1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Dragon fruit is an exotic fruit crop commonly referred to as Pitaya, is perennial in naturewith a life span of 20 years(Department of Fruit Science, College of Agriculture , Vellanikkara, 2023-03-02) Aarthi, M.; Aswini, ADragon fruit is an exotic fruit crop commonly referred to as Pitaya, is perennial in naturewith a life span of 20 years. The production of dragon fruit is on the increase in Kerala due to its wide adaptability and high nutritional properties. As it is an exotic fruitcrop, the information on flowering, phenology and ideal genotypes under Kerala condition is lacking. So information on genotypes and reproductive biology of dragon fruit will be aboon to farmers and also to the researchers for future breeding programmes. The current investigation entitled “Reproductive biology and evaluation of dragon fruit (Hylocereus spp.) genotypes” conducted in the college orchard of the Department of Fruit Science, Vellanikkara during the period of 2021- 2023 throws light on this aspect. Two experiments were conducted as a part of the study, one for assessing the yield and quality of different dragon fruit genotypes,and the other for investigating the reproductive biology and phenology of different dragon fruitgenotypes. Five dragon fruit genotypes, namely Cambodian Red, Malaysian Red, Oregano Red, Srilankan Red and Cambodian White were evaluated during this research study. In the first experiment, when the different parameters related to stem, yield and quality were studied, significant variations could be observed among the genotypes. With regard to quantitative stem characteristics, Cambodian White exhibited highest stem segment width (33.05 mm), arch height (4.62 cm) and distance between areoles (35.08 mm) and the least number of spines per areole (2.13). When qualitative stem characteristics were considered, Oregano Red exhibited strong waxiness with a flat margin and prominent dark brown colouredspines on areoles making it distinctly different from the other genotypes. When the quantitative fruit characteristics were observed Oregano Red produced fruits having highest fruit width (8.62 cm), fruit girth (27.84 cm) and number of bracts on fruit (28.07cm), whereas minimum fruit width (6.65 cm) and fruit girth (22.34 cm) were recorded in Malaysian Red. The highest bract width was recorded in Cambodian White (35.00) with less number of bracts in fruits (19.21), and lowest bract width was observed in Malaysian Red (25.52). The length of apical bract was highest in Cambodian Red (42.66 mm), whereas it wasabsent in Oregano Red. Among the fruit parameters studied, highest fruit weight (411.33 g), peel weight (134.82g) and pulp weight (276.47g) were recorded in Oregano Red and lowest in Malaysian Red. Cambodian Red recorded the highest number of seeds (2045 per 50 g of fruit pulp) but small in size, whereas Oregano Red had the least number of seeds (820.00 per 50 g of fruit pulp) but larger in size. The pulp to fruit weight ratio was highest in Cambodian Red (0.74) followed by Srilankan Red (0.72), indicatingthe presence of thin peel in these genotypes. On contrary, Cambodian White had the lowest pulp to fruit weight ratio (0.63) indicating the presence of thick peel in this genotype. Regarding the number of fruits per pole, Malaysian Red recorded the maximum numberof fruits per pole (17.60), followed by Cambodian Red (11.8). However, the fruit yield (kg per pole), of both Cambodian Red (3.79 kg) and Malaysian Red (3.68 kg) were found to be on par.This result revealed that Malaysian Red produced smaller fruits when compared to Cambodian Red. The number of fruits per pole were least in Oregano Red (3.6 fruits per pole) and was onpar with Srilankan Red (4.6 fruits per pole) resulting in reduced yield in Oregano Red (1.29 kg/pole) followed by Srilankan Red (1.54 kg per pole). Oregano Red and Cambodian White were distinct from the other genotypes with respectto fruit morphological features. With regards to the position of the fruit bract towards the peel,the bracts were slightly held out in Cambodian White, while bracts were strongly held out in Oregano Red. Considering the peel and pulp colour, Cambodian White had medium pink colour with white flesh, whereas, Oregano Red exhibited red coloured peel and dark pink pulp.Regarding the shape of the fruit, Cambodian White produced oblong fruits, while the fruits of Oregano Red were spherical in shape. Biochemical analysis