Effect of thermal radiation on thermal flow field in inclined tunnel

The thermal radiation is the main factor affecting internal thermal flow field in a tunnel. This paper studies on two open ends of a channel inclined with angles of 10°, 20° and 30° by experiments and numerical simulations. The experimental data agree well with the predicted results by using Large Eddy Simulation (LES) to solve N-S equations driven by the buoyancy flow. And the influence of thermal radiation on thermal flow field of tunnel with inclination angles from 10° to 30° at same heat source is obtained by comparing the experiment results and numerical resolutions of coupled with radiation model and without radiation model. Thermal radiation makes temperature near the upper wall of tunnel drop, and the influence of thermal radiation on bottom end of tunnel declines with the inclination angle increasing. However, the inclination angle has a little effect on temperature near the ceiling of the top end of tunnel. Simultaneously, the higher temperature zone leaning to the top end due to the thermal radiation is obtained, and the temperature at the bottom of the upper part of the tunnel increases. The findings of the study are important references for theory research of thermal flow field in inclined tunnels.     

Effect of Extending the Growing Period on Yield Formation of Sugar Beet

Autumn sown sugar beets (winter beets) are expected to yield markedly higher than spring sown beets. This requires a continuous growth during an extended growing period. So far, bolting‐resistant sugar beet varieties are not available to test winter beets under field conditions in Central Europe. The objective of this study was therefore to analyse yield formation and sugar storage of sugar beet plants during an extended growing period to estimate whether sugar beet has the potential to generate the theoretically expected yield increase. From 2008 to 2012, pot experiments were carried out in the glasshouse with 11 sowing dates spread over the years with sequential harvests. The oldest plants were grown for 859 days (14 242 °Cd). Root fresh matter yield continuously increased till the latest harvest. In contrast, the sugar concentration reached an optimum value between 3400 and 5000 °Cd and then decreased with time. Despite longer growing periods, the number of cambium rings, which are regarded as essential for sugar storage, did not change. This points to an early and genetically fixed determination of the formation of cambium rings. Additionally, the rate of photosynthesis decreased concomitantly with the sugar concentration. In conclusion, there is some evidence that the sugar concentration of the storage root is limited by the sink capacity, which in turn controls the source activity by a feedback regulation of photosynthesis and leaf formation. The dry matter composition of the storage root changed towards lower sugar concentration and concurrent higher concentration of cell wall compounds (marc). The sugar yield still increased beyond a thermal time at which winter beets will probably be harvested in practice. Hence, the theoretical yield increase in autumn sown sugar beets can be realized, provided that the plants show sufficient winter hardiness and bolting resistance.     

苹果渗透脱水的响应面优化分析

以渗透时间、渗透温度、渗透液浓度和反应的固液比为自变量,以失水率、固形物增加率,以及干燥后产品的复水率为应变量,对苹果进行渗透脱水响应面试验研究。应用响应面分析的方法对试验结果进行优化分析,得出最佳工艺为:渗透时间为110min,渗透温度为35℃,渗透液的浓度为40°Brix+质量分数为4.5%的NaCl,反应的固液比为1∶10。     

Freezing Resistance and Development of Faba Beans as Affected by Ambient Temperature, Soil Moisture and Variety

Effects of temperature and soil moisture on the development of some plant and leaf traits and of freezing resistance were examined in 5 (6) European varieties of winter faba beans. After pre-growth at 15 °C for 1 week, temperature was kept either at this level or lowered to 8:2 °C (day might). Soil moisture was maintained at 70-90 % of or above field capacity, or was allowed to approach wilting point. At 15 °C, specific dry matter content (D.M. per unit area) and water/D.M. ratio were the only traits in the lower expanded leaves (1-3) that changed markedly with time. Several plant and leaf traits were affected by soil moisture and displayed varietal differences. However, freezing resistance remained unchanged with time and was hardly affected by soil moisture and varieties (Δ R < 0.2 °C). Interestingly freezing resistance and leaf traits were differently expressed in leaves 1-3 of plants and thus contributed to some low correlations between these items. Likewise at 8:2 °C, only low correlations between leaf traits and freezing resistance were established. They were mainly due to developmental effects and soil moisture, since (i) specific water and D. M. content increased in parallel with freezing resistance (rate - 0.45 °C/day), (ii) leaf traits and freezing resistance were differently expressed in leaves 1 and 2 (i.e. -12.5 and -13.5 °C) and (iii) low as well as high soil moisture raised freezing resistance (-0.7°C) and specific D.M. content, but lowered water/D.M. ratio. With the exception of the old French land race Cote ?Or, varietal differences in freezing resistance at 8:2 °C were small (<0.5 °C). Neither in the first nor in the second leaf varietal rank pattern of freezing resistance was consistent with that of other traits and hence no genotypic correlations could be established. On the basis of these data, the usefulness of leaf traits in breeding as indirect criteria for freezing resistance appeared doubtful.     

