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1.
Irrigation of Netted Gem potatoes was scheduled during three growing seasons by three methods: (a) when plants displayed first visual symptoms of moisture stress, (b) when indicated by a soil moisture budget involving estimated evapotranspiration, and (c) on the basis of tensiometer readings of soil moisture suction. When the tensiometer method of scheduling was used, the mean yields of tubers were 55.0 and 25.8 cwt/acre (6160 and 2890 kg/ha) higher than those obtained with the other two scheduling methods. Methods did not affect the specific gravity of potatoes. Method (a) scheduled irrigations least frequently. Scheduling by the budget method was not always adequate because it was based on the assumption that the crop extracted water from a constant 4 ft (1.2 m) profile from planting to full vegetative growth. In one year the budget method scheduled the first irrigation earlier than necessary and delayed the second irrigation during a critical period of crop growth. From full vegetative cover to harvest the irrigation schedules were alike for both the budget and tensiometer methods. 相似文献
2.
M. D. Harrison Gestur Johnson R. D. Barmington 《American Journal of Potato Research》1970,47(10):386-393
A broadcast application of PCNB (Terraclor) resulted in a reasonably uniform distribution of the chemical in the soil with the concentration decreasing in a linear fashion with increasing depth in the soil profile. A banded application resuluted in a considerably higher chemical concentration at the 4–6 inch depth than at the 0–2 or the 2–4 inch depths. The problem of the lack of uniformity of chemical distribution could probably be solved by altering nozzle placement and size and allow use of the band method of application to minimize grower cost. More complete disking in the case of the broadcast treatment would probably result in a relatively uniform distribution of the chemical but at higher cost to the grower. PCNB application rates of 10, 15 and 25 lbs per acre broadcast and 71/2, 10 and 121/2 lbs per acre in a band significantly reduced the severity ofRhizoctonia infection of Russet Burbank potatoes but did not increase potato yields significantly. 相似文献
3.
P. A. Schippers 《American Journal of Potato Research》1971,48(3):71-81
The black spot reaction was initiated by dropping plugs of varying weights from different heights onto the stem end of potatoes with known temperatures. The degree of discoloration was assessed in a scale from 0 to 5, the results were added and the sum was divided by the number of tubers. Relationships between black spot incidence, temperature and impact were very close in samples containing 100 or more tubers. This was not always the case, however, if samples were of a more manageable size of 20 to 25 tubers. Results indicated the desirability of testing under a standard set of conditions—such as 100 g falling 30 cm onto the stem end of tubers with a temperature of 10 C. The results of visual assessment of the black spots were closely related to the results of a more objective, but also more laborious, method in which the amount of discolored tissue was weighed. 相似文献
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5.
A method has been devised for assessing the potential hazard of soft rot development in potatoes. Tubers are placed in a mist chamber at 20 C (68F), a film of water is maintained on the tuber, and the extent of decay is assessed after 5 days. The soft rot potential determined in this way is intended as apractical indication of potential storage hazard, reflecting the overall effect of the various factors leading to bacterial decay. Tubers that had passed through a flume system and a rinsing spray in a commercial packing plant had a greater decay potential, even after passage through a hot-air dryer, than unwashed tubers. Differences in decay potential could be demonstrated between tubers that had been mechanically harvested and loaded into storage bins and those that had been harvested manually. In addition to the effect of mechanical damage and of passage through flumes, the decay potential was probably affected by the inoculum level ofErwinia carotovora. Pectolytic clostidia were also usually present in tubers rotting in mist chambers, and are probably involved in the decay. 相似文献
6.
Francesco Caponio Carmine SummoAntonella Pasqualone Maria T. Bilancia 《Journal of Cereal Science》2008
An experimental investigation was carried out with the aim of evaluating the effect of kneading and baking on the degradation of the lipid fraction of biscuits. For this purpose, the raw materials, the dough, and the end-products sampled during processing at a biscuit-making industrial plant were analysed. The results showed that the kneading stage caused a significant decrease in content of polyunsaturated fatty acids and a concomitant significant increase of triacylglycerol oligopolymers and oxidised triacylglycerols that are indexes of oxidative degradation. The subsequent baking step caused the degradation of part of the oxidised compounds to volatile substances, as confirmed by the determination of the p-anisidine value. On the whole, the biscuit-making process, although determining a significant increase of triacylglycerol oligopolymers, has only a small impact on the oxidation level of raw materials. 相似文献
7.