of the fruits clearly indicated that there exists significant variationsamong the dragon fruit genotypes with respect to total soluble solids (TSS), TSS/acid ratio and anthocyanin content. Srilankan Red and Cambodian White recorded the highest and lowest values respectively for both TSS (13.78 °Brix and 10.18 °Brix) and TSS/acid ratio (107.66 and79.55). Oregano Red recorded the highest anthocyanin concentration (0.27 mg/g), whereas Cambodian White (0.01 mg/g) recorded only very low concentration of anthocyanin. Other biochemical parameters, such as acidity, ascorbic acid content, reducing sugar and total sugardid not exhibit any significant variation among the genotypes. In the second experiment, flower characteristics such as flower bud length and girth, pericarpel width, length of perianth, distance of anther below stigma, number of stigma lobes,number of flower flushes and the number of flowers per pole varied among the genotypes. Withregards to flower production, Malaysian Red produced highest number of flowers (23.0 flowersper pole) while Srilankan Red produced less number of flowers (4.8 flowers per pole). The number of flower flushes per year varied among the genotypes, where Cambodian Red and Malaysian Red recorded seven flower cycles per year, Srilankan Red and Cambodian White exhibited five flower cycles per year, while in Oregano Red only four flower flushes were observed per year. In terms of qualitative flower characteristics, Cambodian White and Oregano Red were found to significant vary from the other genotypes. Both Oregano Red and Cambodian White exhibited circular bud shape with rounded apex. Regarding the flower colour, the primary colour of sepals and petals of both genotypes were green and white, respectively, whereas the secondary colour of sepal in Oregano Red exhibited a strong red edge on sepals, and that of Cambodian White featured no red colour on the sepals. The sex form, nature of stamen and shape of the bract did not differ among all the genotypes. Hermaphrodite sex form with free stamen was observed in all the dragon fruit genotypes under study. Phenological parameters clearly indicated that there exists variation among the genotypes. Early bud initiation was recorded in Malaysian Red (291.6 days) and late bud initiationobserved in Oregano Red (388.0 days). From the observation recorded, the genotype OreganoRed was observed to take maximum number of days for flowering (18.00), fruit set (4.06) and harvest (28.22 days) when compared to other genotypes. Cambodian White (26.34 days) took only minimum number of days for fruit harvest from fruit set. During the study period flowering season was observed to start from the month of May for Malaysian Red and Cambodian Red and in Oregano Red flowering was delayed and found to start only in the last week of June. The fruiting season of Cambodian Red and Malaysian Red started from June and continued up to last weekof October while in other genotypes flowering started from July and continued till October. In the pollen study, the highest pollen viability of 100% was observed in Oregano Red, Srilankan Red and Cambodian White. The genotypes did not significantly vary for pollen sizeand length of pollen tube, as it ranged from 0.08 to 0.09 mm and 0.203 to 0.250 mm respectively. In the compatibility study, all self and cross pollinations resulted in successful fruit set (100%), except for Oregano Red which exhibited only 33.3% self compatibility. Cluster analysis of stem, flower and fruit qualitative characters provided four clusters at 70 % similarity coefficient and it could be inferred that, Cambodian Red and Malaysian Red were closely related to each other, indicating a possibility of belonging to the same species. The other clusters were found to exhibit variations among them, even though, they originated from the same species, indicating the presence of more than one genotype in the same species. Based on the current research, it can be inferred that the best genotype with the highest yield and largest fruits was Cambodian Red. Oregano Red was found to have the highest anthocyanin concentration and Srilankan Red recorded the highest total soluble solids, makingboth suitable for value addition. Despite being members of the same species (H. costaricensis),the morphological characteristics of Malaysian Red, Srilankan Red and Cambodian Red differed from one another. Oregano Red (H. polyrhizus) and Cambodian White (H. undatus) displayed wide genetic variation as they belong to different species. Morphological, biochemical and phenological characterization of five dragon fruit (Hylocereus spp.) genotypes revealed the presence genetic variations among them which could be used as a key trait for distinguishing three different species.Item Standardization of vegetative propagation techniques in dragon fruit( Hylocereus spp.)