Impact of High Night‐Time and High Daytime Temperature Stress on Winter Wheat

High temperature is a major environmental factor that limits wheat (Triticum aestivum L.) productivity. Climate models predict greater increases in night‐time temperature than in daytime temperature. The objective of this research was to compare the effects of high daytime and high night‐time temperatures during anthesis on physiological (chlorophyll fluorescence, chlorophyll concentration, leaf level photosynthesis, and membrane damage), biochemical (reactive oxygen species (ROS) concentration and antioxidant capacity in leaves), growth and yield traits of wheat genotypes. Winter wheat genotypes (Ventnor and Karl 92) were grown at optimum temperatures (25/15 °C, maximum/minimum) until the onset of anthesis. Thereafter, plants were exposed to high night‐time (HN, 25/24 °C), high daytime (HD, 35/15 °C), high daytime and night‐time (HDN, 35/24 °C) or optimum temperatures for 7 days. Compared with optimum temperature, HN, HD and HDN increased ROS concentration and membrane damage and decreased antioxidant capacity, photochemical efficiency, leaf level photosynthesis, seed set, grain number and grain yield per spike. Impact of HN and HD was similar on all traits. Greater impact on seed set, grain number and grain yield per spike was observed at HDN compared with HN and HD. These results suggest that HN and HD during anthesis cause damage of a similar magnitude to winter wheat.     

Rice grain-filling characteristics under elevated air temperature in a temperate region

Future climate change accompanied by global warming is expected to change rice growth environments and causes detrimental effects on yield formation processes, leading to reduction of rice yield and quality in many regions. This study was performed to evaluate the grain-filling responses to elevated air temperature above ambient during the grain-filling period after heading in a temperate region (37.27 °N, 126.99 °E; Suwon, South Korea). Six rice cultivars differing in maturity were grown under ambient air temperature conditions before being transferred at the initial heading stage to the plastic houses which were temperature controlled to the targets of ambient temperature (AT), AT + 1.5 °C, AT + 3.0 °C, and AT + 5.0°C.     

Assessment of different anther culture approaches to produce doubled haploids in cucumber (<Emphasis Type="Italic">Cucumis sativus</Emphasis> L.)

Cucumber is one of the most important vegetable crops worldwide, which makes it a good candidate to produce doubled haploid (DH) lines to accelerate plant breeding. Traditionally, these approaches involved induction of gynogenesis or parthenogenesis with irradiated pollen, which carries some disadvantages compared to androgenesis. Despite this, studies on anther/microspore cultures in cucumber are surprisingly scarce. Furthermore, most of them failed to unambiguously demonstrate the haploid origin of the individuals obtained. In this work we focused on anther cultures using two cucumber genotypes, different previously published protocols for anther culture, different in vitro culture variants to make it more efficient, and most importantly, a combination of flow cytometry and microsatellite molecular markers to evaluate the real androgenic potential and the impact of anther wall tissue proliferation. We developed a method to produce DH plants involving a bud pretreatment at 4 °C, a 35 °C treatment to anthers, culture with BAP and 2,4-D, and induction of callus morphogenesis by an additional 35 °C treatment and sequential culture first in liquid medium in darkness and second in solid medium with light. We also found that factors such as genotype, proliferation of anther wall tissues, orientation of anthers in the culture medium and growth regulator composition of the initial anther culture medium have a remarkable impact. Our rate of chromosome doubling (81%) was high enough to exclude additional chromosome doubling steps. Together, our results present androgenesis as an improvable but yet more convenient alternative to traditional gynogenesis and parthenogenesis-based approaches.     

