A Comparison of Plant Temperatures as Measured by Thermal Imaging and Infrared Thermometry

The temperature of leaves and canopies of plants has long been recognised to be an indicator of plant water stress and can be assessed by thermometry or thermography. Considerable research has been carried out with each of these techniques individually; however, a comparable assessment has not been done to the best of our knowledge. Therefore, we compared the potential of high‐resolution thermography and infrared (IR) thermometry to discriminate among stress treatments (control, drought, salt and combined salt and drought) and cultivar effects in large container‐based experiments that mimicked field conditions. Differences among treatments and between cultivars, with differences varying between 1–9 and 0–2 °C, respectively, were in dense crop stands comparably well ascertained by IR thermometry and thermography. Both methods allowed discriminating differences in salt tolerance. Interestingly, enough similar results were observed for processed, by unmixing the soil influence, and unprocessed thermal images at soil coverage higher than 60 %. Using thermography and IR thermometry, highly significant and close relationships were established between canopy temperature and leaf water potential. Overall, in this study, the more simplistic technique based on IR thermometry performed in dense crop stands similarly well as the more sophisticated method provided by thermography.     

不同耐旱性青稞叶片差异蛋白分析

为从蛋白质水平揭示不同青稞品种响应干旱胁迫的差异,分析抗旱蛋白质分子机制,本研究以干旱胁迫不敏感的旱地紫青稞(HDZ)和干旱胁迫敏感的大麻青稞(DM)为研究材料,以盆栽限量供水种植方法,对干旱处理不同梯度的青稞叶片进行叶绿素、可溶性蛋白、丙二醛含量及相对电导率4项生理指标的测定,同时利用iTRAQ技术对深度干旱胁迫青稞叶片全蛋白组进行差异蛋白分析。结果表明:随着干旱处理时间的延长,两种青稞的叶绿素和可溶性蛋白含量逐渐下降,电导率及丙二醛的含量逐渐升高,在相同处理条件下,大麻青稞的叶绿素和可溶性蛋白含量降低幅度、电导率及丙二醛含量的增高幅度明显高于旱地紫青稞;对两个青稞品种的干旱胁迫和正常培养的比较组进行iTRAQ分析,共定量出4163个蛋白(多肽),其中旱地紫青稞比较组中对比正常培养,筛选到表达上调的蛋白68个,下调的蛋白63个,在大麻青稞的比较组中筛选出表达上调蛋白21个,下调蛋白32个。KEGG通路分析表明,富集程度位于前3位的通路是代谢、氨基酸的生物合成以及次级代谢产物的生物合成,主要涉及到柠檬酸循环、碳循环等代谢通路,丙氨酸、精氨酸等氨基酸的合成降解以及花生四烯酸、亚麻酸等次级...     

Atmospheric humidity and genotype are key determinants of the diurnal stomatal conductance pattern

Great understanding of the genotypic difference in diurnal stomatal conductance (g_s) pattern and the key determinants of the pattern is important for saving water by adopting cultivars appropriately. Fifteen wheat genotypes were studied under different soil conditions and various meteorological conditions with pot cultivation in rain shelter for two years. Genotype and air humidity were found to be key determinants of diurnal g_s pattern. All genotypes under low relative humidity (LRH) and most genotypes under high relative humidity (HRH) displayed a gradual decline pattern from morning through the afternoon. Under moderate relative humidity (MRH), all genotypes present a single-peak curve pattern, but they differed in peak time, which may lead to unreliable g_s comparison between genotypes and get ostensible contrasting materials. The stomatal conductance was significantly different among genotypes under LRH and the increased g_s magnitude is also significantly different when it was compared between LRH and HRH. The present results provide new thinking for selecting and adopting appropriate cultivars with specific stomata traits for the area with various meteorological conditions.     

A study of grain dormancy and viability in spring barley

In field experiments carried out between 1989 and 1991, spring barley was sampled to observe changes in the grain viability and dormancy during grain filling. The weather during the grain filling periods of 1989 and 1990 was unusually warm and dry, and the crop in 1989 was affected by drought. Some grains were capable of germination shortly after anthesis, but were dormant. Dormancy declined with increasing maturity, but was prolonged by low temperatures and reduced by warm weather. Differences were found in the dormancy characteristics of the two cultivars tested. Apart from grains at the extremities of the ear, which were sometimes found to be small and with low viability and greater dormancy, though not significantly so, no consistent differences were found between the viability and dormancy of grains in different positions in the ear.     