(Department of Fruit Science, College of Agriculture , Vellanikkara, 2023-02-02) Mohammed Billal, M.; Aswini, ADragon fruit which belong to the family Cactaceae is commonly referred to as Pitaya, Pithaya, Queen of the Night, Night blooming Cereus. It is one among the exotic fruits, cultivated primarily for its attractive and highly nutritious fruit. It is native to Costa Rica, Guatemala and Southern Mexico, and are primarily found in tropical and subtropical regions. Though this can be easily multiplied through seeds, seedlings are not preferred as they have a long pre-bearing age and also not true to type in nature. Among the vegetative propagation methods, cuttings alone are used for mass multiplication of planting materials all over the world, whereas layering, grafting and budding are not in commercial use. Hence, the present study entitled “Standardisation of vegetative propagation techniques in dragon fruit (Hylocereus spp.)” was carried out in the Department of Fruit Science during 2022-2023, comprising three experiments: standardisation of length of rooted cuttings for propagation, standardisation of propagation by air layering and standardisation of propagation by grafting with the objective of evaluation of different vegetative propagation methods in dragon fruit. In the first experiment, the performance of different length of rooted cuttings were evaluated. Rooted cuttings of 120 cm length (T4) were found to be the best as it produced the maximum number of segments (13.10), number of newly emerged segments (3.70), number of spine areoles (556.00), number of roots (14.00), longest root (52.50 cm), duration of flowering (107.80 days), number of fruits (19.2 fruits/pole) and fruit yield (4.96 kg/pole). Flower and fruit morphology did not exhibit any significant variation with the treatments, as the same variety (“Cambodian Red” – red fleshed variety) was used for the study, and the flowering and fruiting characters are associated with the genetic nature of the variety. In the second experiment, the different rooting media for air layering were evaluated. Coirpith compost (25.00 days) and Arbuscular Mycorrhizal Fungi (AMF) with perlite and vermiculite (26.50 days) recorded the minimum number of days for root emergence. Sphagnum moss recorded the maximum number of adventitious roots per air layer (15.30). Longest roots were observed in AMF with perlite and vermiculite (11.04 cm) and sphagnum moss (10.85 cm) and were found to be on par with each other. The AMF with perlite and vermiculite (5.45 mm) and sphagnum moss (5.38 mm) recorded maximum root diameter. In terms of survival percentage, sphagnum moss recorded the highest survival percentage of 81.25%. Sawdust (3.33 air layers) and sphagnum moss (3.25 air layers) produced the maximum number of rooted air layers after 90 days of air layering. In the third experiment, different grafting methods were evaluated with two varieties of dragon fruit, Mexican Red and Malaysian Red. When Mexican Red was used as the rootstock, horizontal grafting (T1) (16.00 days), shoot grafting (T3) (18.50 days) and seedling grafting (T6) (18.80 days) recorded the minimum number of days taken for sprouting. Horizontal grafting recorded the maximum number of segments (2.00). V-cut bud grafting (T5) and seedling grafting (T6) did not produce any segments. Shoot grafting recorded the longest segments (101.80 cm) and maximum survival percentage (100%). The girth of the rootstock did not vary in both the rootstocks. The maximum girth of the scion (135.20 mm), maximum scion length (117.40 cm) and taller grafts (158.40 cm) were observed in shoot grafting. When Malaysian Red was used as the rootstock, the minimum number of days for sprouting were recorded for seedling grafting (15.75 days) and horizontal grafting (16.20 days). Bone grafting (T4) (1.40), horizontal grafting (1.33) and shoot grafting (1.33) recorded the maximum number of segments. Horizontal grafting produced the longest segments (115.50 cm). Shoot grafting and L-grafting recorded the maximum survival percentage (100%). The maximum girth