Growth, yield, and fruit quality of tomato as influenced by the application of seaweed extract under water-deficit stress | |
| Author | Ahmed, Mostak |
| Call Number | AIT Diss no.AS-23-01 |
| Subject(s) | Plants--Effect of stress on Plants--Drought tolerance Tomatoes |
| Note | A Dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Agricultural Systems and Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Global population is projected to reach almost 10 billion by 2050; hence, agricultural production will need to be doubled to feed this fast-growing population. Water-deficit stress has significantly negative effects on crop yields, and it is a major impediment in achieving long-term global food and nutrition security. Water-deficit stress is mostly caused by climate change and improper management of agricultural land. Tomato (Solanum lycopersicum L.) plants under both open-field and protected cultivation systems often encounter drought stress. Tomato is a popular vegetable crop for its flavor, sweetness, nutritional value, and health benefits. It is grown in a variety of environments, including open-air fields and greenhouses, where they are subjected to different biotic and abiotic stresses during the cultivation process. Water-deficit stress is one of the most important abiotic stresses that can reduce tomato yield by as much as 50%. Higher susceptibility of tomato to water-deficit stress demands for the development of management strategies that can maintain or enhance its productivity under limited irrigation water availability. In order to increase crop tolerance against drought stress, maximize crop yield and water productivity, and ensure sustainable tomato production, the application of exogenous plant biostimulant and nutrient management, and adoption of efficient water management strategies need to be integrated with the existing cultivation practices. Therefore, an interactive effect of biostimulant application, nutrient management, and irrigation water regime was investigated on tomato using several polyhouse experiments.In the first polyhouse experiment, two independent pot experiments were conducted to find out the best soil drench or foliar spray dose of a commercial Ascophyllum nodosum seaweed extract (ASE) formulation (Amino Seaweed, SV Group, Bangkok, Thailand) on growth, physiological and biochemical parameters, fruit yield, quality, and water productivity of tomato under water-deficit stress. The commercial ASE formulation was applied in five doses (0, 2.5, 5, 10, and 20 mL L−1 ) as a soil drench (Experiment 1) or as a foliar spray (Experiment 2) under three soil moisture levels (50, 75, and 100% field capacity [FC]). Severe soil moisture deficit of 50% FC caused a 67 and 52% reduction in fruit yield, 11 and 11% reduction in fruit length, 25 and 29% decrease in leaf relative water content, while total soluble solids content was increased by 38 and 49% compared with 100% FC in Experiments 1 and 2, respectively. Soil drench or foliar spray of the commercial ASE formulation at 5 mL L−1 was effective at all soil moisture levels. Soil drench of the commercial ASE formulation at 5 mL L−1 resulted in 225% higher fruit yield in comparison to the untreated plants at 50% FC, whereas its application as a foliar spray resulted in 271% higher fruit yield in comparison to the untreated plants subjected to severe water-deficit stress (50% FC). Water productivity was found lower for the untreated plants regardless of soil moisture levels in both application methods; however, it was maximized at 5 mL L–1 for all soil moisture levels. The beneficial effects of 5 mL L–1 ASE formulation dose was also evident in physiological/biochemical traits and fruit quality of tomato regardless of application methods. Tomato yielded more when the commercial ASE formulation was applied at 5 mL L–1 as a soil drench (523.3 g plant–1 fruit yield) rather than as a foliar spray treatment (397.1 g plant–1 fruit yield). The results indicate that (i) 5 mL L−1 could be regarded as an optimum dose of the commercial ASE formulation for tomato applied either as a soil drench or foliar spray and (ii) exogenous application of the commercial ASE formulation at 5 mL L−1 as a soil drench treatment is more efficient, especially in fruit yield improvement, compared with its application as a foliar spray and, therefore, this technique holds promise for tomato cultivation under moderate water-deficit stress.In the second polyhouse experiment, one study was conducted to assess the combined effects of ASE and