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Development of seedless watermelon (Citrullus lanatus (Thunb. Matsum. &Nakai) with improved fruit quality
(College of Agriculture, Vellanikkara, 2025-12-17) Ansaba, V; Pradeep Kumar T
Watermelon (Citrullus lanatus) is a globally important cucurbitaceous crop valued for its sweet taste and nutritional content. Traditional diploid varieties contain numerous hard seeds that reduce consumer appeal, leading to the development of seedless watermelons through triploid breeding. Seedless types are increasingly popular due to their convenience and enhanced nutritional qualities, including higher levels of lycopene, β-carotene, citrulline, and vitamin C. They are widely preferred in domestic and international markets, often commanding a price premium. However, existing triploid seedless watermelon hybrids very often produce fruits with low TSS, false seeds, and hollow heart, which affects the quality. In this context, the present study, entitled “Development of seedless watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) with improved fruit quality,” was undertaken to develop superior quality triploid seedless watermelon hybrids and to assess the potential of diploid male lines in the development of triploid hybrids with improved fruit quality. The research work was carried out in three experiments, viz., introduction and evaluation of watermelon germplasm, development of triploid hybrids, and evaluation of F1 hybrids in the experimental field of the Department of Vegetable Science, College of Agriculture, Kerala Agricultural University, Vellanikkara, Thrissur, over three consecutive years (2022 – 2025), from November to March. In the first experiment, thirty-eight watermelon genotypes collected from different parts of the country were evaluated for various biometric, qualitative, and biochemical traits to identify genotypes with superior quality, yield, and earliness. Analysis of variance revealed that all the characters studied exhibited significant variation among the genotypes. The narrow gap between phenotypic and genotypic coefficient of variation (PCV and GCV) indicated that variability was mainly genetic, making the traits amenable to effective direct selection. High heritability coupled with moderate to high genetic advance as per cent of the mean (GAM) was observed for all traits, except days to first harvest and crop duration, indicating the predominance of additive gene action. Yield per plant showed significant positive correlations with fruit polar diameter (0.690), average fruit weight (0.639), length of main vine (0.473), duration of crop (0.388), fruits per plant (0.380), and fruit equatorial diameter (0.377), while it showed significant negative correlations with days to first male flower anthesis (-0.570), days to first female flower anthesis (-0.465), and node at which first female flower emerged (-0.349). Path analysis revealed that duration of the crop (0.339) had the highest direct positive effect on yield per plant, followed by fruit polar diameter (0.289), average fruit weight (0.195), fruit equatorial diameter (0.189), fruits per plant (0.132), and length of main vine (0.0.067). Twenty superior diploid watermelon genotypes were identified through cumulative scoring for yield and quality traits, including TSS, total sugars, pulp firmness, Vitamin C, citrulline, earliness, and yield per plant. The lines, such as AHW/BR-22 (T21), CL-17 (T12), Arka Shyama (T1), AHW/BR-43 (T27), Crimson Sweet (T10), Arka Manik (T4), CL-19 (T14), CL-9 (T30), CL-12 (T33), Arka Muthu (T8), CL-8 (T29), AHW/BR-40 (T26), CL-14 (T35), CL-10 (T31), AHW/BR-37 (T25), AHW/BR-25 (T23), CL-12 (T32), Asahi Yamato (T6), CL-7 (T28), and CL-6 (T11), showed desirable combinations of quality and productivity and were identified as promising male parents for triploid hybrid development. In the second experiment, the identified diploid parents were crossed with the stable tetraploid female line, KAU-CL-TETRA-1, developed