Selection environment and environmental sensitivity in barley

Summary Groups of 10 barley genotypes were selected for high grain yield under either high yielding (two groups) or low yielding conditions (two groups). The genotypes had a similar average grain yield across a wide range of yielding conditions, but differed in their linear response over environments (environmental sensitivity). The genotypes selected for high grain yield under low yielding conditions were less sensitive to changing environments than genotypes selected for high grain yield under high yielding conditions. The higher stability of genotypes selected under low yielding conditions was shown by both the linear regression analysis and the comparison of coefficients of variation. The use of a safety-first index showed that the probability of a crop failure of genotypes selected for high grain yield under high yielding conditions was between 1.8 and 2.7 times higher than for genotypes selected for high grain yield under low yielding conditions. The development of new cultivars for areas where a large proportion of the crop is grown by subsistence farmers should therefore be based on selection under low yielding conditions.     

Grain yield and its components in spring barley under row and hill plot conditions

Twenty homozygous barley lines were grown in row and hill plots at two locations in Ontario in 1973. The hill plots were of two spacings –30×30 cm and 45×45 cm between hills. Within each spacing, three seeding rates were used i.e. 15, 25 and 35 seeds per hill. Grain yield and three of its components, namely; number of seeds per spike (NSS), number of spikes per plot (NSP) and seed weight (SW) were studied. It was concluded that both NSS and SW could be evaluated in hill plots. NSS was found to be an important component of grain yield and its relationship with grain yield was unaffected by plot types and locations. SW also remained unaffected by plot types and seeding rates but as a component of grain yield it was the least important of the three components measured. The correlation between SW and grain yield could be changed by locations. NSP was as important as NSS as a component of grain yield, and was highly correlated with grain yield. Unlike NSS, NSP could not be efficiently evaluated in hill plots since its correlation between row and hill plots was generally lower.     

Evaluation of barley yellow dwarf tolerance from plant traits in two winter × spring barley crosses

Summary Winter-type experimental lines from crosses of two winter-type barley cultivars with a spring-type, barley yellow dwarf (BYD) tolerant cultivar were compared in inoculated and uninoculated hill plots. Mature plants traits-winter survival, height, number of spike-bearing tillers, and biomass-were examined. The experimental lines could not be compared with the BYD tolerant parent using these diagnostic symptoms since the spring-type parent would be winterkilled. Two criteria were used to rate experimental lines for BYD tolerance: (1) nonsignificant difference between BYD-inoculated and BYD-uninoculated treatments for all traits, and (2) a BYD injury score obtained by averaging percent reduction from BYD infection for each trait.Missouri Agricultural Experiment Station Journal Paper No. 10059. This research supported in part by Anheuser-Busch, Inc, St. Louis, MO, USA.     

亚精胺处理青稞幼苗对NaCl胁迫作用的缓解

以青稞（Hordeum vulgare L. var. nude）幼苗叶片为试材,以200mmol/L NaCl对其进行盐胁迫,研究了外源亚精胺（Spd）预处理对NaCl胁迫下青稞幼苗叶片相对含水量（RWC）、叶绿体色素与水溶性蛋白质含量的影响。在NaCl胁迫的前两天,NaCl+Spd处理组用含0.5mmol/L Spd的1/2Hoagland营养液进行水培和叶面喷施含0.02%土温-80的0.5mmol/L Spd溶液;对照组（CK）和NaCl处理组,用1/2的Hoagland营养液进行水培,叶面喷施含0.02%土温-80的蒸馏水。随着200mmol/L NaCl胁迫的进行,青稞幼苗叶片RWC、叶绿体色素与水溶性蛋白质含量均明显降低,Spd预处理显著延缓了它们的下降。表明Spd预处理缓解了NaCl胁迫对青稞幼苗造成的伤害,具有防衰抗盐的保护作用     

