Effects of Water Availability, Temperature, and Soil pH on Plant Growth and Physiological Performance

Abstract

Abiotic stresses (water stress, temperature extremes, suboptimal soil pH) are the major limiting factors to plant productivity and agricultural stability throughout the world. The independent and interactive effects of these stressors need to be determined in order to develop resistant cultivars and effective management practices. This study assessed the main and interaction effects of three water levels (100%, 60%, and 30% field capacity), three temperature regimes (25degC, 32degC, and 38degC), and three levels of pH (5.0, 6.5, and 8.0) on growth, physiological and biochemical responses of Solanum lycopersicum (tomato). A full-factorial approach was adopted under the control of greenhouse conditions. Results showed that each of the stressors when applied individually significantly decreased plant height, biomass accumulation, leaf area, photosynthetic rate and stomatal conductance. The biggest drops were under combined high-stress treatments. For instance, the 30 percent field capacity and 38 degrees Celsius treatment combination was especially detrimental regardless of soil pH. Moreover, the suboptimal pH values (5.0 and 8.0) enhanced the negative effects of drought and heat stress, presumably through limiting nutrient supply and root growth. Biochemical analyses showed significant elevation of proline level and antioxidant enzyme (catalase and superoxide dismutase) activities in stress condition, suggesting an induced defense response, which was, however, not able to prevent significant physiological damage under severe conditions of combined stress. These findings highlight the critical importance of dealing with abiotic stressors in concert, as the negative impacts they have are substantially higher than the additive negative impacts of the different stresses.