of the scion was observed in shoot grafting (148.50 mm). The length of the scion was the maximum for horizontal grafting (T1) (131.30 cm) and shoot grafting (T3) (116.50 cm). Both horizontal grafting (165.10 cm) and shoot grafting (158.80 cm) produced taller grafts. Initially, the success percentage was the highest in horizontal grafted plants thereafter shoot grafting recorded the highest percentage throughout the study when Mexican Red was used as the rootstock. When Malaysian Red was used as the rootstock horizontal grafting recorded the highest success percentage at 15 days after grafting. But, 30 to 75 days after grafting shoot grafting recorded the highest percentage. Finally, shoot grafting and L-grafting were found to be the best with maximum success percentage. The percentage of graft establishment was highest in shoot grafting at 30, 60 and 90 days after grafting when both rootstocks were used. Additionally, L-grafting recorded the highest graft establishment at 90 days after grafting when Malaysian Red was used as the rootstock. The method of V-cut bud grafting (T5) was considered as a failure one with no success percentage. The present research revealed that using 120 cm long rooted cuttings (T4) (4 feet) is the most suitable planting material for dragon fruit in order to produce the highest yield, longest fruiting period, the largest number of fruits and significant improvement in vegetative characteristics. Sphagnum moss (T3) was found to be the most effective rooting medium for air layering in dragon fruit due to its higher success rate. The best grafting technique for dragon fruit was found to be shoot grafting (T3), which produced maximum scion girth, scion length, graft height and success percentage.Item Evaluation of dragon fruit (hylocereus spp.) genotypes grown in Kerala(Department of Fruit Science, College of Agriculture, Vellanikkara, 2021) Keerthana Sethunath; Jyothi BhaskarDragon fruit (Hylocereus spp.) commonly known as the pitaya, is a perennial climbing vine belonging to the Cactaceae family. The present work carried out in the Department of Fruit Science during the period 2019-2021 to study the morphology, flowering, yield and quality attributes of dragon fruit grown in four districts of Kerala (Thiruvananthapuram, Pathanamthitta, Ernakulam and Thrissur) is of vital importance with respect to the popularity dragon fruit has gained within a very short span of time in Kerala. A total of 100 plants, 10 each from 10 different locations were evaluated based on the UPOV descriptor guidelines to characterise the different genotypes that are being cultivated in Kerala. The plants were denoted as P1 to P10, prefixed with the first two letters of the location to which they belong. The commercial cultivation of dragon fruit in Kerala was found to be dominated by the dark pink/purple fleshed dragon fruit (Hylocereus costaricensis). Within this species, more than one genotype was identified. The stem, flower, yield and quality attributes were found to vary widely. The stem characters included stem segment length (33-210 cm), stem segment width ((1.80-6.60cm), distance between areoles (2.00-5.50 cm), arch height (1.00-4.20 cm), stem waxiness (strong and weak), stem sturdiness (high and low), margin of rib (convex and flat), number of spines per areole (3-5), spine colour (medium brown and dark brown), height of the pole (6.5-8 ft with 1-2 ft buried underground), number of branches (numerous) and number of stem segments per branch (1-6). Variations were also observed for the flower characters such as bud shape (ovate and elliptic), shape of bud apex (acute and rounded), secondary colour pattern of sepal (slightly red edged and red edged), intensity of red colour on bracts (weak, medium and strong), length of style (23.50-31.00 cm) and number of stigma lobes (26-36). The yield characters studied were fruit weight (84-896g), length of fruit (4.60-10.40 cm), width of fruit (4.40-10.40 cm), length/width ratio of fruit (1.00-1.21), number of bracts (18- 50), length of apical bract (3.00-6.30cm), width of base of the bract(1.40-5.70 cm), position of bracts towards the peel (adpressed, slightly held out and strongly held out), fruit weight without peel (52-592 g), fruit shape (oval or spherical), colour of peel 2 (medium pink and dark pink), flesh colour (dark pink and purple) and yield per post (5- 20 kg per year based on the age of the plants). The values ranged from 11 to 18 °B with respect to the