1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)

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    Varietal evaluation of guava(Psidium guajava L.) for urban horticulture
    (Department of Fruit Science, College of Agriculture, Vellayani, 2025) Swetha, V; Simi, S
    The present research work entitled “Varietal evaluation of guava (Psidium guajava L.) for urban horticulture” was conducted at the Department of Fruit Science, College of Agriculture, Vellayani, from 2023 November to 2024 October. The study was under taken to evaluate the growth and yield response of planting materials of guava to different type and size of containers and to evaluate the growth response of different varieties of guava in containers. The experiment 1 entitled “Performance evaluation of guava (Psidium guajava L.) in containers” was laid out in Completely Randomized Design (CRD) with 18 treatments and 3 replications using the guava variety Arka Kiran. The treatments included two container types (C1 - Plastic container and C2 - Air-pot), three container sizes (V1 – 40 L, V2 – 60 L and V3 – 80 L) and three different planting materials (P1 - Air layers, P2 - Rooted cuttings and P3 - Grafts). The medium of planting consisted of soil, coir pith and farm yard manure in 1 : 1 : 1 ratio across all treatment. Twelve- month-old potted plants were subjected to the study. Plants in plastic containers (C1), registered significantly taller growth with greater plant spread, primary stem girth, number of leaves per plant (at 15, 18, and 21 MAP), stem girth (at 15 and 18 MAP), root dry weight, shoot dry weight, and leaf area (at 21 MAP) compared to those in airpots. Meanwhile, plants in airpots exhibited earlier flowering, shorter duration from flowering to harvest and longer flowering duration. They also produced greater number of fruits and higher fruit weight, length, diameter and fruit yield. Among different container volumes, 80 L (V3) had the tallest plants with the highest plant spread, stem girth and primary stem girth and the highest number of leaves per plant (15 MAP, 18 MAP and 21 MAP). In addition, they exhibited earliness in flowering and harvest, highest flowering duration, fruit weight, length, diameter, number of fruits and fruit yield. Root dry weight, shoot dry weight (21 MAP) and leaf area were also the highest in V3. 168 Among the different planting materials, air layers produced taller plants with greater plant spread (at 15, 18, and 21 MAP), number of leaves per plant, leaf area and root-to-shoot ratio (at 21 MAP). In addition, they exhibited early flowering, longest flowering duration and the shortest number of days from flowering to harvest. The number of fruits, fruit weight, fruit length, diameter and fruit yield were also observed to be the highest in air layers. Grafts (P3) recorded the highest values for stem girth, primary branch girth, root dry weight and shoot dry weight. The fruits were analysed for quality parameters, including TSS, total sugar, reducing sugar, ascorbic acid, total antioxidant activity and total carotenoids. Container size, type, and planting material showed a significant difference in ascorbic acid and carotenoid content, whereas all other parameters were non-significant. Ascorbic acid and carotenoid content were higher in airpots. In terms of container volume, the 80 L containers showed higher ascorbic acid(227.67 mg 100g-1) and carotenoid levels (0.67 mg 100g-1) , while, among planting materials, air-layered plants had the highest values. Leaf tissue was analysed for physiological and biochemical parameters viz., chlorophyll content, total carotenoids, total reducing sugars and total soluble proteins at 18 MAP. Container type and planting material did not show any significant effect on these parameters, while 80 L container volume showed significantly higher total soluble proteins compared to 40 and 60 litres. The two factor interaction between container type and size (C x V), showed that 80 L plastic containers (C1V3) recorded significantly higher plant spread (E-W and N-S), stem girth, leaves per plant, leaf area and root dry weight. The shoot dry weight was higher in both plastic container and air-pots with 80 L (C1V3 and C2V3). Air-pots with 80 L (C2V3), exhibited early flowering