by Kerala Agricultural University in a top cross fashion. The highest fruit set percentage (85 %) and number of seeds per fruit (291.60) were observed in the top cross C9 (KAU-CL-TETRA-1 × CL-17). In the third experiment, twenty newly developed triploid F1 hybrids, along with two standard checks (Shonima and Swarna) and all the parental lines (the tetraploid female line, KAU-CL-TETRA-1, and the diploid male lines of hybrids and checks) used in the breeding programme, were evaluated in a Randomized Block Design (RBD) with three replications. Analysis of variance revealed significant differences among the F1 hybrids and parents for all the biometric and biochemical traits observed. The analysis of general combining ability (GCA) effects for biometric and biochemical traits revealed significant variation among parental genotypes. The diploid lines Arka Shyama, CL-17, AHW/BR-22, AHW/BR-43, Arka Manik, Crimson Sweet, and Arka Muthu were identified as good general combiners for various fruit quality and yield traits. Heterosis values were estimated over mid-parent, better parent, and standard checks, Shonima and Swarna. The triploid seedless hybrids KAU-CL-TETRA-1 × Arka Shyama, KAU-CL-TETRA-1 × CL-17 (orange fleshed), KAU-CL-TETRA-1 × Arka Muthu, KAU-CL-TETRA-1 × AHW/BR-43, KAU-CL-TETRA-1 × Crimson Sweet, KAU-CL-TETRA-1 × AHW/BR-22, KAU-CL-TETRA-1 × Arka Manik, and KAU CL-TETRA-1 × AHW/BR-37 were found to have superior performance over the standard checks across multiple desirable quality traits. These hybrids also expressed low physiological abnormalities. The study also revealed that pollen parent variation significantly influenced the flesh colour expression in triploid hybrids, underscoring the paternal role in carotenoid accumulation and pigmentation. The orange and yellow colour of male parents was found to have a dominant effect on the red flesh of the tetraploid female line. Notably, the development of the first orange-fleshed seedless triploid hybrid (KAU-CL-TETRA 1 × CL–17) from the public sector in India marks a pioneering achievement. The study highlights the potential of triploid seedless watermelon hybrids in combining seedlessness with improved fruit quality and enhanced nutritional attributes. These findings lay a foundation for the commercial exploitation of hybrid vigour and emphasize the need for replicated and multilocational testing. The performance of these hybrids under protected cultivation needs to be evaluated. The potential of diploid pollinizers on these newly developed sterile triploid watermelon hybrids warrants further study.
Enhancing nutrient use efficiency in lowland rice using beneficial root endophytic fungus Piriformnospora indica
(Department of Agronomy, College of Agriculture, Vellayani, 2025-12-30) Adarsh S; Ameena M
The study entitled ‘Enhancing nutrient use efficiency in lowland rice using beneficial root endophytic fungus Piriformospora indica’ was conducted at the Department of Agronomy, College of Agriculture, Vellayani during 2019-2025. The objectives of the study were to standardise a suitable growing medium for the colonisation of P. indica in rice seedlings and to evaluate the performance of P. indica colonised rice under varying NPK levels in both pot and field conditions. The investigation comprised three experiments, each conducted using the rice variety Uma.
The first experiment on ‘Standardisation of growth media for P. indica colonisation of rice seedlings’ was conducted as a lab study at the Department of Plant Pathology to standardise a growing medium for colonisation of P. indica in rice. The experiment was laid out in completely randomized design with eight treatments replicated nine times. The treatments were: T1 [Paddy soil (PS): FYM: vermicompost (VC) in 1:1:1 (v/v) with P. indica (+Pi)], T2 [PS: FYM:VC in 1:1:1 without Pi (-Pi)], T3 [PS: FYM: neem cake(NC)in 1:1:1 + Pi], T4 [PS: FYM:NC in 1:1:1 - Pi], T5 [PS: FYM: coir pith compost (CPC) in 1:1:1 + Pi], T6 [PS: FYM: CPC in 1:1:1 - Pi], T7 [PS: FYM:VC:NC: PC in 1:1:1:1:1 + Pi] and T8 [PS:FYM:VC:NC:CPC in 1:1:1:1:1-Pi]. The sterilized medium prepared as specified, was inoculated with fungal broth (10 g mycelia per 100 g medium), and sown with surface-sterilized seeds to assess the growth and colonization. Results revealed that, T5 resulted in the highest germination percentage (92.28), dry matter production (19.12 mg per plant), vigour index-1 (1953.67), root volume (0.15 cm³ per plant), root dry weight (10.29 mg per plant), and root colonisation efficiency (92.70 %) at 14 days after sowing. Based on the growth and colonisation potential, the substrate comprising equal proportions of PS, FYM, and CPC was identified as the promising for mass colonisation of P. indica in rice seedlings. The second experiment on ‘Response of P. indica colonised rice to various NPK levels’ (pot culture) was laid out in CRD (factorial) with five nutrient levels and two types of colonization (2) replicated thrice (10 treatment combinations) with seven pots per replication. The treatments comprised of T1 [100% NPK + Pi], T2 [75% NPK+Pi], T3 [50% NPK+Pi], T4 [25% NPK+Pi], T5: [0% NPK+Pi], T6 [100% NPK–Pi], T7 [75% NPK–Pi], T8 [50% NPK–Pi], T9 [25% NPK–Pi], and T10 [0% NPK-Pi (Absolute control]. Rice was raised as per KAU POP recommendations. Colonisation at 100% NPK resulted in the tallest plants and the highest dry matter production at harvest (37.79 g per plant). However, the number of productive tillers per plant under 100% NPK + Pi was comparable to T2, which in turn was on par with 100% NPK - Pi for productive tillers, grain yield, and straw yield per plant. 100% NPK + Pi showed superior values for major root parameters. However, 75% NPK+ Pi were statistically on par with non-colonised plants at 100% NPK for root length, root volume, number of root branches, and root-shoot ratio.
Colonisation and nutrient levels had significant influence on physiological parameters of rice. Malondialdehyde (MDA) content was lower in colonized plants at 100 % NPK. However, the highest superoxide dismutase (SOD) and peroxidase were recorded in 75% NPK+ Pi and on par with 100% NPK. The soil chemical analysis revealed the significant influence of colonisation with 100% NPK + Pi recording higher available N and P and plant P uptake which were comparable to 75% NPK + Pi. The three promising nutrient levels of pot experiment viz., 100,75 and 50% NPK with and without the endophyte along with absolute controls were taken for the field experiment.
The third experiment on ‘Evaluating the field performance of P. indica colonised rice to various nutrient levels’ was laid out in RBD (factorial) with four nutrient levels and two types of colonization replicated thrice. The treatment combinations were T1 [100% NPK+Pi], T2 [75% NPK+ Pi], T3 [50% NPK+Pi], T4 [0% NPK+Pi], T5 [100% NPK–Pi], T6 [75% NPK–Pi], T7 [50% NPK–Pi], and T8 [0% NPK-Pi]. The crop of rice was raised as per KAU POP recommendations. Among the yield parameters, 100% NPK +Pi resulted in the highest yield attributes. However, performance of 75% NPK +Pi was comparable to KAU POP with respect to yield attributes at both locations. A pooled grain yield of 6.24 t ha⁻¹ was obtained with 100% NPK + Pi followed by 75% NPK + Pi (5.27 t ha⁻¹).
Regarding root parameters, root length (37.90 cm) and root dry weight (10.05 g) were superior in colonised plants at 100% NPK followed by 75% NPK+Pi at 45 DAT. Colonisation and nutrient levels had their significance on physiological parameters. The nutrient use efficiency parameters of rice were significantly influenced and Pi + 100% NPK resulted in superior agronomic efficiency (AE) of N, P and K; apparent recovery efficiency (ARE) of N and K; physiological efficiency (PE) of N and K; and partial factor productivity (PFP) of N and P for both locations. Economic analysis revealed that the net income and benefit cost ratio were the highest in 100% NPK +Pi for both locations whereas 75% NPK +Pi was profitable than 100% NPK -Pi in both locations.