Genotypic difference in spikelet sterility response to air temperature during the reproductive stage of rice

This experiment was conducted to evaluate the varietal differences of spikelet sterility response to air temperature during the reproductive stage. Six rice varieties differing in maturity group (early-maturing; Unkwangbyeo, Odaebyeo, medium-maturing; Andabyeo, Hwasungbyeo, and mid-late maturing; Donganbyeo, Chuchungbyeo) were grown under ambient temperature (AT) conditions before being transferred to the temperature-controlled plastic houses. For the synchronization of the growth stage, 15 rice seedlings (2011) and 10 rice seedlings (2012) per pot were transplanted in a circle and only main stems were grown by removing tillers at early stage of their emergence. At the initial heading stage, pots for each variety were transferred to the four plastic houses that were controlled to AT, AT + 1.5°C, AT + 3.0°C, and AT + 5.0°C, respectively. Spikelet fertility was significantly decreased due to high temperature-induced spikelet sterility at AT + 3.0 and/or AT + 5.0°C treatment during flowering time in 2011. Spikelet fertility in 2012 was much lower than in 2011 even at the AT treatment because of high temperature-induced spikelet sterility at the micosporogenesis stage. Critical temperature (Tc) that induces 50% spikelet sterility at flowering time was estimated by fitting the temperature response of spikelet fertility to a logistic function. Tc ranged from 34.6°C (Odaebyeo) to 39.7°C (Hwasungbyeo), Odaebyeo being significantly more sensitive to high temperature-induced spikelet sterility than the other varieties. This result has shown that response of spikelet sterility to higher temperature is different according to rice varieties. However, further study should be done to arrive at a concrete conclusion.     

Ethanol vapor prior to processing extends fresh-cut mango storage by decreasing spoilage,but does not always delay ripening

This study was undertaken to optimize ethanol vapor application as a ripening inhibitor on whole mangoes to extend fresh-cut mango shelf life. Freshly harvested mangoes were first subjected to hot water (+HW) at 46 °C for 60 or 90 min to simulate quarantine heat treatments, or remained untreated (−HW). Fruit of each batch (+ or −HW) were then held at 20–25 °C for 4 or 7 d (D4 and D7) after the hot water treatment before being exposed to ethanol vapors [0 h (E0), 10 h (E10), or 20 h (E20)]. Fruit were then peeled and cut into slices, packed in plastic clamshells, and stored at 7 °C for 15 d. Only slices from +HW-D4-E20-treated fruit maintained higher firmness, hue angle, and titratable acidity (TA) in storage. The +HW-D7-E10- or E20-treated fruit had higher hue angle than E0, but firmness, total soluble solids, TA, pH, and respiration rate did not differ. Internal ethanol and acetaldehyde were very high in slices from +HW, D4 and D7, E20 and −HW-D7-E20-treated fruit. A sensory panel could perceive higher firmness and acidity in slices from fruit treated with ethanol. However, E20 induced off-flavor, and these fruit were least preferred.Ethanol exposure on fruit was repeated with purchased mangoes that had been subjected to a commercial quarantine heat treatment. A second heat treatment of 18 h at 38 °C and 98% relative humidity was added to one batch of fruit in this experiment. Ethanol vapors did not result in delayed ripening in those mangoes. However, this treatment inhibited microbial growth. The second heat treatment did not improve fresh-cut mango shelf life, and further, microbial growth increased compared to other treatments. It is concluded that, due to inconsistent results, ethanol vapor applied for 20 h to whole mangoes prior to processing for fresh-cut is not a practical approach to delay ripening; however, at lower doses (10 h), it could be used as a safe microbial control in a fresh-cut production sanitation system.     

