In order to evaluate the salt tolerance level of Jatropha curcas L., effects of salt stress on early growth and photosynthesis were investigated at Cairo University, Egypt, for salty irrigation use. Plants were cultivated in about 15 L plastic pots filled with field soil (Vertisol) and chemical fertilizer (5g, N:P2O5:K2O=8%:28%:24%). Salt treatments were started from 160 days after sowing as Experiment 1 in winter and 120 days after sowing as Experiment 2 in summer. 400mL of 0, 2000 and 4000 ppm NaCl solutions were irrigated every morning for 2 weeks. The highest soil EC was about 1mS cm-1, which was observed in 4000 ppm NaCl treatment. The photosynthetic rate of J. curcas was decreased under salt treatment conditions. Although photosynthetic rate was influenced by salt treatment, growth and dry weight were not. Fresh and dry weights of J. curcas were higher in Experiment 2 than those in Experiment 1, hence in winter in Cairo, J. curcas may not be able to grow sufficiently. Therefore, to confirm the maximum salty level for its cultivation, plants were cultivated under 0 ppm, 2000 ppm, 4000 ppm, 6000 ppm, and 8000 ppm NaCl treatments at University of Tsukuba, Japan, as Experiment 3. A high salt treatment solution affected to the dry weight of J. curcas at harvest severely, while under 7.5 mS cm-1 (≒4000ppm) solution showed about 82% of dry weight of the above ground part in control. In addition, lower leaves stored high content of Na, compared with upper and young leaves. It was estimated that J. curcas stored salt in lower leaves, not translocating it to upper and young ones to inhibit photosynthesis ability.
Jatropha (Jatropha curcas L.) is well-adapted to arid areas and thus has been recognized as a new energy crop for bio-diesel production in Africa. Low temperatures due to radiative cooling effects are known to cause frost damage to jatropha and this is an important limiting factor of its cultivation in Gaborone, Botswana. To mitigate heat loss at night and rapid increments of light intensity and air temperature after dawn, shading screens were applied to field-grown jatropha. Then, the protection effects and the photosynthesis after being damaged by frost were examined. Cold waves severely damaged branches and leaves of jatropha trees; however, this damage was greatly alleviated by the shading treatments. Without shading, nearly half of the branches showed blackened apexes and most of the leaves had fallen off, while only a few branches were damaged and a number of leaves were maintained in the shading plots. The number of inflorescences was also higher in these plots though it was investigated earlier than the flowering period, therefore further observation is surely necessary. Photosynthesis measurements suggested that shading significantly reduced CO2 assimilation and transpiration rates of jatropha leaves due to the limited sunlight, yet the shaded leaves properly functioned in response to changing light intensity. From these results, it was concluded that shading was an effective technique to protect jatropha branches and leaves from frost damage, which may have further improved inflorescence formation as well. Shading screens need to be removed after winter to increase light availability and enhance photosynthetic ability.
In this study, we cultivated three local Okinawa varieties (O-higu, Taka-anda, Hiku-anda) of soybean (Glycine max), investigated their seed properties, and compared these with those of other soybean varieties that are cultivated or imported for commercial use in Japan. Based on the results, we describe the following component characteristics of the local soybean varieties in Okinawa: 1) The seed size of all Okinawa local soybean varieties was smaller than that of other varieties; 2) The Okinawa local soybean varieties (and O-higu in particular) had a relatively high protein content; 3) O-higu contained a relatively high level of oligosaccharides compared to the other varieties; 4) Okinawa local varieties also had a low ω6/ω3 value compared to the other varieties, and the ω6/ω3 value of the Taka-anda was significantly lower than that of all Japanese and imported varieties; 5) Within local Okinawa varieties, the isoflavone content of Taka-anda was the highest. In contrast, the content of isoflavone in O-higu was lower than that of other local Okinawa varieties; 6) Local Okinawa varieties contained higher levels of phytic-phosphorus than the imported varieties.
Utilizing less water while maintaining yields is vital to sustain the irrigated maize (Zea mays L.) production in Thailand. In a field experiment, maize plots were fertilized with three levels of manure (0, 6.25, and 12.5 t ha-1) and furrow irrigation was conducted at 1-, 2-, and 3-week intervals from 43 to 92 days after sowing. Lengthening the irrigation interval to 2 and 3 weeks reduced irrigation water by 29% and 36%, respectively. Lengthening the irrigation interval inhibited plant height, while the application of manure promoted plant height at the vegetative stage. Photosynthetic rates at early ripening stage, dry weight at maturity, and grain yield were markedly inferior in the 3-week interval irrigation, but there was no significant difference between 1- and 2-week interval irrigation groups. Application of manure slightly increased dry weight, grain yield, and water use efficiency, although the difference was not significant, probably due to insufficient manure levels or clayey soil. Lengthening irrigation interval increased carbon isotope discrimination, indicating that the relative activity of C3 to C4 photosynthetic pathway declines. In a pot experiment, manure application alleviated growth inhibition, yield reduction, and increase in carbon isotope discrimination caused by soil water stress. These results suggest that the lengthening irrigation interval from the late vegetative to the early ripening stage to 2 weeks saves water without affecting growth and yield, and manure application may enhance dry matter production and increases grain yield.
This study aimed to assess the effectiveness of compost application on the production of rice (Oryza sativa L.). Two types of compost were examined: sewage sludge compost (SSC) and food waste compost (FWC), both of which were prepared from cyclical food resources, wood chips, and grass clippings. Pot experiments were conducted over two years, during which the effects of both these composts on the growth and yield characteristics of rice were analysed. Additionally, the total nitrogen (N) level, which was the total amount of compost applied to the soil, in both these composts varied between 5.5-22.0 g N per 24 L pot and was compared with 6.1 g N per 24 L pot of chemical fertilizer (CF) as conventional cultivation. The tiller number at the early stage and number of productive panicles per hill were the smallest among plants treated with FWC, followed by SSC, and the largest among those treated with CF. On the other hand, average number of spikelets per panicle and percentage of ripened grains were the highest among plants treated with SSC and FWC than that treated with CF. As the quantity of SSC increased, the yield of SSC treatments was increased. On the other hand, FWC had a peak of yield by increasing FWC application. Considering the changes of tiller number, maturity stage, yielding ability and economically, SSC containing 11.0 g N pot -1 could be used as an alternative to CF (6.1g N pot -1) utilized in the range of application amount of this experiment.
Food waste and sewage sludge are good sources for making organic compost which contain many kinds of plant nutrients and release slowly. To recover the early growth inhibition of rice plants which affected by the application of sewage sludge compost (SSC) and food waste compost (FWC) and to improve rice yield, the pot experiments were conducted with seasonal repetitions for three years. Experimental design was made by combination of the following factors: types of compost (FWC and SSC), different amount (5.5, 11, 16.5 and 22 g Nitrogen per 24 L pot), compost application methods (uniform application and side dressing), and transplanting dates as seasonal repetition (three repetitions in 2015, two in 2016 and one in 2017) and compared with chemical fertilizer treatment and no fertilizer treatment. The depression effects of FWC application on rice growth was more than SSC in all repetitions. The tiller number were most affected than the other growth parameters and root development than other biomass productions. These phenomena were found to be improved and recovered by late transplanting and side dressing of compost under the condition of the same type and amount of compost. Uniform application of compost which is common in rice production, caused inhibition effects at the early growth stage of rice plants. In order to use compost as basal dressing, side dressing was considered to be useful to decrease the inhibition effects of both composts at the early growth stage, especially for FWC. The side dressing of compost also produced more yield than that of uniform application.