The study identified a growth medium comprising equal proportions of paddy soil, farmyard manure, and coir pith compost as the most effective one for colonising P. indica in rice, based on growth and colonisation efficiency. Field evaluation of seedlings raised in this medium, supplied with NPK as per KAU POP recommendations, showed the highest overall performance in terms of growth and yield. However, the yield of colonized plants receiving 75 per cent of the recommended NPK was on par with non-colonised plants receiving full NPK. Based on the above findings, it could be inferred that P. indica colonization can facilitate 25 per cent reduction in chemical fertilizer use without compromising the productivity of transplanted lowland rice during summer.
Yield performance and stress responses of sorghum
(Department of Agronomy, College of Agriculture, Vellayani, 2025-10-23) Swathy, A H; Usha, C Thomas
Climate change has emerged as one of the most important global environment issues. Rising CO2 and temperature, changing rainfall patterns, and an increase in the frequency and duration of heat stress and water stress are all effects of climate change. Sorghum being a C4 plant with increased photosynthetic efficiency and abiotic stress tolerance, is a key crop in semi-arid tropical regions. Assessing the impact of climate change on sorghum productivity is crucial for addressing future food security challenges. This PhD project aimed to assess yield performance, response to water and heat stress in sorghum. In the first part of the project (chapter 2), twenty grain sorghum varieties were evaluated for the yield performance and variations in plant and leaf morphology. In the second part (Chapter 3), four sorghum genotypes including two grain sorghum (Sorghum bicolor ‘Farfara’ and Sorghum sudenense) and two wild sorghum (Sorghum bulbosum and Sorghum macrospermum) genotypes were grown focusing on studying the responses of these genotypes under water stress and heat stress conditions. In the third part (chapter 4), a large population of sorghum genotypes with different aquaporin alleles were grown to study the link between stomatal anatomy and kinetics and their relationship with water use efficiency under water stress. The first experiment was carried out in field conditions at College of Agriculture, Vellayani, Kerala, India. The second and third experiments were carried out in potted plants grown in the glasshouse at Hawkesbury Institute for the Environment, Western Sydney University, Australia. The first experiment revealed significant variations in growth and yield attributes among different sorghum varieties at various stages of development. CSV 17 performed exceptionally well across a variety of measures. It showed significantly higher grain yield, early flowering, and a shorter time to maturity, and higher harvest index compared to other varieties. CSV 20 demonstrated impressive economic performance, with the highest net returns per hectare and a remarkable benefit-cost ratio due to its significantly higher stover yield. In terms of leaf area index (LAI) and leaf area duration (LAD) variety CSV36 performed better. In second experiment S. bicolor ‘Farfara’ exceled in maintaining high intrinsic water use efficiency (iWUE) and quantum yield of photosystem II (ΦPSII) under water stress, while S. bulbosum excelled by maintaining carbon assimilation rate (An) and stomatal conductance (gs). In third experiment we observed a large variation in stomatal kinetics and their related dynamic water use efficiency and only stomatal opening speed (kopen) was found to be affected by water stress among other stomatal traits. The results of this research will provide valuable data for breeding programs focused on creating new sorghum varieties
Climate change impact on operation policy and performance indices of a reservoir using machine learning techniques
(Department of Soil and Water Conservation Engineering Kelappaji College of Agricultural Engineering and Technology, 2025-11-22) Vinnakota Yesubabu; Anu Varughese
Water resource systems play a major role in human wellbeing. The hydrologic changes resulting from climate change will affect the planning, design, and operation of water resource systems. Developing water schemes based on present conditions without considering possible future changes could increase water resource pressure in the future period. Therefore, it is of utmost importance to consider these changes in the future design and management of water supply systems. To comprehend the impact of climate change on water resource management, a comprehensive modelling framework that considered both hydrological responses and reservoir operation was indispensable. In this regard, Malampuzha reservoir system in Palakkad district of Kerala was selected to evaluate the impact of climate change on reservoir and its performance.
