Winter Hardiness in Faba Beans: Varietal Differences and Interrelations among Selection Criteria

Nine European varieties of winter beans (Vicia faba L- var. minor and equina), pre-germinated at 20°C and raised at 15°C until plant emergence, were hardened at 8/2°C (day/night) for severals week;, and then “dehardened” at 15°C or 10°C. Development and varietal expression of freezing resistance (FR). und of several characters generally supposed to be linked with winterhardness, were examined during hardening and dehardening. