The present study was conducted to investigate the effects of Trichoderma harzianum and Bacillus thuringiensis alone or with gradual levels of NPK on photosynthesis, growth, fruit quality, aroma improvement and reduced radionuclides of key lime fruits. The lemon seedlings were treated with (T0) without fertilizers as control, (T1) 100g of NPK at 100%, (T2) 5 g of Trichoderma. harzianum at 50% + 50 g of NPK at 50%, (T3) 5 g of Bacillus thuringiensis at 50% + 50 g of NPK at 50 %, (T4) 7.5 g of Trichoderma harzianum at 75% + 25 g of NPK at 25 %, (T5) 7.5 g of Bacillus thuringiensis at 75% + 25 g of NPK at 25 %, (T6) 10 g of Trichoderma harzianum at 100 % and (T7)10 g of Bacillus thuringiensis at 100 %. The results showed that T2 increased net photosynthetic rate, stomatal conductance, transpiration rate, internal CO2 concentration, fresh and dry root biomass by 209%, 74%, 56%, 376%, 69.4% and 71.6%, while, T5 increased root volume, root length, and root tip number by 27.1%, 167%, and 67%, respectively over the control trees. The microbial treatments developed cortex, vascular cylinder and tracheal elements of the root. Fruit number, length, diameter, weight, pulp thickness, pulp/peel ratio, juice, total soluble solids (TSS), pigment contents and antioxidant activity increased significantly in the T2 treatment. Vitamin C, total phenols, total flavonoids, and total sugar content increased by 1.59-, 1.66-, 1.44- and 2.07- fold in T5 treated fruits compared to the control. The two microbes increased volatile compounds and decreased radionucleotides in the fruit, moreover, 27 identified and 2 (two) unmatched volatile compounds were identified by GCMS analysis. It is concluded that T. harzianum and B. thuringiensis with 25-50 g NPK treatments improved photosynthesis, root structure, fruit growth, fruit quality, aroma and lessened radionuclides in key lime fruits.
Growth improvement of the medicinal plant, Ficus deltoidea (Mas Cotek) under drought conditions is a vital issue in Malaysia since it is a slow-growing plant and disposed to leaf damage under the stresses of drought. Therefore, investigation was done to examine the outcomes of hydrogen peroxide (H2O2) application on Rubisco gene expression and metabolites accumulation of stressed F. deltoidea plants, and thereby to record the changes in leaf histology, photosynthesis, biochemical properties, and the growth of the plant. H2O2 at the rates of 0, 5, 10, 15, and 20 mM were foliar sprayed biweekly on the drought stressed plants using a hand sprayer. The application of 20 mM H2O2 amplified leaf number, tallness, stomatal conductance, and photosynthetic yield by 143, 24, 88, and 18%, respectively, over the control plant. A reduced transpiration rate and improved chlorophyll fluorescence were also noted in H2O2-treated plants. The treatment produced a greater amount of chlorophyll a, total phenols, total flavonoids, sugar content, and antioxidant activities by 1.61-, 1.30-, 1.98-, 1.92-, and 1.53-fold, respectively. Application of 15 mM H2O2 enhanced net photosynthetic rate and internal CO2 concentrations by 1.05- and 1.25-fold, respectively. Additionally, H2O2 treatments promoted stomatal closure, increased stomata size, the number of stomata, improved vein structure, and reduced the damage of the leaf margin and mesophyll cells of drought stressed plants. The application of H2O2 also accumulated significantly higher contents of sodium (Na+), calcium (Ca2+), potassium (K+), magnesium (Mg+), and iron (Fe2+) in stressed plants. Although the amount of Arsenic (As+) and Antimony (Sb3+) increased to some extent, the increases were not at a toxic level. The use of H2O2 enhanced the Rubisco gene expression to a greater level and the ratio of Rubisco expression increased up to 16-fold. Finally, thirteen (13) identified and five (5) unmatched volatile compounds with a quality score above 70% were identified by gas chromatography-mass spectrometry (GCMS). The GCMS analysis showed that the foliar application of H2O2 accumulates a higher percentage of volatile components in plants which helps to mitigate the negative effects of drought stress. It is concluded that under drought stressed conditions the F. deltoidea plants should be treated with 10-15 mM of H2O2 twice a week to improve leaf histology, photosynthesis, the level of Rubisco gene expression and volatile compounds accumulation, and plant growth and development.