silicon (Si) on growth, fruit yield, fruit quality, and water productivity of tomato under water stress. Five doses of ASE (0, 1.25, 2.5, 3.75, and 5 mL L−1 ) were applied in combination with 60 kg ha−1 soluble Si in the form of monosilicic acid (as soil incorporation regardless of ASE doses) along with a control (where no ASE or Si was applied) under three soil moisture regimes of 50%, 75%, and 100% FC. Data on growth, fruit yield, water productivity, fruit quality, and physio biochemical parameters of tomato were collected. The results revealed that severe water stress of 50% FC negatively affected growth, physiological traits, and fruit yield of tomato (43–80% lower yield across ASE doses) compared with those at 100% FC, whereas fruit quality parameters (total soluble solids, fruit firmness, color index, and fruit pH) increased with reduced soil moisture regime. Application of ASE at 3.75 and 5 mL L−1 in combination with soluble Si at 60 kg ha−1 resulted in statistically similar fruit yields under a sufficient soil moisture level of 100% FC and a moderate soil moisture level of 75% FC, respectively. A consistent trend of higher fruit yield and water productivity was observed for plants supplemented with 5 mL L−1 ASE and 60 kg ha−1 soluble Si regardless of soil moisture regimes. Similarly, individual Si supplementation at 60 kg ha−1 was also effective and caused 207% increase in fruit yield even at severe water stress of 50% FC compared with the control. However, a combined application of ASE and Si had more promising results than the sole application of Si. Exogenous soil application of ASE at 5 mL L−1 along with soluble Si at 60 kg ha−1 holds promise for tomato production under moderate to sufficient soil moisture availability.The third polyhouse experiment was conducted to evaluate the combined effects of ASE and potassium (K) on tomato under water-deficit stress. The commercial ASE was applied in five doses (0, 1.25, 2.5, 3.75, and 5 mL L–1 ) along with 100 kg K2O ha–1 under three soil moisture levels (50%, 75%, and 100% FC). The control plants did not receive any application of ASE or K, while only K applied in the same dose (100 kg K2O ha–1 ) without ASE was also included as a treatment. Data were acquired on tomato growth, fruit yield and quality, and physio-biochemical parameters. A consistent trend of poor vegetative growth, fruit yield, and physiological responses at deceasing soil moisture level was observed regardless of ASE doses where leaf area, root dry matter, fruit yield, water productivity, and membrane stability index were reduced in the range of 26–55%, 42–58%, 53–72%, 27–48%, and 37–57%, respectively, at 50% FC compared with those at 100% FC across ASE doses. Decreasing soil moisture level at 50% FC caused up to 50% increase in fruit firmness and 33–67% increase in electrolyte leakage compared with those at 100% FC across ASE doses. Application of ASE in combination with K was effective in all doses and the highest dose of 5 mL L–1 was the most effective, which resulted in an increase of 119–266% in fruit yield, 115–178% in water productivity, 26–60% in leaf relative water content, and 61–125% in membrane stability index across soil moisture levels compared with the control plants. The same dose reduced electrolyte leakage of plants by 26–48% compared with the control plants across soil moisture levels. Sole application of K was also effective and caused a significant increase in growth, fruit yield, and physiological parameters of tomato in comparison to the control plants. Fruit yield of plants supplemented with 5 mL L–1 of ASE in combination with 100 kg K2O ha–1 at 50% FC was statistically similar with the fruit yield of control plants at 100% FC, while water productivity was even higher for the same treatment combinations. The same was also largely true for other growth and physiological parameters highlighting the benefits of the integrated application of ASE and K in alleviating the detrimental effects of drought stress on tomato. An integrated application of ASE at 5 mL L–1 along with 100 kg K2O ha–1 is recommended to grow tomato in water-scarce environments. |
| Year | 2023 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural Systems and Engineering (ASE) |
| Chairperson(s) | Datta, Avishek; |
| Examination Committee(s) | Salin, Krishna R.;Tsusaka, Takuji W.; |
| Scholarship Donor(s) | National Agricultural Technology Program (NATP), Bangladesh Agricultural Research Council, Bangladesh; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2023 |