Possibility of exploiting the Yd2 resistance to BYDV in spring barley breeding

The effects of the Yd2 gene on tolerance to barley yellow dwarf virus (BYDV) and other agronomically important characters in spring barley were evaluated in a set of randomly selected doubled haploid (DH) lines of an‘Igri’/‘Atlas 68’ cross and three crosses between CIMMYT Yd2 materials and the Czech malting barley ‘Akcent’. The cleaved amplified polymorphic site (CAPS) diagnostic marker Yd2 was used for identification of the Yd2 gene and this analysis showed high agreement with the results of field infection tests. Yd2 lines exhibited significantly lower symptom scores and lower reductions of some grain yield characters, but their resistance level was not consistent over the years. The presence of secondary stresses (high temperature/drought) in 2000 led to relatively higher sensitivity to BYDV infection, strengthened by the long life cycle of genotypes. In cases where secondary stresses were mild (in 2002), the longer life cycle significantly increased sensitivity to BYDV infection only in the absence of the Yd2 gene (in susceptible genotypes). The examination of different vegetative, grain yield and malting quality characters separately for groups of Yd2 and non‐ Yd2 lines did not show any evidence of adverse effect of the Yd2 gene on any character.     

Infrared Thermal Imaging as a Rapid Tool for Identifying Water‐Stress Tolerant Maize Genotypes of Different Phenology

The main task of this research was to evaluate canopy temperature and Crop Water Stress Index (CWSI) by assessing genotype variability of maize performance for different water regimes. To that end, three hundred tropical and subtropical maize hybrids with different phenology in terms of date of anthesis were evaluated. The influence of phenology on the change in canopy temperatures and CWSI was not equal during the three dates of measurement. At the end of vegetative growth (82 days after sowing, DAS) and at the blister stage (DAS 97), a high significant difference in temperatures and CWSI (P < 0.001) were obtained between the early‐ and late‐maturity genotypes. During anthesis (DAS 89), phenology had a significant effect (P < 0.01) only for the well‐watered genotypes, while under water‐stress conditions, no differences were found between early and late genotypes in terms of canopy temperature and CWSI. High significant differences (P < 0.001) in stomatal conductance (g_s) between early and late genotypes for different treatments were observed. A relationship (R² = 0.62) between g_s and canopy temperature was obtained. Under a water‐stress canopy, temperature was measured at anthesis, which was negatively correlated with grain yield of the early (r = ?0.55)‐ and late (r = ?0.46)‐maturity genotypes in the water‐stressed condition.     

大麦种质资源成株期抗旱性鉴定及抗旱指标筛选

干旱是影响大麦生产的主要因素之一。在鉴定大麦种质资源成株期抗旱性的基础上,筛选抗旱指标,可为培育抗旱品种提供依据。本研究在2016和2017年在大麦生长主要需水期平均降雨量不足40 mm的甘肃省武威市进行田间试验,以30份大麦种质资源为研究对象,设置正常灌水和干旱胁迫处理,测定大麦株高、穗长、分蘖数、单株粒数、单株粒重、穗粒数、千粒重和产量,采用抗旱性度量值(D)、综合抗旱系数(CDC)、加权抗旱系数(WDC)、相关分析、频次分析、主成分分析、灰色关联度分析、隶属函数分析、聚类分析和逐步回归分析相结合的办法,对其进行抗旱性鉴定及抗旱指标的筛选。干旱胁迫对测定的各指标均有极显著影响。频次分析表明,各指标对干旱胁迫反应的敏感程度依次为产量、株高、单株粒重、穗长、单株粒数、分蘖数、穗粒数和千粒重。相关分析表明,产量与株高、穗长、分蘖数、单株粒数和单株粒重呈极显著正相关,与穗粒数呈显著正相关、与千粒重呈不显著正相关。主成分分析表明,5个主成分可以代表大麦抗旱性86.39%的原始数据信息量。基于D值、CDC值和WDC值的大麦种质资源抗旱性排序基本一致。灰色关联度分析表明,各指标单项抗旱系数值与D值间的关联度依次为产量、单株粒重、单株粒数、穗长、株高、分蘖、穗粒数和千粒重,各指标DC值与WDC值间的关联大小依次为单株粒重、产量、单株粒数、分蘖、穗长、穗粒数、株高和千粒重。根据D值进行聚类分析,将供试大麦种质资源依据抗旱性从强到弱分为5个抗旱等级,其中1级5份、2级1份、3级11份、4级10份、5级3份。除分蘖和千粒重外,其余指标的隶属函数值、CDC值、D值和WDC值均随着抗旱级别的升高而增大。回归分析表明, 5个测定指标均与D值密切相关。干旱胁迫对大麦种质资源成株期各指标均有极显著影响。确定了D值为适宜的抗旱鉴定指标。筛选出成株期抗旱性强的大麦种质资源甘啤7号、Z06-278-9、MERIT、NEVADA和西藏25,可为大麦抗旱育种、抗旱机制以及干旱调控缓解机制的研究提供技术支持。穗长、单株粒数、单株粒重、穗粒数、产量可作为大麦种质资源成株期简单、直观的抗旱评价指标。     