To select the suitable climate model for the study, the performance of 15 CMIP6 GCMs in precipitation, maximum and minimum temperature was compared to the observed data of Malampuzha for the period 1990-2014 with the help of Compromise Programming (CP) that involves metrics such as R2, PBIAS, NSE and NRMSE. The results of the CP analyses of the statistical metrics suggests that CNRM-CN6-1 model for precipitation and MRI-ESM2-0 model for maximum and minimum temperature are the suitable models for Malampuzha region. Different bias correction techniques were applied to improve the raw predictions of GCMs. Power Transformation (PT) for precipitation and Variance Scaling (VS) technique for temperature has shown superiority over other techniques. Three future scenarios were considered in this study from CMIP6 Shared Socioeconomic Pathways (SSP126, SSP245 and SSP585). Selected bias correction techniques were applied to the future period to get bias corrected future climate variables.
Rainfall-runoff modelling was chosen to predict reservoir inflow. Three hydrological models (IHACRES, SWAT and HECHMS) and Machine Learning (ML) models such as ANN, SVM, RF, and Wavelet coupled models were compared and Wavelet coupled RF (WRF) model was selected because of its greater accuracy and was used to simulate future reservoir inflow under different SSPs. CROPWAT model was used to estimate the irrigation water requirement for baseline and future periods. Land use change analysis of Malampuzha reservoir command area was done with the help of MOLUSE plugin of QGIS. Optimization program was developed by considering all the necessary constraints with the objective of minimizing squared relative deficiency in water allocation. Optimal water allocation was derived from the developed optimization technique using genetic algorithm for baseline and future periods. Reservoir performance indices such as Reliability, Vulnerability, resiliency and sustainability were calculated and compared for both timelines. Climate change impact on reservoir performance is evaluated.
Selected GCM models predicted an increase in average annual maximum temperature (from 0.23oC in near future to 3.26oC in far future), an increase in average annual minimum temperature (from 0.62oC in near future to 3.12oC in far future) and decrease in average annual precipitation (2.73% in near future to 10.89% in far future) in the future compared with the base period. The LULC changes indicate a shift towards urbanization and plantation expansion, with a concurrent decline in agricultural lands (2425 ha (14%) reduction by the end of the century) and water bodies. Because of an increase in crop water demand of 11.7% and decrease in reservoir inflow of 27.3%, the amount of water allocation under optimal reservoir management conditions was less than the demand. The command area water demand will not be met by the reservoir for far futures of SSP245 and SSP585 scenarios because of more increase in temperature (3.26oC) and erratic behavior of precipitation which indicates the impact of climate change. A suitable optimization technique using genetic algorithm was developed which can be used for deriving the best operation policy for the Malampuzha reservoir in future. The observed decline in reliability and resiliency along with a notable increase in vulnerability from 0.028% to 9.47%, emphasizes the substantial challenges that climate change imposes on reservoir operation. These findings highlight the urgent requirement of climate-resilient management strategies to ensure the long-term sustainability of reservoir in the far future.
Development of micropropagation protocols for aquascape plants
(Department of Floriculture and Landscaping, College of Agriculture, Vellayani, 2025-05-30) Greeshma Baby; Rafeekher, M