The dynamic rheological behaviours of mixtures of glutenin fractions extracted from wheat cultivar Hereward were investigated as a function of the relative concentration of high to low molecular weight glutenin concatenations. Time-temperature superposition could be applied to both the mixtures and to the total gluten, as long as heat-treated samples were distinguished from unheated samples. The ratio of high to low molecular weight concatenations was found to be very important for the rheological behaviour of the network. High molecular weight fractions promoted the network properties of the mixture, as could be seen from the presence of a plateau in the rheological spectrum. Low molecular weight fractions gave rise to a plasticizing effect as indicated by their narrowing effect on the width of the plateau region in the rheological spectrum. Upon heating, the modulus increased over the full range of frequencies, as for single fractions. This increase indicated that a thermal association occurred in the concatenations at temperatures around 40 °C. As a result of heating, the transition zone became apparent in the spectrum at high frequencies. The slopes of the loss modulus G” in the transition zone were found to be higher for mixtures rich in low molecular weight concatenations. The effect of the relative abundance of each fraction on the rheological characteristics of the mixtures was summarized in a number of simple rheological blending rules for the small-deformation rheological properties of glutenin. 相似文献
8.
Alain Le-Bail Guenaelle Leray Annick PerronnetGuillaume Roelens 《Journal of Cereal Science》2011,54(1):13-19
Breads were chilled at room temperature or using a vacuum chilling process. The staling rate was studied after partial baking and after the final baking. Vacuum chilled breads (VCBs) exhibited a higher moisture loss than conventionally chilled bread (CCB). A higher enthalpy of melting of amylopectin crystals was observed for VCB in comparison to CCB.VCB had a negative effect on the texture of the bread. The hardness of the crumb of VCB was increased by 20% at the end of staling and the kinetics of staling was 10% faster for VCB in comparison to CCB. After 12 days of storage at 4 °C, a second and final baking was applied to the bread. The staling rate of VCB was almost two times that of CCB. The staling rate of CCB was unchanged in comparison to the staling rate after partial baking. Data on the enthalpy of melting of amylopectin showed that the same amount of amylopectin was formed at the end of staling for CCB after part baked process and after full baking process. Beside, the VCB showed a higher amount of recrystallized amylopectin (10%) at the end of the staling which followed the partial baking. 相似文献
9.
中国水稻生产形势分析 总被引：14，自引：1，他引：13
对1991-2007年中国各省(区、市)水稻生产统计数据进行分析,结果表明:1991-2007年中国水稻种植面积总体呈现下降趋势,从1991年的3 259.01万hm~2下降到2007年的2 891.90万hm~2,下降幅度达到11.26%;水稻单产从1991年的5 745 kg/hm~2上升到2007年的6 433 kg/hm~2,上升幅度11.98%,单产的提高在一定程度上确保了水稻总产变化相对平稳;东部经济发达地区水稻种植面积明显下降,中部和西部变化相对平稳;南方水稻种植面积明显下降,东北地区明显上升,华北、西北地区小幅下降;南方地区单季稻比例快速上升,双改单现象明显,这是导致中国水稻种植面积下降的重要原因.要保证全国水稻生产平稳发展,重点在于稳定南方水稻种植面积,一要加大耕地保护力度,二要合理处理粮食作物与非粮食作物之间的结构调整,三是稳定双季稻种植面积.目前的工作重点是要稳定湖南、江西等水稻种植大省的双季稻种植面积. 相似文献
10.
Shinichi Nishimura Sang-bong Lee Kengo Ito Masateru Senge 《Paddy and Water Environment》2005,3(3):149-154
In the absence of a reservoir on the downstream side, a river flow that increases temporarily by rainfall cannot be stored
and discharged apart from requirements in a command area. This unused water (excess water) occurs to some extent even in a
drought year and making effective use of this supply is considered as one of the countermeasures for water shortage. Setting
up a regulating reservoir on the upstream side of head works is regarded as one of the methods for making effective use of
excess water. The inflow to the river and water delivery loss occurred from rainfall are stored in the regulating reservoir
and supplied to the command area on the downstream side as agricultural water. An operational method for the regulating reservoir
to effectively utilize the excess water was examined for a canal system by simulation. In an investigated area, there was
excess water even in drought years, and making use of it through the regulating reservoir whose capacity is smaller compared
to that of a dam can become one of the countermeasures for the drought period. The simulation in this study could estimate
quantitatively the effect of the regulating reservoir to make the excess water effective. 相似文献
11.