Prediction of grain protein in spring malting barley grown in northern Europe

The ability to predict grain protein concentration at harvest (CP) in Swedish malting barley (Hordeum distichum) from observations of soil conditions, sowing day, fertilisation rate, remote sensing at early stem elongation and the temperature sum during grain filling, was tested for two cultivars; Astoria (Secobra, France) and Wikingett (Svalöf-Weibulls, Sweden) in 16 fertilisation trials in southern Sweden, encompassing 3 years (2001–2003). Fertilisation was applied either as a single dose at sowing, or as both a starting application and an application at early stem elongation. The highest total application rate was 160 kg N ha⁻¹ y⁻¹. The soil was analysed for phosphorus, potassium, magnesium and calcium in the layer 0–0.3 m, and mineral N down to 0.6 m. Canopy reflectance observations at BBCH 32 was used to calculate a vegetation index (TCARI(32)) to reflect the canopy (leaf and straw) chlorophyll concentration. Harvested grain CP correlated only marginally with the observed soil variables. It was, however, for a specific cultivar, possible to make a prediction of grain CP based on day of sowing and TCARI(32) with . Part of the sowing day effect might be due to thermal stress during grain filling, as the risk for high temperatures during this phase was higher when sowing was late. This might also explain why the introduction of accumulated temperature during grain filling, into a model already including sowing day and TCARI(32) as independent variables, did not improve the predictability of grain CP.     

Molecular mapping of QTLs for non-parasitic leaf spot resistance and comparison of half-sib DH populations in spring barley

Quantitative trait loci (QTLs) for resistance against non-parasitic leaf spots (NPLS) were first characterized in a spring barley double haploid population derived from the cross IPZ 24727/Barke (Behn et al., 2004). The aim of the present study was to identify QTLs for NPLS resistance in the half-sibling DH population IPZ 24727/Krona and to compare them with the QTLs of the population IPZ 24727/Barke. An anther culture-derived doubled haploid population of 536 DH lines was developed from the cross IPZ 24727 (resistant)/Krona (susceptible). Field trials were performed over two years in two replications, scoring NPLS and agronomic traits that might interact with NPLS. A molecular linkage map of 1035 cM was constructed based on AFLPs, SSRs and the mlo marker. QTL analyses for NPLS identified three QTLs that accounted for 30% of the phenotypic variation. For comparison of the QTLs from each DH population, a consensus map was generated comprising 277 markers with a length of 1199 cM. In both populations, the QTLs for NPLS mapped to chromosomes 1H, 4H and 7H. A common QTL with a great effect in both populations and over all environments was localized at the mlo locus on chromosome 4H, indicating that the mlo powdery mildew resistance locus has a considerable effect on NPLS susceptibility. The steps necessary to validate the QTLs and to improve the NPLS resistance by breeding were discussed.     

Inheritance of gramine content in barley

The inheritance of gramine indole alkaloid was studied in F1 and F2 generations derived from crosses between wild ( Hordeum vulgare subsp. spontaneum) and cultivated ( H. vulgare subsp. vulgare) barley at adult stage in the field. The means of gramine content were very low in F1s and F2s in April and May. The ratio of progeny containing gramine to those without gramine (near zero or undetectable) fit a mono-genic or di-genic model in F2 generation. However, the content of gramine might be controlled by minor genes in the gramine-containing plants. The direction of dominance was toward lower gramine content. The averages of dominance ( h/d) in F1 and F2 ranged from partial to complete. Broad-sense heritabilities were high (0.70 to 0.77). The usefulness of hybrids for breeding aphid resistance and possibility increasing palatability of grazing pasture for sheep and cattle is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Molecular adaptation of barley to cold and drought conditions

