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Abstract

Humidity levels control directly the rate of transpirational water loss and stomatal aperture of plants. Thus, humidity regulates photosynthetic rates, tissue temperatures, plant water potentials, and concentrations of Ca in certain tissues. Humidity also controls water taken in by tissues through condensation and direct vapor uptake.
... Similarly, relative humidity has a direct impact on plant growth and development. It signi cantly in uences plant photosynthesis, tissue temperature, plant water potential, and calcium concentration in various tissues (Tibbitts 1979 these parameters were within the optimal range for djulis growth (Fig. 1-3) and contributed to the successful growth and yield of both the red and yellow lines, especially with the application of PNSB as a biofertilizer. ...
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Background: Djulis is a nutrient-rich plant with potential health benefits, but its intensive fertilization hinders its yield, raising environmental concerns. Biofertilizers like purple non-sulfur bacteria (PNSB) offer an eco-friendly alternative to enhance growth and yield, yet limited research has investigated their efficacy on different djulis lines. Therefore, the current study aimed to investigate PNSB's effectiveness on two djulis lines in two fields, one control and the other inoculated with PNSB. Methods: Data on the growth and yield of djulis lines were collected and the results were statistically analyzed using independent sample t-tests and Duncan's multiple-range test. Results: The results showed that PNSB inoculation in the red line led to a significant increase in plant height (24%), leaf chlorophyll content (15%), spike length (35%), spike fresh weight (94%), shoot dry weight (207%), grain yield (86%), root length (119%), root volume (100%), and root dry weight (23%). As in the yellow line, PNSB inoculation significantly increased plant height (14%), spike length (26%), spike fresh weight (43%), shoot dry weight (53%), root length (36%), root volume (72%), and root dry weight (24%). Inoculation of PNSB had opposite effects on the maturity period of red and yellow djulis lines. It significantly improved the yield of the low-performing red line but had only minor effects on the high-performing yellow line, indicating the importance of selecting suitable lines. Conclusion: This study highlights PNSB's potential as a sustainable and cost-effective biofertilizer for djulis production and encourages further research to explore its applications in other crops and environments.
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Background: Djulis (Chenopodium formosanum Koidz.) is a nutrient-rich plant with potential health benefits, but its intensive fertilization hinders its yield, raising environmental concerns. Biofertilizers like purple non-sulfur bacteria (PNSB) offer an eco-friendly alternative to enhance growth and yield, yet limited research has investigated their efficacy on different crop lines or varieties. Therefore, the current study aimed to investigate PNSB's effectiveness on two djulis lines in two fields, one control and the other inoculated with PNSB. Methods: Data on the growth and yield of djulis lines were collected, and the results were statistically analyzed using independent sample t-tests and Duncan's multiple-range test. Results: The results showed that PNSB inoculation in the red line led to a significant increase in plant height (24%), leaf chlorophyll content (15%), spike length (35%), spike fresh weight (94%), shoot dry weight (207%), grain yield (86%), root length (119%), root volume (100%), and root dry weight (23%). As in the yellow line, PNSB inoculation significantly increased plant height (14%), spike length (26%), spike fresh weight (43%), shoot dry weight (53%), root length (36%), root volume (72%), and root dry weight (24%). Inoculation of PNSB had opposite effects on the maturity period of red and yellow djulis lines. It significantly improved the yield of the low-performing red line but had only minor effects on the high-performing yellow line, indicating the importance of selecting suitable lines. Conclusion: This study highlights PNSB's potential as a sustainable and cost-effective biofertilizer for djulis production, bolstering both food security and agricultural productivity.
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Many investigations have been made on transpiration and photosynthesis of plants. However, the relationship between transpiration and photosynthesis has not been completely estabilished. The study reported here was planned to elucidate the effect of transpiration on the apparent photosynthesis and the relation of temperature and photosynthesis in several crops: sweet potato, rice, soybean and peanut. 1) Experiments were conducted outdoors under full sunlight using an apparatus which has a humidity-controlling system (Fig. 1). In early growth stage, photosynthesis was not affected by restraint of the transpiration caused by increasing humidity in the chamber, but in late growth stage a marked increase of photosynthetic rates occurred by restraining the transpiration (Figs. 2-5). These results suggest that water supply from root to the photosynthetic organ turns insufficient in the late growth stage. 2) Fig. 6 and Fig. 7 indicate the relation of leaf temperature and photosynthesis in sweet potato and soybean plant at various growth stages. In early growth stage, apparent photosynthesis was insensible of high temperature from 30 to 40°C. In late growth stage, however, apparent photosynthetic rates showed a rapid decrease at high-temperature range. These phenomena were also recognized in other crops, e.g., rice and peanut. From results of the investigation for the stomatal opening and fluctuation of water level in sweet potato leaves under various temperature condition, it may be concluded that depression of photosynthetic rate at high-temperature range was due to a deficit of water content and high stomatal resistance in leaf. 3) In the series of experiments as shown in Figs. 2-5, water vapour transfer coefficient (D) was calculated for several crops from the equation presented in the note of Fig. 9. There was a close relationship between the transpiration and the ‘D’ value. The ‘D’ values, selected under approximately constant conditions with leaf temperature of 35°C and air volume passing through a chamber of 8-11 m³/hr, showed high correlations to photosynthetic rates in three crops except soybean plant (Fig. 10). The ‘D’ value is a reciprocal of diffusion resistance(r) which can be divided into two components: (i) resistance in external air during diffusion away from leaf(ra), and (ii) resistance through the stomata(rs). It is considered that the ‘D’ mainly depends on 1/rs in the case of Fig. 10. Accordingly, when photosynthetic rate is high at high leaf temperature, stomata are widely open. 4) Two factors, total sugar content in root and the ratio of root dry weight (R) to leaf area (F), must be concerned with the water supply from root to photosynthetic organ. Therefore, both factors, whose changes with time are shown in Fig. 14, would be correlated to the ‘D’ values of each growth stage.