancement, and consumer appeal positions them as key crops for future agricultural development.