High CO2 effects on postharvest biochemical and textural properties of white asparagus (Asparagus officinalis L.) spears

The effects of high CO₂ concentration (10% CO₂, 17% O₂) on the changes of functional cell wall components (pectic substances, hemicellulose, cellulose, lignin), mechanical properties, content of free soluble sugars (sucrose, glucose, fructose), and respiration activity were studied in harvested white asparagus spears stored at 10 and 20 °C, respectively, for up to 7 d. Spears stored at 2, 10 and 20 °C in air were studied as controls, where the 2 °C condition indicated the effects of cold storage. During storage, respiration activity declined only slightly, irrespective of the CO₂ and temperature regime. Spears stored at 20 °C under both CA and normal air became less stiff and more elastic, however, tissue toughness increased significantly. Changes in toughness were associated primarily with the dynamics of lignin and cellulose, revealing a strong correlation (r² = 0.81). High CO₂ concentration inhibited the synthesis of cellulose and, to some extent, lignin accumulation at 20 °C. Additionally, elevated CO₂ inhibited the degradation of soluble carbohydrates. In contrast, slightly lower temperatures of 10 °C in combination with high CO₂ did not have a pronounced effect on changes in structural carbohydrates (lignin, cellulose, hemicellulose and pectins). The effect low temperature (2 °C) under normal atmosphere conditions resulted in the inhibition of cell wall changes in asparagus spears.     

Impact of high temperatures on the marketable tuber yield and related traits of potato

A rapid warming of 2.8–5.3 °C by the end of this century is expected in South Korea. Considering the current temperature during the spring potato growing season (emergence to harvest; ca. 18 °C), which is near the upper limit of the optimum temperature for potato yield, the anticipated warming will adversely affect potato production in South Korea. The present study assessed the impact of high temperature on the marketable tuber yield and related traits of cv. Superior (which makes up 71% of the annual potato production in South Korea) in four temperature-controlled plastic houses and an outdoor field (37.27°N, 126.99°E) during 2015–2016. The target temperatures of the four plastic houses were set to ambient (AT), AT+1.5 °C, AT+3.0 °C, and AT+5.0 °C. The marketable tuber yield was significantly reduced by 11% per 1 °C increase over a temperature range of 19.1–27.7 °C. The negative impact of high temperature was associated not only with the yield loss of total tubers, which was mostly explained by the slower tuber bulking rate, but also the reduced marketable tuber ratio under temperatures above 23 °C, which was mainly attributed to the reduced number of marketable tubers (r = 0.79***). Under moderate temperatures below 23 °C, the source limited the number of marketable tubers without reducing the marketable tuber ratio. In contrast, the number of marketable tubers was limited by the marketable tuber set at the early growth stage rather than the source under the higher temperatures, which resulted in the reduction in the marketable tuber ratio below 56%. These results suggest that the objectives of breeding and agronomic management for adapting to the rapid warming in South Korea should include maintaining the ability to form tubers at the early growth stage under high temperatures, as well as the photosynthetic capacity and sink strength of the tubers.     

坡度对云南红壤径流中磷素浓度的影响研究

水体富营养化的发生与农田土壤中磷的淋失有密切的关系。采用模拟降雨试验研究了土壤坡度对地表径流和亚地表径流中磷素浓度的影响。结果表明：在0°—10°范围内,地表径流中总磷、水溶性磷和颗粒态磷浓度和亚地表径流中水溶性磷浓度都随土壤坡度的增加而增加。亚地表径流中总磷和颗粒态磷在坡度为15°时均有一定程度的下降,其下降机理将做下一步分析研究。     

Influence of DO on Nitrification of Municipal Wastewater with Low C/N Ratio

Through the test on activated sludge in SBR reactor,the influence of DO on nitrification is studied.First,through a 195d continuous test,to maintain the DO concentration of nitrifying system at a low level,if the DO is in range between 0.2 mg/l(start) ~0.6 mg/l(end) there will be high NH+4-N reduction and the nitrification ratio will reach 50~90%;Second,according to the regularity of DO in a cycle,12h as a react time is proper.If the react time of 16h is taken,it will be a traditional nitrification.At last,through bottle reactors,it can be concluded that when the DO concentration of system rise,NH+4-N the reduction ratio will rise too,but the nitrification ratio will drop,the NH+4-N reduces and the nitrification ratio can be calculated from a formula.     

