Effects of silicon application on growth, physiological parameters and grain yield of maize under water-deficit stress | |
| Author | Napat Sirisuntornlak |
| Call Number | AIT Diss no.AS-19-03 |
| Subject(s) | Corn--Effect of drought on Corn--Drought tolerance Silicon in agriculture Seed treatment |
| 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 | Silicon (Si) has been known to enhance plant tolerance against biotic and abiotic stresses besides its beneficial effects on plant growth and yield. Two polyhouse experiments were conducted to evaluate the effect of Si against water-deficit stress in maize (Zea mays L.) applied through seed priming and soil incorporation methods, and to find out the optimum dose of Si under each method. In the seed priming experiment, seeds were exposed to different Si levels, up to 2 mM (0, 0.25, 0.5, 1, 1.5, and 2 mM), germinating under three soil moisture regimes (100%, 75%, and 50% field capacity [FC]). In the soil incorporation study, the treatments included were six Si doses from 0 to 600 (0, 37.5, 75, 150, 300, and 600 kg ha–1 ) kg ha–1 under the same soil moisture regimes. Grain yield was reduced by 59% and 69% in the seed priming and soil incorporation study, respectively, at 50% FC. Si application was effective irrespective of the application methods with higher cob length, 100-kernel weight, and grain yield than the control. Application of Si at 1 mM as seed priming and 300 kg ha–1 as soil incorporation was more effective than other doses and could be recommended as optimum dose for Nakhon Sawan 3 hybrid maize variety under water deficit stress. Drought is one of the major abiotic stresses reducing productivity of field crops including maize. Polyhouse experiment was conducted to evaluate the effects of seed priming of maize with Si on growth, yield, physiological traits, and nutrient uptake under different soil moisture regimes. Treatments consisted of three Si doses (0, 1, and 2 mM) and three soil moisture regimes (100%, 75%, and 50% FC). Si at 1 mM significantly increased growth and grain yield (by as much as 38%) of stressed plants compared with the control plants, and these values did not significantly change when Si dose was increased to 2 mM. At 75 days after sowing, 1 mM Si at 50% FC increased the actual photochemical efficiency of photosystem II by 33% and the electron transport rate by 31% compared with 0 mM Si. Proline content was increased, but total soluble sugar content was decreased with increasing severity of drought stress. However, Si significantly reduced the amount of proline accumulation and increased total soluble sugar content at 50% FC. At 65 days after sowing, proline content was the highest at 0 mM Si + 50% FC, which was reduced by 30% at 1 mM Si + 50% FC. There was no clear increase/decrease in the contents of N, P, K, Ca, and Mg in shoot and grain of Si-treated plants under water-deficit stress, except that N content in shoot was significantly increased with the addition of 1 mM Si. Shoot N, P, K, and Mg contents were higher at 50% FC. An increase in shoot Si content was evident with increasing Si priming dose at 75% FC. These results indicate that priming seed with 1 mM Si was optimum in improving most of the studied parameters under water stress, and could offer perspectives for using it as the recommended dose for maize. Grain yield could be maintained with soil moisture depletion up to 75% FC when seeds were primed with the optimum dose of Si. Silicon-induced yield maintenance in maize under water-deficit stress could be attributed to a better growth performance driven by enhanced values of various physiological traits and Si uptake ability. Priming crop seeds with Si to withstand various abiotic stresses is a novel approach. As soil pH affects dissolution of Si pools and Si uptake by plant, evaluation of this approach in relation to soil pH is needed to understand the effectiveness of this method in different types of soil. Pot experiment was conducted to evaluate the interactive effect of seed priming with Si and soil pH on growth, yield, and nutrient uptake of maize. Completely randomized design with treatments comprising three Si doses (0, 1, and 2 mM) and four levels of soil pH (5.3, 6.3, 7.4, and 8.1) was employed. Overall, Si seed priming with 1 mM gave better performance of maize than did the control (11% higher cob length, 47% more kernel number cob–1 , and 11% higher grain yield and shoot Si). Soil pH from slightly acidic (6.3) to neutral (7.4) was more favorable for growth, yield, and nutrient uptake. Across Si doses, maize produced 21% more kernel number cob–1 and 8% higher grain yield at pH 7.4 than at pH 8.1, whereas plants grown at pH 8.1 had 60% lower shoot P, 12% lower soil K, and 21% lower shoot Si than that grown at pH 7.4. The interactive effect of Si and soil pH was mostly nonsignificant indicating the feasibility of Si application across diverse soil pH ranges. Maize performed poorly at extremely low and high soil pH; the recommendation of Si addition should also take this soil parameter into account. |
| Year | 2019 |
| 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) | Anal, Anil Kumar;Shrestha, Sangam |
| Scholarship Donor(s) | Ministry of Agriculture and Cooperatives (MOAC), Thailand;AIT Fellowship |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2019 |