TSS of the fruits whereas the titrable acidity was found to be 0.12 per cent in all the fruits. The plants KoP1 to KoP10 from Kozhenchery received the maximum score for appearance, taste, flavour, after taste and overall acceptance. Plants came into bearing within 1.5 to 2 years of planting when stem cuttings were used as the planting material. The duration from flower bud initiation to anthesis was 12-15 days in general and anthesis took place during the night time after 10 p.m. If the pollination was successful, fruit could be visible after 5 to 7 days of anthesis and the harvest was possible in 23-25 days from fruit set i.e., one month after anthesis. When the phenology of the plants was studied, flowering started in the month of March in two locations (Athikkayam and Vaniyampara) whereas in all the other locations, it started in the month of April. The flowering season extended till September to October. The fruiting season started exactly one month after the anthesis and ceased one month after the flowering has stopped, i.e., April to November. As dragon fruit was a perennial crop, different orchards were grouped into three phases based on the age of the plants, namely the establishment phase (0-2 years), yield increasing phase (2-4 years) and yield stabilizing phase (4 years and above). Considering the phases, total cost of cultivation was calculated and it was found to be ₹8,29,393 per year per hectare. The maximum cost during establishment phase was incurred for the planting material and construction of posts. During the maintenance phase, maximum expenditure was for the manure and fertilizer application. Average yield per year per hectare was observed to be around 21 tonnes and the average price received by farmers was ₹174 per kg. Net return from one hectare was around ₹27,32,768. The B:C ratio was 4.29 when the farmers received ₹174 per kg fruit. The B:C ratio obtained with the least price (₹120 per kg) was 3.04. Being a highly remunerative crop, area under dragon fruit cultivation was found to be expanding year after year, as more under-utilized lands are being brought under this crop. Major constraint identified in the cultivation of dragon fruit was the bud and flower drop due to excessive and continuous rainfall during the flowering season. Weed 3 growth was also found to be a major problem. The source of planting material in all the locations under study were found to be either from Malaysia or Cambodia. Since dragon fruit was a crop introduced recently to India, the incidence of pests and diseases were less compared to other fruit crops. But the menace caused by ants was common and rarely, mealy bugs and beetles were found. Fruits were found to be damaged by birds. Disease symptoms similar to canker were observed on the fruits and stem in one of the locations. Physiological disorder like yellowing during extreme summer was common in most of the orchards and these symptoms vanished immediately after a shower or with irrigation. The variability within the species was analysed using statistical techniques like factor analysis and cluster analysis. Maximum variability (59.38%) in the stem and flower characters was explained by two dimensions. The characters that contributed to the variability were intensity of red colour of bract, stem waxiness, stem sturdiness, margin of rib, spine colour, bud shape, bud apex shape, number of stigma lobes, length of style and distance between areoles. Similarly, maximum variability (62.74%) in the quality attributes were contributed by the first two dimensions out of four significant dimensions. The characters responsible for creating the variability were fruit weight, position of bract towards peel, fruit width, fruit weight without peel, fruit length, flesh colour, fruit shape, width of base of bract, length of apical bract, outer TSS, TSS-acid ratio and core TSS. Cluster analysis of the qualitative traits formed six different clusters. When the mixed data with both qualitative and quantitative characters were analysed through clustering, there were three clusters based on the stem and flower characters and four clusters based on the yield and quality attributes, which indicated variability within the species. Other species of Hylocereus namely H. undatus and H. megalanthus, and other types known as Bruni and Frankis Red imported from countries like Thailand and Vietnam are also under cultivation by farmers and are getting popular in different parts of Kerala.