Responses to temperature of fruit dry weight,oil concentration,and oil fatty acid composition in olive (Olea europaea L. var. ‘Arauco’)

Correlative studies in olive using data from different locations or years suggest that temperature can modulate crop oil yield and oil composition. However, there are no published studies of manipulative experiments that demonstrate a direct role for temperature as a regulator of oil yield and oil quality in olive. The objectives of this study were to: i) elucidate the effect of temperature during the fruit oil accumulation phase on fruit dry weight, oil concentration and fatty acid composition; and ii) identify the developmental window within the oil accumulation phase exhibiting the greatest sensitivity to temperature and that with the highest fruit capacity to recover from the temperature treatments. Two branch-level experiments were conducted in a commercial orchard at Los Molinos (La Rioja, Argentina) using var. ‘Arauco’. Both experiments were conducted during the oil accumulation phase by enclosing fruiting branches in transparent plastic chambers with individualized temperature control. The first experiment; known as the four month long experiment, employed four temperature treatments that were applied for a single period of four months: a control at ambient temperature, two heating levels (5 °C and 10 °C warmer than the control), and a cooling level (5 °C cooler than the control). The second experiment consisted of four separate successive one month long treatment periods, in each of which two temperature treatments were applied: control and heating (ca. 7 °C higher than control). In the four month long experiment, fruit dry weight was not affected by average temperatures in the 16–25 °C range, but it was reduced with further increases in temperature. Oil concentration decreased linearly at 1.1% °C⁻¹ across the whole range (16–32 °C) of average seasonal temperatures explored, while oleic acid concentration decreased 0.7% °C⁻¹ over the same range. In the one month long experiment, 30 days of temperatures ca. 7 °C above ambient had a permanent negative effect on oil concentration at final harvest, particularly when the exposure to high temperature took place at the beginning of oil accumulation. By contrast, oleic acid concentration at the end of the treatment interval fell with increasing temperature but it could recover after treatment was removed in all periods except the first one. These results show that high temperatures during the oil accumulation phase may negatively affect olive oil yield and quality in warm regions, particularly if the high-temperature event occurs early in the phase. Additionally, the response of oleic acid concentration (%) to temperature under our experimental conditions was found to be opposite to that of many annual oil-seed crops.     

春季獭兔舍环境指标的测定与评价

獭兔是皮肉兼用型经济动物,其养殖环境直接影响獭兔生产性能。为了测定中国北方地区春季獭兔舍的环境指标,评价獭兔春季的繁殖环境状况。试验在4—5月,测定了吉林省榆树市万原兔业种獭兔舍（封闭式）内的环境指标,包括温度、湿度、风速、光照、CO2浓度及NH3浓度。测试点采用对角线取点法,水平方向取A、B、C、D、E和F六个点纵向按兔笼上中下三层各取一点,每天测三次（7:30,12:00和18:00）,共测定21天。结果表明：兔舍的环境温度为13.04℃~18.37℃;湿度在50.23%~75.73%;风速为0.05~0.09 m/s;光照为37.45~137.37 Lux;CO2浓度为0.12%~0.22%;NH3浓度为4.41~16.80 mg/m3。测试的结果反映出该兔场湿度局部偏高,畜舍光照不均,NH3超标严重,致使獭兔受凉感冒、肺炎及腹泻等疾病多发,尤其仔兔存活率仅为62.5%。经采取有效措施,如增加通风,改进光照制度和及时清粪等。环境得到了明显的改善,NH3的浓度降到4.41 mg/m3。湿度降低了3.2%~7.1%,獭兔流产死亡率显著降低了13%,獭兔总体发病率也明显改善。     

Differential heat sensitivity of two cool-season legumes,chickpea and lentil,at the reproductive stage,is associated with responses in pollen function,photosynthetic ability and oxidative damage

