چكيده لاتين
Plants require adequate access to vital nutrients for optimal growth, and limitations resulting from nitrogen (N) and phosphorus (P) deficiency can significantly reduce their performance and health. The use of beneficial rhizosphere bacteria, particularly Paenibacillus strains with the ability to fix atmospheric nitrogen and solubilize insoluble phosphate, as biofertilizers can increase plant access to these elements and reduce the environmental impact of using chemical fertilizers. In this research, the effect of inoculation with Paenibacillus bacteria combined with Hoaglandʹs nutrient solution was investigated on the growth and physiological indices of ʹCanyonʹ tomato (Solanum lycopersicum) plants. First, the strainʹs ability for nitrogen fixation and insoluble phosphate solubilization was confirmed using specific Winogradsky and Sperber media, respectively, and then a suspension was prepared and used for plant treatment. Sterilized seeds and seedlings were planted in a hydroponic substrate consisting of a peat moss and perlite mixture. The treatments consisted of three different levels of Hoagland nutrient solution concentrations at ratios of (1/"4" ), (1/"8" ) and (1/"12" ), each of which was investigated in two states: with bacterial inoculation and without bacterial inoculation. The indices examined included shoot length, leaf area, relative water content (RWC), electrolyte leakage (EL), and the content of photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids). Statistical analysis was performed using two-way analysis of variance (ANOVA) and Duncanʹs multiple range test. The results indicated that inoculation with the Paenibacillus bacterium at all nutrient solution levels (1/"4" , 1/"8" and 1/"12" ) improved the plantʹs growth and physiological indices compared to the non-inoculated treatments. Specifically, shoot length increased by 11.94%, 25.61%, and 28.3% in the inoculated treatments, respectively. Leaf area was also greater by 22.3%, 56.53%, and 56.65%, respectively. Relative water content of the leaf increased by 3.67%, 3.19%, and 4.85% in the same order. In contrast, electrolyte leakage decreased by 40.2% and 29.8% in the (1/"4" ) and (1/"8" ) treatments, respectively. Furthermore, total chlorophyll increased by 15.81%, 25.1%, and 18.51% at the (1/"4" ), (1/"8" ) and (1/"12" ) levels, respectively, and carotenoids increased by 9.67%, 10.94%, and 14.41%, respectively, compared to their corresponding non-inoculated treatments. The highest growth and best physiological indices were related to the (1/"4" ) Hoagland plus bacteria treatment, and the lowest was related to the (1/"12" ) Hoagland without bacteria treatment. Overall, Paenibacillus bacteria, as an effective biological agent, can enhance the performance and health of tomato plants under restricted nutritional conditions by improving nutrient uptake and promoting growth and physiological indices. This highlights the importance of using beneficial soil bacteria in the development of biofertilizers and increasing agricultural productivity.