The thesis work entitled “Development of micropropagation protocols for aquascape plants” was carried out at Department of Floriculture and Landscaping, College of Agriculture, Vellayani during 2022-2024. The study was conducted to standardize in vitro propagation protocol for three aquascape plants Hydrocotyle verticillata, Rotala wallichii, and Echinodorus grisebachii using stem node explants. The study comprised of five experiments. The first experiment was to standardize surface sterilization of explants; explants of three plants were separately treated with mercuric chloride in concentrations (0.08 %, 0.1 %) for durations (5 minutes, 7 minutes), mercuric chloride (0.03 %, 0.05 %) for durations (5 minutes) and sodium hypochlorite (1 %, 1.5 %) for durations (10 minutes, 15 minutes). The experiment was laid out in completely randomized design consisting of eleven treatment combinations along with control (distilled water) with three replications and carried out separately for three plants. In Hydrocotyle verticillata 0.08% HgCl₂ for 7 minutes was the best treatment resulted in maximum survival with no contamination. In Rotala wallichii 0.03 % HgCl₂, 5 minutes was most effective with no contamination and maximum survival. In Echinodorus grisebachii 0.05 % HgCl₂, 5 minutes was the best surface sterilization treatment with maximum survival and no contamination. The second experiment was to standardize tissue culture medium for culture establishment and shoot induction. The explants were inoculated in Murashige and Skoog (MS) medium and half-strength Murashige and Skoog (1/2 MS) medium, with different combinations of growth regulators, namely BAP (0, 0.2, 0.5, 1.0, 1.5, 2.0) mg L⁻¹, NAA (0.2, 0.5, 1.0, 1.5) mg L⁻¹, and Kinetin (0, 1, 3, 5) mg L⁻¹. The experiment was laid out in completely randomized design with twenty-six treatment combinations and three replications. In Hydrocotyle verticillata, MS +1.5 mg L-1 BAP was found to be the best in all shoot initiation parameters. MS + 2 mg L-1 BAP was found to be best shoot initiation medium in Rotala wallichii and Echinodorus grisebachii. Third experiment was to standardize the rooting medium. Explants were inoculated in different combinations of IBA (0, 1, 3, 5) mg L-1 and IAA (0, 0.5, 1, 1.5) mg L-1. The experiment was laid out in completely randomized design with fourteen treatment combinations and three replications. The Best rooting medium in Hydrocotyle verticillata and Rotala wallichii was ½ MS + 1.0 mg L-1IBA with maximum root initiation percentage and rapid root emergence. In Echinodorus grisebachii ½ MS + 3.0 mg L-1 IBA was the best. Fourth experiment was to standardize sucrose concentration for both shooting and rooting medium. The experiment was laid out in completely randomized design with eight treatments each for shooting and rooting medium. Explants were inoculated in best shooting and rooting medium along with different sucrose concentrations (10, 20, and 30) g L-1. For Hydrocotyle verticillata, among various sucrose concentrations tested, 1.5 mg L-1 BAP medium along with 30 g L-1sucrose was found to be most effective for enhancing all vegetative attributes, including shoot initiation, elongation, and leaf production. Additionally, the best rooting response was achieved in half strength MS with 1 mg L-1IBA and 30 g L 1sucrose, resulted in maximum root initiation. The combination of 30 g L-1sucrose with MS medium containing 2 mg L-1 BAP was the most effective for promoting shoot initiation, elongation, and leaf formation in Rotala wallichii and maximum root initiation was obtained in half strength MS medium with 1 mg L-1 IBA and 30 g L-1 sucrose. In Echinodorus grisebachii, supplementation of MS medium with 2 mg L-1 BAP and 30 g L-1 sucrose significantly enhanced shoot initiation, elongation, and leaf production and maximum rooting response was observed in half-strength MS medium enriched with 3 mg L-1 IBA and 30 g L 1sucrose. The fifth experiment was to standardize hardening medium. Soil, aqua soil, LECA pebbles, sand, gravel and coco fiber were used in this experiment. These substrates were filled in net pots and kept inside containers filled with water for hardening. The experiment was laid out in completely randomized design consisting of eight treatments with five replications. Among these aqua soil proved to be the most effective medium for hardening in all three plants. The protocols for Hydrocotyle verticillata, Rotala wallichii, and Echinodorus grisebachii were standardized. For Hydrocotyle verticillata, the shoot initiation medium was 1.5 mg L-1 BAP, rooting with ½ MS + 1.0 mg L-1 IBA, 30 g L-1 sucrose, and aqua soil as the hardening substrate. In Rotala wallichii, 2 mg L-1 BAP for shoot initiation, rooting with ½ MS + 1.0 mg L-1 IBA, 30 g L-1 sucrose, and aqua soil for hardening. For Echinodorus grisebachii, shoot initiation medium was 2 mg L-1 BAP, rooting with ½ MS + 3.0 mg L-1 IBA, 30 g L-1 sucrose, and aqua soil as the substrate for hardening.