with more fruits per plant, enhanced flowering duration, earlier flowering to harvest and the highest fruit weight, length, diameter and fruit yield. Interaction between container type and planting material (C x P) also confirms similar results in air-pots with air layers (C2P1). Root : shoot ratio was the highest in air-pots with grafted plants (C2P3). The two factor interaction between container size and planting material (V x P) showed that air layers grown in 80 L containers (V3P1) outperformed other combinations with respect to plant height, plant 169 spread, leaves per plant, leaf area, number of fruits, flowering duration, days to flowering, days from flowering to harvest, fruit weight, length, diameter and fruit yield. Shoot dry weight, stem girth and primary stem girth were the highest in 80 L with graft (V3P3). In three factor interaction, 80 L plastic containers with graft (C1V3P3) showed higher root dry weight and shoot dry weight while plant height and leaf area were the highest for air layers in 80 L plastic container (C1V3P1). The least number of days to flowering and days from flowering to harvest were observed in 80 L airpots with air layers (C2V3P1) they also produced the highest number of leaves and fruits, as well as the greatest fruit weight, length, diameter and fruit yield. Another notable feature observed in the study is the presence of root coiling in plastic containers of all sizes (40, 60, and 80 L), regardless of the type of planting material. In contrast, root coiling was absent in airpots of all container sizes. This study underscores the importance of selecting appropriate container types, sizes, and planting materials for successful guava cultivation in containers. Airpots outperformed plastic containers by enhancing reproductive traits like early flowering, extended flowering duration, and superior fruit yield and quality. Larger containers (80 L) showed the best results across growth, fruit yield and biochemical parameters, including ascorbic acid and carotenoids. Among planting materials, air layers excelled in vegetative growth, earliness in flowering, and fruit quality, establishing 80 L airpots with air layers as the optimal choice for container-based guava cultivation. The experiment 2 entitled “Varietal evaluation of guava (Psidium guajava L.) for urban horticulture” was laid out in Completely Randomized Design (CRD) with 5 treatments and 3 replications. The treatments included five varieties of air layered guava: T1-Allahabad Safeda, T2-Lucknow 49, T3-Arka Kiran, T4-Arka Rashmi and T5- Arka Mridula. (Note: The best container type, container size and planting material (Airpots 80 L air layers) was selected from the result of first year observations of the experiment entitled “Performance evaluation of guava (Psidium guajava L.) in container and used in this experiment). T5-Arka Mridula registered the highest plant 170 height, primary and the secondary stem girth, while early flowering with highest number of flowers was registered in T4-Arka Rashmi. Leaf tissue was analysed for physiological and biochemical parameters viz., chlorophyll content, total carotenoids, total reducing sugars and total soluble proteins at 6 MAP. Total chlorophyll (0.98 mg 100 g -1), reducing sugar (1.84%) and carotenoid content(0.70 mg 100 g -1) were the highest in T5-Arka Mridula and total soluble protein was the highest in T1-Allahabad Safeda. This study emphases the importance of the growth response of different varieties of guava in containers. Among vegetative parameters, plant height, primary and secondary stem girth were the highest in Arka Mridula which was reflected in physiological and biochemical parameters like chlorophyll, reducing sugar and carotenoid contents that gave the highest values. However, in plant spread and flowering parameters like days to flowering and number of flowers the highest values were in Arka Rashmi. Plants with a compact canopy and good reproductive parameters are ideal for container growing. Thus, the present study unveils the suitability of Arka Rashmi for container growing of guava.
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    Characterization and management of fungal pathogens associated with postharvest fruit rot of Guava (Psidium guajava L.)