Increasing temperatures are adversely affecting various food crops, including legumes, and this issue requires attention. The growth of two cool-season food legumes, chickpea and lentil, is inhibited by high temperatures but their relative sensitivity to heat stress and the underlying reasons have not been investigated. Moreover, the high-temperature thresholds for these two legumes have not been well-characterised. In the present study, three chickpea (ICCVO7110, ICC5912 and ICCV92944) and two lentil (LL699 and LL931) genotypes, having nearly similar phenology with respect to flowering, were grown at 30/20°C (day/night; control) until the onset of flowering and subsequently exposed to varying high temperatures (35/25, 38/28, 40/30 and 42/32°C; day/night) in a controlled environment (growth chamber; 12 hr/12 hr; light intensity 750 µmol m⁻² s⁻¹; RH-70%) at 108 days after sowing for both the species. Phenology (podding, maturity) was accelerated in both the species; the days to podding declined more in lentil at 35/25 (2.8 days) and 38/28°C (11.3 days) than in chickpea (1.7 and 7.1 days, respectively). Heat stress decreased flowering–podding and podding–maturity intervals considerably in both the species. At higher temperatures, no podding was observed in lentil, while chickpea showed reduction of 14.9 and 16.1 days at 40/30 and 42/32°C, respectively. Maturity was accelerated on 15.3 and 12.5 days at 38/28°C, 33.6 and 34 days at 40/30°C and 45.6 and 47 days at 42/32°C, in chickpea and lentil, respectively. Consequently, biomass decreased considerably at 38/28°C in both the species to limit the yield-related traits. Lentil was significantly more sensitive to heat stress, with the damage—assessed as reduction in biomass, reproductive function-related traits (pollen viability, germination, pollen tube growth and stigma receptivity), leaf traits such as membrane injury, leaf water status, photochemical efficiency, chlorophyll concentration, carbon fixation and assimilation, and oxidative stress, appearing even at 35/25°C, compared with 38/28°C, in chickpea. The expression of enzymatic antioxidants such as superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and non-enzymatic antioxidants declined remarkably with heat stress, more so in lentil than in chickpea. Carbon fixation (assessed as Rubisco activity) and assimilation (assessed as sucrose concentration, sucrose synthase activity) were also reduced more in lentil than in chickpea, at all the stressful temperatures, resulting in more inhibition of plant biomass (shoot + roots), damage to reproductive function and severe reduction in pods and seeds. At 38/28°C, lentil showed 43% reduction in biomass, while it declined by 17.2% in chickpea at the same time, over the control temperature (30/20°C). At this temperature, lentil showed 53% and 46% reduction in pods and seed yield, compared to 13.4% and 22% decrease in chickpea at the same temperature. At 40/30°C, lentil did not produce any pods, while chickpea was able to produce few pods at this temperature. This study identified that lentil is considerably more sensitive to heat stress than chickpea, as a result of more damage to leaves (photosynthetic ability; oxidative injury) and reproductive components (pollen function, etc.) at 35/25°C and above, at controlled conditions.     

Effects of Mild Temperature Stress on Grain Quality and Root and Straw Nitrogen Concentration in Malting Barley Cultivars

Abstract It is a challenge to obtain the appropriate protein concentration in cereals for the intended end‐use. This study examined ambient temperature effects on two spring malting barley cultivars (Henley and Tipple) grown in soil or in solution culture with controlled nitrogen supply in daylight chambers with low temperature (day 18 °C, night 12 °C), and high temperature (23 °C/17 °C) to/after anthesis. In soil‐grown plants, high temperature to anthesis resulted in higher grain nitrogen amount (GNA), grain nitrogen concentration (GNC) and straw nitrogen concentration (SNC). In plants grown in solution, high temperature to anthesis resulted in lower GNA and higher GNC. A temperature rise of 1 °C during the growing period in solution cultivation increased GNC, root nitrogen concentration (RNC) and SNC, by 1.20, 1.35 and 0.33 mg g^?1, respectively. In solution culture, GNC was positively correlated with RNC and SNC (P < 0.01). Cv. Henley had higher GNC but lower SNC than cv. Tipple. Cv. Henley was more stable in grain size and cv. Tipple in GNC. The results showed that temperature has a direct effect on GNC. Accounting for temperature fluctuations up to the latest possible nitrogen fertilisation occasion can therefore help when deciding appropriate nitrogen supply for intended end‐use.     