Strategies based on using the translaminar fungicide cymoxanil for control of potato late blight, caused by Phytophthora infestans, were compared in the highland tropics of Ecuador in three separate field experiments. In one strategy, a commercial formulation of cymoxanil mixed with mancozeb was sprayed sequentially three times early in the season; this was then followed by three sequential sprays of a commercial product containing mancozeb alone. For the other strategy, the same commercial products were alternated. For each strategy, a spray interval of 14 d was used after the contact/translaminar mixture and 10 d after sprays containing mancozeb alone. Both strategies were evaluated with a manually operated knapsack sprayer but with two levels of application quality. High quality was achieved with a constant pressure valve and a new nozzle, while for low quality, fungicide was applied without a valve and using a damaged nozzle. All treatment combinations gave adequate disease control and no consistent effect of application strategy or application quality could be measured on disease severity or yield. However, approximately twice the volume of fungicide was applied using poor quality equipment, regardless of the application strategy. Advantages and disadvantages of the strategies and their potential effects on fungicide resistance are discussed. 相似文献
12.
栽培稻分类方法的比较 总被引：18，自引：3，他引：18
为了比较Glaszmann和程侃声等对亚洲栽培稻的分类体系,将Glaszmann氏提供的197个水稻品种的同功酶位点原始记录和程氏对它们就6个形态性状的评分作了主成分分析和聚类分析。结果显示二人的分类基本一致,数值分类也表明栽培稻可以只分籼粳两个亚种,处于中间的少数品种可称为偏籼或偏粳。程氏采用的“性状指数法”似更为便利而有效,特别适于田间及育种工作,虽然带有一定的经验成分,但加以生化或数值分类的检验,即可弥补该法的不足,有助于澄清个别不够明确和错划的事例。因此,我们建议为求得最佳的分类系统,最好运用二种以上的方法,相互补充校正。 相似文献
13.
Mullie P Clarys P Deriemaeker P Hebbelinck M 《Plant foods for human nutrition (Dordrecht, Netherlands)》2007,62(3):93-98
The daily intake of food flavonoids was determined using a semiquantitative food frequency questionnaire (FFQ) and a four day non consecutive food diary (4DFR) in a group of 45 female Flemish dietitians. The subjects were asked to report their food intake three times: day 1 using the FFQ (FFQ1); between day 2 and 13 using a four day non consecutive food diary (4DFR); and again the FFQ on day 14 (FFQ2). The total flavonoid intake in mg/day as estimated with the different methods were respectively (mean and SD) for FFQ1 166.0 +/- 146.6 mg/day; for 4DFR 203.0 +/- 243.2 mg/day; and for FFQ2 158.3 +/- 151.8 mg/day. There was a significant different estimate for the amount of flavan-3-ols, flavanones and flavones when comparing the two FFQs with the 4DFR. The two research methods classified 88% of the 45 dietitians in the same or in an adjacent quartile for total flavonoid intake. The findings of this study indicate that the developed FFQ seems to be a simple and reliable method to assign subjects in quartiles of flavonoid intake. 相似文献
14.
水合氧化铁提前施用对持续淹水条件下水稻甲烷的减排效应 总被引：1，自引：0，他引：1
水合氧化铁是一种弱晶质三价铁氧化物,可用来减少稻田甲烷（CH4）的排放。采用水稻盆栽试验,研究水合氧化铁的提前施用对持续淹水条件下水稻CH4排放的影响。结果表明:水合氧化铁在水稻移栽前47 d施用,加Fe处理的全生育期CH4总排放通量比对照减少17.52%,其CH4减排效应仅出现于水稻生长后期。在移栽后第70天,加Fe处理的根孔隙度、根表铁膜含量和单株根表铁膜数量均显著高于对照,而稻根产CH4速率则显著低于对照。因此,提前施用水合氧化铁能够通过促进植株介导的根表铁膜的形成抑制稻根的产CH4潜力,进而实现持续淹水条件下水稻CH4的减排。 相似文献
15.
To use common differential varieties in the world, a set of international differential varieties, including 6 indica and 2 japonica rice varieties, were set up in the middle of 1960s; in 1976, a set of differential varieties composed of 9 japonica varieties with known resistance gene were established; 相似文献
16.
