Ph.D

The experiment entitled “Hydroponic production of tomato (Solanum lycopersicum L.)” was conducted at the Instructional Farm, College of Agriculture, Vellayani, during 2021-2023 to evaluate hydroponic systems for tomato cultivation, standardize nutrient solutions and examine the effects of magnetized solution on growth and yield of tomato. The field experiments were conducted in two parts. The first experiment was framed to identify the best method of hydroponics for tomato during February-June 2022. It was laid out in a completely randomised design (CRD) with seven treatments and three replications. The treatments were T1: Nutrient film technique (NFT), T2: Deep flow technique (DFT), T3: Ebb and flow system, T4: Deep water culture (DWC), T5: Drip system, T6: Wick system and T7: Control (soil cultivation). The growth parameters, viz., plant height, number of leaves per plant, leaf area per plant, number of branches per plant, stem girth and dry matter production (DMP) were significantly influenced by methods of hydroponics. Among the treatments, T7 produced taller plants at the harvest stage, which was on par with T3. However, the number of leaves and stem girth were found to be significantly higher in T3 during the harvest stage. Similarly, at 60 days after transplanting (DAT), T3 recorded higher leaf area and chlorophyll content. At the harvest stage, the number of branches and DMP were the highest in T3. Earliness in flowering was observed in T3, which was on par with T6, while the first fruit development and first harvest were recorded in T3. During 40-60 DAT, T3 resulted in the highest crop growth rate (CGR) which was on par with T1, and during 20-40 DAT, T3 resulted in the highest relative growth rate (RGR) which was on par with T6, respectively. Longer fruits were produced in T3, which was on par with T6 and T4. Whereas, the higher fruit diameter recorded from T3 was on par with T6 and T5. Similarly, T3 recorded higher average fruit weight with 45 per cent increment in total fruit number compared to the soil cultivation. The highest fruit yield per plant was also observed in T3 (2.10 kg), while T7 (0.99 kg), recorded the lowest fruit yield per plant. Significantly higher quality attributes including total soluble solids (TSS) and ascorbic acid contentwere noticed in T3, which was on par with T6. Among the root parameters, greater root length was observed in T6, which was on par with T3, which also recorded higher root volume and root weight. The N, P and K uptake was also found to be the highest in T3, which was significantly the lowest in T7. Also, the treatment T3 recorded comparatively higher net income (₹ 7761 per 40 m2) and B:C ratio (1.53). The second experiment was carried out to evaluate the influence of nutrient solutions and magnetic effect on growth and yield of tomato during two seasons of 2022-2023. The experiment was laid out in CRD with two factors. Treatments were comprised of two states of nutrient solutions, viz., normal (I1) and magnetized with 2000 G (I2), and five different nutrient solutions, viz., Hoagland solution (S1), Cooper’s solution (S2), Benoit’s solution (S3), solution from Agcaoili (2019) (S4) and solution from Jaenaksorn and Ikeda (2004) (S5), with three replications. Magnetization of nutrient solution had a significant influence on growth parameters. Taller plants were observed in I2 with higher number of leaves and branches with the greatest leaf area, DMP and stem girth during the harvest stage of both the seasons. Among different nutrient solutions, S3 recorded taller plants with a higher number of leaves and leaf area during both the seasons. At 60 DAT, the higher leaf area produced by S3 was on par with S2 during both seasons. Similarly, the number of branches and DMP were higher in S3, which produced a comparable number of branches with S2 during the harvest stage of both seasons. Higher stem girth produced in S3 was on par with the remaining treatments except for S4 during both seasons. Earlier flowering, fruiting and harvesting were recorded in I2, and the same were significantly delayed in I1. Among different nutrient solutions, S3 had significantly earlier production of flowers, which was on par with S2 and S1 during both seasons. However, the flower development was significantly influenced by the treatments only during the first season, and S3 had earlier fruit development, which was on par with all other treatments except S4. During both seasons, the first harvest was recorded in S3 which was on par with S2. LAI was found to be highest in I2 at the harvest stage of both seasons. Plants in S3 recorded higher LAI, which was on par with S2 during both seasons. At 60 DAT, during both seasons, I2 recorded more chlorophyll content than I1. And, during both seasons, S3 had higher chlorophyll content, which was on par with S2 only in the first season. During both seasons, I2 resulted in the highest CGR and RGR at 40-60 DAT and 20-40 DAT, respectively. Among the nutrient solutions, S3 resulted in higher CGR and RGR, during both seasons, and was on par with S2 with respect to only CGR. During both seasons, greater number of fruits, fruit weight and yield were recorded from I2. Also, among different nutrient solutions, S3 produced higher number of fruits which was on par with S2 and S1 during the first season. The highest fruit weight was obtained from S3, and also the higher yield recorded from S3 was on par with S2 during both seasons. TSS and ascorbic acid content also varied significantly during both seasons, with I2 recording a significantly higher value. Among nutrient solutions, S3 had more TSS and ascorbic acid compared to other treatments. Root parameters and nutrient uptake were also significantly influenced by the magnetized treatment during both seasons. With respect to the nutrient solutions tested, S3 recorded significantly higher root length and root volume, which was on par with S1 and S5 during both seasons. However, the plants in S3 recorded higher root weight, which was comparable with the remaining treatments except for S4 in the first season. During both seasons, N, P and K uptake was found to be the highest in S3, while the lower value was recorded in S4. The treatment combination of Benoit’s solution with magnetic effect (i2s3) consistently demonstrated superior performance, including increased plant height at 20 DAT in the first season, a greater number of leaves at 60 DAT, and a higher number of branches at both 60 DAT in the second season and at harvest in the first season. Additionally, i2s3 induced earlier flowering in the first season and led to earlier harvests in both seasons. This treatment also resulted in higher fruit weight across both seasons, comparable to i2s2 in the first season, and achieved greater fruit diameter during the first season. Nutrient uptake of N, P and K was maximized under i2s3 in both seasons. However, application of Cooper’s solution with magnetic effect (i2s2) yielded higher net income and a B:C ratio across both seasons (1.49 and 1.74 respectively). From the results of the study, it could be concluded that among various hydroponic methods, the ebb and flow system proved most effective for tomato cultivation. Utilizing Benoit's nutrient solution, comprising KNO₃, Ca(NO₃)₂•4H₂O, KH₂PO₄, MgSO₄•7H₂O, MnSO₄•7H₂O, H₃BO₃, ZnSO₄•7H₂O, CuSO₄•7H₂O, Na₂MoO₄, and Fe-EDDHA, significantly improved the growth and yield characteristics of tomato. The application of a magnetic field (2000 G) further enhanced the growth and yield of tomato in the hydroponic system.