Inheritance of the responses to a defoliation treatment affecting cold tolerance in maize

Previous studies revealed that defoliation can bring about differential responses in maize (Zea mays L.) genotypes for cold tolerance. This research was conducted to study the inheritance of the responses to defoliation for germination at low temperature and for seedling traits in early-sown field trials. Six inbred lines were crossed according to the complete diallel scheme, thus producing 36 genotypes. At milk ripening stage, half of the plants of each genotype were completely defoliated (D) whereas the other half were not (ND). Two experiments were conducted for two years, one in the germinator and one in the field. The response to defoliation was evaluated as (D–ND). Across the two years, the D treatment caused an average kernel weight decrease of ?56 mg (?23.1 % as referred to ND), an increase of 2.3 % for germination at 9 °C (G9) and a reduction of ?0.3 d for the average time of germination (ATG); in contrast, the defoliation effect was negligible for germination at 25 °C. In the field, the defoliation effects were more notable in the first (colder) year and led to an increase of 2.0 % for field emergence (FE) and to a decrease of ?2.7 g for seedling fresh weight (SFW). The genotypic variation for the (D–ND) response was significant for additive, dominance and reciprocal effects for G9, ATG, FE and SFW. There was consistency among lines across traits for additive effects, with Lo1016 and Os420 showing the best and the worst effect, respectively.     

Independent and Combined Effects of Soil Warming and Drought Stress During Anthesis on Seed Set and Grain Yield in Two Spring Wheat Varieties

Increase in soil temperature together with decrease in soil moisture during anthesis of spring wheat (Triticum aestivum L) crops is predicted to occur more frequently in a future climate in Denmark. The objective of this study was to investigate the responses of two Danish spring wheat varieties (Trappe and Alora) to soil warming (H), drought (D) and both (HD) during anthesis. The plants were grown in pots in a climate‐controlled glasshouse. In H, the soil temperature was increased by 3 °C compared with the control (C). In both D and HD treatments, the plants were drought‐stressed by withholding irrigation until all of the transpirable soil water had been depleted in the pots. Results showed that, particularly under D treatment, Alora depleted soil water faster than Trappe. In both varieties, flag leaf relative water content (RWC) was significantly lowered, while spikelet abscisic acid (ABA) concentration was significantly increased by D and HD treatments. Compared with the C plants, D and HD treatments significantly reduced ear number, ear to tiller ratio, shoot biomass, grain yield, harvest index and seed set but hardly affected tiller number and 1000‐kernel weight, whereas H treatment alone only decreased shoot biomass and reduced seed set. When analysed across the varieties and the treatments, it was found that the reduction in seed set was closely correlated with the increase in spikelet ABA concentration, indicating that D and HD treatments induced greater spikelet ABA concentrations might have caused seed abortion. It was concluded that the grain yield reduction under D and HD treatments during anthesis in spring wheat is ascribed mainly to a lowered seed set and wheat varieties (i.e. Alora) with more dramatic increase in spikelet ABA concentration are more susceptible to D and HD treatment.     

铝胁迫下大豆根尖细胞铝的微区分布与耐铝性分析

以浙春3号为实验材料, 利用透射电镜(TEM: Transmission Electron Microscope)-X-射线能谱(EDS: Energy Dispersive X-ray), 调查铝胁迫下大豆根尖铝的微区分布及耐铝性。结果表明,Al³⁺胁迫导致根尖细胞细胞壁不规则加厚, 线粒体数量增多, 核膜膨胀, 液泡中存在较多的电子致密沉淀物。90 mg L^-1 Al³⁺处理的根尖细胞内含物完全降解消失, 仅剩细胞壁。10 mg L^-1 Al³⁺处理的线粒体、细胞壁和液泡电子致密沉淀物中均检测到Al;随着Al³⁺处理浓度的增大, 各细胞器中Al的质量和原子数百分比逐渐增大。线粒体在60 和90 mg L^-1Al³⁺处理下, 液泡电子致密沉淀物在90 mg L^-1Al³⁺处理下,均未被检测出Al。在60 mg L^-1Al³⁺处理下唯一一次在细胞核中检测到Al。Al³⁺抑制了根系生长, 根系细胞中细胞壁的Al³⁺含量受影响最明显。P/Al在细胞壁和线粒体中的相对原子数随Al³⁺浓度的增大而下降。研究结果表明X–射线能谱对铝在亚显微结构上的定位是一种快速、有效的方法。铝最先积累在细胞壁上, 随Al³⁺处理浓度增大逐渐积累于部分细胞器和细胞核中, 且含量在细胞中的分布亦由外向里呈递减趁势。