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1.
We evaluated the effect of soil conservation by weeds on the degradation and generation of humic acids, fulvic acids, and water‐soluble non‐humic substances (WS‐NHS) in a red‐acid soil (Vertic Dystrudept) (Indonesia) from the changes in humus composition and stable carbon isotopic ratio (δ13C). Three plots, a weeded plot (T‐1; the common practice), a plot covered with Paspalum conjugatum Berg., a C4 plant (T‐2), and a plot in which native weeds were allowed to grow (T‐3), were prepared. An incubation experiment determined the δ13C values of the humus fractions generated from Paspalum in soil. Based on the increase in δ13C value, the proportion of total C that originated from Paspalum C after 4 years under coffee was 16 ± 4% in the T‐2 topsoil (0–10 cm). Humic and fulvic acids in the T‐1 topsoil decreased to 46 and 84%, respectively, whilst both increased or remained constant in the T‐2 and T‐3 soils. The WS‐NHS content varied little and was independent of land management. The preferential loss of the humic acids with a smaller degree of humification as assessed by their darkness in colour was shown in T‐1. The decrease in the degree of humification suggested the accumulation of the weed‐derived humic acids in T‐2 and T‐3. In the T‐2 topsoil, 36 ± 2%, 13 ± 3% and 15 ± 2% of C in the humic acids, fulvic acids and WS‐NHS, respectively, were estimated to be Paspalum‐derived after 4 years. The estimated initial C loss during the same period was 17 ± 3%, 14 ± 2% and 7 ± 2%, respectively, for those fractions, which suggests the fastest turnover rate for the humic acids and significant retardation of their degradation in soil colonized by weeds.  相似文献   
2.

In South Asia, an increasing population and frequent droughts have been significant factors deeply affecting water deficits in the region. In this study, recent drought conditions were evaluated by calculating the standardized precipitation index (SPI) for the period of 1991–2006, based on past data during the period from 1961 to 1990. In addition, the Thornthwaite equation was used to compute monthly potential evapotranspiration for the entire area of Indonesia. The APHRODITE data set was utilized for precipitation and temperature. Monthly rainfall data from April to September for 30 years (1961–1990) were used to obtain the gamma function for the computation of SPI values. Calculated probability of SPI for which values were < − 2 during the period from 1991 to 2006 was used to evaluate recent Indonesian drought conditions. Regarding potential soil water deficits, under the very simple assumption that the root zone is 30 cm, soil porosity is 0.4, and field capacity is 80% of soil porosity, the critical threshold of soil water deficit was set as − 96 mm. Frequency of potential water deficits < − 96 mm was counted during 1991–2006. The results of the SPI in Indonesia indicate that most parts of Indonesia have encountered severe and extreme drought for the period 1991–2006. Based on SPI interpretation, Borneo Island and West Papua are the islands that encountered the most extreme drought during the dry seasons. Borneo Island seems to have encountered extreme drought at the beginning and the middle of the dry seasons (April, May, and July). On the other hand, based on the Thornthwaite interpretation, Java and Bali Islands, and especially in Central Java and East Java, seem to have encountered the greatest soil water deficit at the middle and the end of the dry seasons (May, June, July, and September).

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3.
This study was conducted to investigate the effects of salinity stress and flower number on growth, yield, water use efficiency (WUE), and fruit quality of cherry tomatoes cultivated under soilless conditions. The experiment was conducted in a plastic house (5-m wide × 11-m long) located in Gifu University. The seedlings were transplanted in a randomized complete block design with six plants per treatment (NT1 and ST1 were with four plants), giving a total of 44 plants in 22 pots (two plants per pot). Two different salinity levels [no-salinity and salinity with electrical conductivity: 0.8 and 3.0 dS m?1, respectively] and four flower number treatments (8, 13, 18, and free per truss) were investigated in the experiment. The results showed that salinity stress negatively affected tomato growth, yield, and marketable yield, but improved tomato fruit quality. The number of flowers had no effect on tomato growth variables and WUE, but the yield significantly increased with increasing flower number. However, the fruit quality was decreased with increased flower number. A reasonable control for fruit load can increase marketable yield in commercial cultivation. Under salinity stress conditions, properly increasing the number of flowers can avoid yield reduction.  相似文献   
4.