Summary Molecular adaptation to cold and drought involves a series of biochemical and molecular changes leading plants to improve their winter hardiness or drought resistance.We are interested to study the molecular basis of cold acclimation and drought response of barley to survive under stress. Several genes regulated by low temperatures and sometimes by drought have been isolated from the barley genome. In this review the most significant results of our recent work will be presented and discussed.The protein encoded by cDNA clone pt59 and induced in barley by cold was over-expressed in E. coli to produce the matching antibody, which in vivo recognizes a cold-induced protein of 14 kDa (COR14). The COR14 is stored in amounts only slightly greater in the cold resistant Onice than in the susceptible Gitane, although the former has a higher induction-temperature threshold of COR14 than the latter. This fact is an evolutionary advantage enabling the resistant varieties in the field to prepare for the cold well ahead of the susceptible ones.Two other cDNA clones, paf93 and cdr29, are regulated by low temperature and drought stress but not by exogenous ABA treatment. Indeed during the early stage of dehydration, the mRNAs are expressed before the induction of known ABA regulated genes such as dehydrins and when only a small increase occurs in ABA content. The sequence analysis revealed that paf93 encodes for a protein homologous to the cold-regulated protein COR47 of Arabidopsis, whereas cdr29 represents a plant gene homologous to yeast and mammalian sequences coding for acyl-Coenzyme A oxidase.Abbreviations ABA abscisic acid - COR cold regulated     

Rapid phenotyping of adult plant resistance in barley (Hordeum vulgare) to leaf rust under controlled conditions

Breeding for adult plant resistance (APR) is currently impeded by the low frequency of annual field‐based testing and variable environmental conditions. We developed and implemented a greenhouse‐based methodology for the rapid phenotyping of APR to leaf rust in barley to improve the efficacy of gene discovery and cloning. We assessed the effects of temperature (18 and 23°C) and growth stage (1–5 weeks) on the expression of APR in the greenhouse using 28 barley genotypes with both known and uncharacterized APR. All lines were susceptible in week 1, while lines carrying Rph20 and several with uncharacterized resistance expressed resistance as early as week 2. In contrast, lines lacking Rph20 and carrying either Rph23 and/or Rph24 expressed resistance from week 4. Resistant phenotypes were clearest at 18°C. A subset of 16 of the 28 lines were assessed for leaf rust across multiple national and international field sites. The greenhouse screening data reported in this study were highly correlated to most of the field sites, indicating that they provide comparable data on APR phenotypes for screening purposes.     

Fungal Endophytes Enhance Agronomically Important Traits in Severely Drought‐Stressed Barley

Crops often face severe and damaging local drought events, and in some regions, these episodes are predicted to become more frequent due to climate change. Some micro‐organisms have been shown to improve drought tolerance and improve yield in crop plants. Here, we show that fungal root endophytes isolated from a wild barley species (Hordeum murinum subsp. murinum) induced significant improvements in agronomic traits for a severely drought‐stressed barley cultivar grown in a controlled environment, including number of tillers, grain yield and shoot biomass. Five endophyte strains were tested, and the trait that showed the greatest significant difference in the drought‐stressed plants was the number of tillers, where all of the endophyte treatments induced a greater number of tillers per plant. However, except in one case, the mean dry root weight for all plants was greater in the control plants, indicating preferential allocation of resources to aboveground parts in the endophyte treatments. Results were not consistent across all endophyte treatments, with some endophytes performing much better than others. As these growth studies were conducted using soil‐based compost, the results may translate to the field and suggest that some of these endophytes have potential as barley inoculants in arid growing conditions.     

Genetic improvement of spring barley cultivars grown in eastern Canada from 1910 to 1988

Summary Spring barley is an important feed crop in eastern Canada, and the development of high-yielding, high grain protein cultivars is desirable. This study was conducted to assess the impact of breeding on the yield and protein aspects of cultivar development, and to identify related changes in plant characteristics which may have been altered over time. A 3-year field experiment was conducted to evaluate twenty six-rowed spring barley genotypes representing the majority of cultivars developed from 1910 to 1988 for eastern Canada. The yields of barley cultivars released from 1935 to 1988 increased at a rate of about 0.03 t ha^-1 yr^-1, and showed no evidence of having reached a plateau. Increases in yield were associated with higher total dry matter production and harvest index, reduced plant height and increased lodging resistance. No consistent change in main stem or tiller yield components was observed. Grain protein concentration decreased progressively with time, especially with the newer cultivars. Reduction in grain protein concentration was not associated with lower protein content on a per grain basis, but rather with an increase in the amount of non-structural carbohydrate per grain. Total plant and grain N accumulation showed positive trends with time. No trends were observed for N harvest index, apparent post-heading N uptake, N retranslocation, and retranslocation efficiency. Thus, while the newer cultivars accumulated more total and grain N, proportional N partitioning to the grain was not altered.