波罗蜜叶片突变体叶绿素含量测定和超微结构观察 总被引：1，自引：0，他引：1
波罗蜜（Artocarpus heterophyllus）是一种热带果树,至今对其突变体的研究少有报道。本研究以波罗蜜叶片为试验材料,探究其叶片出现白化和返绿现象的可能原因。（1）用分光光度计法、比色法测定波罗蜜叶片突变体和正常绿叶的叶绿素及叶绿素前体物质含量;（2）用叶绿素酶Elisa试剂盒测定叶绿素酶活性;（3）用透射电子显微镜对叶绿体的超微形态结构进行观察。研究结果表明：（1）不同叶色所产生的叶绿素a含量、叶绿素b含量、叶绿素总含量、类胡萝卜素含量均存在显著差异;（2）波罗蜜叶片突变体和正常绿叶的叶绿素合成前体物质含量之间并没有出现显著性差异;（3）对波罗蜜叶片的叶绿素酶活性进行测定时,发现其活性出现显著差异,但对其叶绿素含量的差异性并没有产生较大影响;（4）观察波罗蜜叶片内叶绿体超微形态结构时,发现正常绿叶的叶绿体形态完好且数量较多,白化叶和返绿叶的叶绿体内部结构存在缺陷,其原因是叶绿体基粒构建阶段受阻;基于测定波罗蜜叶片中的叶绿素、叶绿素前体物质含量和叶绿素酶活性,并观察波罗蜜叶片内叶绿体的超微形态结构,对得到的数据结果进行比较分析。本研究推测是在叶绿素合成阶段,原脱植基叶绿素合成叶绿素时受阻及叶绿体发不良导致波罗蜜出现白化和返绿现象,为今后进一步综合研究波罗蜜突变体提供理论依据。 相似文献
17.
The present study aims at characterizing and modeling the anisotropic creep behavior of coated textile membrane, a class of
flexible textile composites that are used for moderate span enclosures (roofs and air-halls). The objective is to develop
a creep model for predicting the lifetime of coated textile membrane. Uniaxial creep tests were conducted on three off-axis
coupon specimens to obtain the directional creep compliance. A potential with three parameters is shown to be adequate for
modeling the anisotropic creep behavior of coated textile membrane. Furthermore, a possibility of predicting the creep deformation
of coated textile membrane in a multi-axial stress state is discussed using the three-parameter potential. 相似文献
18.
2006年初,中国热带农业科学院科研基地的院试验场下属的原宝岛公社5个单位的生产队(村)以多种方式要求退出试验场编制,严重影响了中国热带农业科学院科研事业的发展。院国有资产管理处经过一年多的详细调查,认真分析了中国热带农业科学院试验场土地管理中存在的问题,提出一些解决对策,以期探讨新形势下切实可行的科研基地管理模式。 相似文献
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The effects of 60Co gamma-irradiation treatments (2·5, 5·0, 10·0 and 20·0 kGy) on the gluten proteins of two bread wheats and one durum wheat cultivar were investigated. Dough rheological properties of the flour processed from the irradiated wheat were also determined using a computerised micromixograph. Irradiation caused a significant deteriorating effect on all mixogram parameters. There was no observable effect of irradiation on gliadin proteins analysed by polyacrylamide gel electrophoresis. The 50% 1-propanol-insoluble (50 PI) glutenin fraction was highly affected by irradiation. By sodium dodecyl sulfate polyacrylamide gel electrophoresis, reduced 50 PI glutenin showed a noticeable reduction in band intensities of both high (HMW) and low molecular weight (LMW) glutenin subunits (GS) with increasing irradiation dosage greater than 5 kGy. The irradiation effect on 50 PI glutenin was further studied and quantified by reversed-phase high-performance liquid chromatography of glutenin subunits; there was a progressive decrease in the quantity of subunits with increasing irradiation dose level. Compared to non-irradiated wheat, the relative decline in total insoluble glutenin at the 20 kGy dosage level ranged from 34–49% depending on cultivar. Increasing levels of irradiation also progressively reduced the ratio of HMW:LMW-GS up to 13–15% at 20 kGy indicating that irradiation had a greater effect on the largest polymers of glutenin. The observed weakening of dough mixing properties and concomitant decline in the quantity of 50 PI glutenin with increasing levels of gamma-irradiation are consistent with a degradation of glutenin to a lower average molecular size by depolymerisation and/or disaggregation. 相似文献