We investigated the use of irrigation water for a successive planting of watermelon followed by Japanese radish in a sand dune area in the Hokuriku Region. The main results were as follows: (1) Upland field tested in the study used a large volume of irrigation water in spite of its location in the Hokuriku Region where rainfall was plentiful. Notwithstanding this, frequent irrigation was considered necessary. (2) Watermelon was cultivated as a Spring–Summer crop with a mean cultivation period of 102 days, during which it was irrigated for 59 days at 1.7-day average intervals with an irrigation volume of 7.1 mm/watering and a total irrigation volume of 428 mm over its entire growing season. The amount of rainfall during the period was 604 mm during 42 days of rainfall. Soil moisture levels in the upland field were kept at relatively high values ranging between pF1.3 and pF1.5 at 15-cm depth with frequent irrigation during no-rainfall period. (3) Japanese radish was cultivated as a Summer–Autumn crop with a mean cultivation period of 71 days during which it was irrigated for 39 days at 1.9-day average intervals with an irrigation volume of 9.4 mm/watering and a total irrigation volume of 358 mm over its entire growing season. The amount of rainfall during the period was 376 mm during 29 days of rainfall. Frequent irrigations were used to maintain the soil moisture levels in the upland field within the range of pF1.4–pF1.6 at 15 cm depth. (4) During the irrigation period, the amount of water used for irrigation was 5.9 mm/day in watermelon and 6.1 mm/day in Japanese radish which are greater than evapotranspiration (ET). In addition, during pre-irrigation, the preparation of the seeding bed can be carried out at the right time which contributes to producing high-quality Japanese radish in adequate quantity. In addition, pre-irrigation for preparation of bed for watermelon transplanting is very important for better time management and high-quality production. For this purpose, the irrigation facilities need to be functioning very well.  相似文献   
5.
This research has experimentally investigated the interactive influences of salinity stress and leaf thinning on the growth, yield, water use efficiency, and fruit quality of cherry tomatoes cultivated under soilless conditions. The experiment was conducted in a plastic house (width of 5 m and length of 11 m) located in Gifu University. The seedlings were transplanted in a randomized complete block design with six plants per treatment, and a total of 36 plants in 18 pots (two plants per pot). The experiment received salinity treatment (no-salinity and salinity with electrical conductivity (EC) of 0.8 dS m?1 and 3.0 dS m?1, respectively) and leaf thinning treatment (no leaf thinning, basal leaf thinning and intersegment leaf thinning except the closest two). The experimental results showed that salinity stress negatively affected the growth, yield, marketable yield and water use efficiency of cherry tomatoes, but positively affected the fruit quality. Basal leaf removal significantly decreased the biomass, chlorophyll, and yield but significantly improved the fruit quality; that basal leaf removal coupled with salinity stress showed no influence on plant growth, but reduced the yield and greatly improved the fruit quality. Besides, tender leaves around truss removal significantly decreased the biomass, chlorophyll, yield, and water consumption, but improved the fruit quality; that tender leaves around truss removal coupled with salinity stress greatly decreased the biomass, chlorophyll, yield, and water consumption, but significantly improved the fruit quality.  相似文献   
6.
A field experiment was conducted to investigate the effects on soil properties of solarization combined with rice bran additive. The treatments included control (bare soil), black polyethylene film mulch (BM), clear polyethylene film mulch (CM), rice bran mixture (RBMx), rice bran mulch (RBM), rice bran mixture and black polyethylene film mulch (RBMx + BM), rice bran and black polyethylene film mulch (RBM + BM), rice bran mixture and clear polyethylene film mulch (RBMx + CM), and rice bran and clear polyethylene film mulch (RBM + CM). Initially, 15 kg m−2 of rice bran was applied to each treatment as the organic amendment. A cover of black or clear polyethylene film was then used to begin the soil solarization process. Approximately 49 days later, the polyethylene film was removed and five broccoli seedlings per replication were planted 6 weeks later. The combination of rice bran mixture with the clear/transparent polyethylene film mulch (RBMx + CM) raised both the mean and maximum soil temperatures over 0–30 cm of soil depth. Maximum soil temperature under the RBMx + CM treatment was the highest of all treatments (77°C) and were about 32°C greater than under the control, while it was only 52°C under RBM + BM treatment. Combining rice bran with clear/transparent polyethylene film mulch during the soil solarization process is recommended for raising soil temperatures. Further investigation over a longer period of soil solarization process with rice bran–organic amendment and polyethylene film mulch combinations is required to more accurately determine their effects on soil properties and crop production.  相似文献   
7.