    (Department of Plant Pathology,Vellanikkara, 2025-03-22) Parvathi, S N; Anju, C; Seeja Thomachan Panjikkaran
    Guava (Psidium guajava L.) is one of the important commercial fruits that belongs to family Myrtaceae and is also known as “The Poor man’s Apple” or “Apple of Tropics”. It is native to tropical America and is now widespread in many tropical and subtropical countries. Being a delicious and nutritious fruit, guava is consumed directly or processed into several products such as jam, jelly, cheese, RTS beverages, etc. But, the incidence of postharvest diseases impairs the fruit quality, colour, taste and shelf life. Among the various postharvest diseases affecting the fruit, latent infections are presumed to be the origin of many rots that develop on maturing fruits. Hence this study was envisaged to document the postharvest fruit rot diseases caused by latent fungal infections, characterize the pathogens causing these diseases, and to exploit the antimicrobial compounds for developing management strategies for the major pathogen inciting the diseases. Purposive random sampling surveys were conducted in markets and homesteads of Thrissur (AEU 10), Palakkad (AEU 10 and AEU 23), and Ernakulam (AEU 9 and AEU 12) districts of Kerala. From the 19 different surveyed locations, 55 fruit samples were collected and brought to the laboratory. They were then surface-sterilized, and incubated at room temperature for disease development. A total of 36 fruit samples produced symptoms within three to twelve days of incubation including stylar end rot, soft rot, dry fruit rot, and brown to dark brown sunken lesions. The per cent disease incidence (PDI) of various diseases ranged from 16.6 to 75 per cent in the fruits sampled from various locations. The major pathogens isolated from diseased fruit samples were Lasiodiplodia and Colletotrichum. Lasiodiplodia sp. (13) was isolated from fruits exhibited stylar end rot, soft rot and dry rot. The PDS of Lasiodiplodia fruit rot varied between 13.3 to 50 per cent and the highest PDS (50 %) was recorded for fruits collected from Perumbavoor/ AEU 9, Chalakudy/ AEU 10, and Nellimolam/ AEU 12. Colletotrichum sp. (12) was isolated from brown to dark brown sunken lesions. The PDS of anthracnose ranged from 10 to 40 per cent with the highest PDS (40 %) was recorded from Kodakara/ AEU 10. Neofusicoccum sp. (2) was isolated from dry fruit rot developed near stylar end of the fruit, in the fruits sampled from Mannuthy/ AEU 10 and Kottappady/ AEU 12. Alternaria sp. (4) and Pestalotiopsis sp. (2) were isolated from brown lesions and rot developed on fruits sampled from Thrissur district. The lowest PDS (3.3 %) was recorded for fruit rot caused by Pestalotiopsis sp. Molecular characterization of six selected pathogen isolates was attempted by sequencing and analyzing the ITS or beta tubulin sequences. Based on this, the fungal pathogens associated with postharvest fruit rot were identified as Lasiodiplodia theobromae (TSG 2), Colletotrichum gloeosporioides (TKG 2), Alternaria alternata (TSG 1), Pseudopestalotiopsis camelliae sinensis (TMG 2), Neofusicoccum parvum (TMG 5), and Diaporthe phoenicicola (TPG 1). The in vitro efficacy of antimicrobial compounds viz., chitosan, hydrogen peroxide (H₂O₂), and methyl jasmonate (MeJA) was studied against selected pathogens L. theobromae (TSG 2), N. parvum (TMG 5), and C. gloeosporioides (TKG 2) using the poisoned food technique. The results showed that chitosan (2 %), H₂O₂ (2 %), and MeJA (0.1 %) consistently exhibited 100 % inhibition of all the selected pathogens. The standardization of antimicrobial treatments for managing fruit rot caused by L. theobromae (TSG 2) involved treatment of pathogen inoculated fruits with chitosan (2 %), H₂O₂ (2 %), and MeJA (0.1 %) for one min or two min duration. All the treatments reduced disease development. The treatment of fruits with chitosan (2 %) for two min was the most effective, showing slower lesion development, reduced physiological loss in weight (PLW) (2 %), and reduced respiration rates (73 ml CO2 kg-1 h-1). The subsequent effective antimicrobial compound was MeJA (0.1 %). MeJA treatment for two min, showed reduced lesion development, PLW (2.65 %) and respiration rates (101 ml CO2 kg-1 h-1). Hot water fruit dip treatment was also standardized. The treatment of fruits at 47 °C for 20 min emerged as the most promising treatment for managing fruit rot. It provided effective disease control, minimized PLW (2.38 %), and reduced respiration rate (95 ml CO2 kg-1 h-1) without causing significant browning. Evaluation of the efficacy of combined treatments of hot water and antimicrobial compounds was carried out in L. theobromae (TSG 2) inoculated fruits to select the best promising treatment. Hot water treatment at 47 °C for 20 min followed by treatment with chitosan (2 %) or MeJA (0.1 %) for 2 min completely inhibited pathogen growth, reduced PLW (2.36 % and 2.43 % respectively) and respiration rates (65 and 93 ml CO2 kg-1 h-1 respectively) of fruits, thus demonstrated their superiority to individual treatments.