In this study, partial substitution of wheat flour with chickpea flour at the levels of 10, 20 and 30% was carried out to study their rheological and baking performance. Chickpea flour addition increased the water absorption and dough development time (p < 0.05), while, the extensibility of dough and the resistance to deformation were reduced. Regarding dough stability, it appears that 10% chickpea exhibited higher stability and resistance to mechanical mixing values than the control, while it decreased as the substitute level increases from 20% to 30%. The dough surface of the wheat dough and the blend with 10% was classified as “normal”, however the blend with 20% and 30% produced “sticky” dough surface. The presence of chickpea flour in dough affected bread quality in terms of volume, internal structure and texture. The color of crust and crumb got progressively darker as the level of chickpea flour substitution increased. While the substitution of wheat flour with 10% chickpea flour gave loaves as similar as control.  相似文献   
8.
This study investigated the effects of salinity stress at different growth stages on the growth, yield, fruit quality, and water-use efficiency (WUE) of tomato (Solanum lycopersicum) plants cultivated under soilless conditions. Six different growth stages were exposed to the same salinity stress treatments using a completely randomized design, with three pots (six plants) per treatment. It was found that short-term (<21 days) salinity stress during any of the growth stages did not affect tomato growth or WUE, and during the vegetative stage did not affect yield. Salinity stress during the flowering and fruiting stages caused a reduction in tomato yield, which was due to a reduction in the number of fruit produced rather than the fruit size. However, salt exposure at the fruiting stage also improved fruit quality. The effect of salinity stress on the yield and fruit quality of the frontal and later truss depended on the developmental stage of the truss at the time when the stress occurred.  相似文献   
9.
Species of the genus Vibrio have been recognized as one of the most significant pathogens in aquaculture farming, causing mass mortality of farmed stocks. Photodynamic Antimicrobial Chemotherapy (PACT) with singlet oxygen (1O2) has been identified as a powerful and sustainable water treatment method for pathogen eradication. In this study, the efficiencies of photolytic and photodynamic disinfection protocols were studied with two Vibrio species, Vibrio parahaemolyticus and Vibrio owensii. The selected microorganisms were successfully cultivated in marine broth and irradiations were performed with ~108 bacteria mL?1. Treated samples were monitored for bacterial regrowth for up to 7 days. Photolysis experiments were initially conducted with UV‐A, UV‐B for up to 2 h and visible (VIS) light for up to 24 h. Of these, only irradiation with UV‐B light for at least 45 min was efficient in controlling Vibrio. Irradiations with VIS light were subsequently repeated under PACT conditions in dose?response experiments with two water‐soluble porphyrins, [T4(MePy)P] and [TPPS4]. Disinfections of samples were successful for both porphyrin types at minimum concentrations of 10 μM and 24 h of irradiation.  相似文献   
10.
The objective of this research was to investigate the effect of water stress in regulated deficit irrigation (RDI) on the yield of soybean growing on Ultisol soil. This research was conducted under plastic house on the experimental farm of Lampung Polytechnique from August to November 2004. The water stress treatments in regulated deficit irrigation were ET1 (1.0 × ETc), ET2 (0.8 × ETc), ET3 (0.6 × ETc), ET4 (0.4 × ETc) and ET5 (0.2 × ETc), arranged in a randomized block design with four replications. ETc means crop evapotranspiration under standard condition, which was well watered. For example, the ET2 (0.8 × ETc) treatment means that the amount of supplied water per a day is the same as the crop adjustment evapotranspiration (ETcadj) with the value 0.8 of water stress coefficient (K s). The RDI treatments were carried out just at vegetative phase and its treatments were stopped at the beginning of flowering phase, and afterwards the treatments were watered at 1.0 × ETc. The results showed that since week II, the soybean experienced stress throughout the growth period except ET2 treatment. ET2 treatment started to be stressed at week V and continued to be stressed until the harvest time. At the ET3 treatment, the critical water content (θc) of soybean was reached at week II, and the θc was 0.24 m3/m3 on the average. The RDI at vegetative period significantly affected the yield. The highest yield was ET1 (35.2 g/plant), followed by ET2 (31.0 g/plant), ET3 (18.1 g/plant), ET4 (7.6 g/plant), and ET5 (3.3 g/plant). The optimal water management of soybean with the highest yield efficiency was regulated deficit irrigation with water stress coefficient (K s) of 0.80 for vegetative phase.  相似文献   
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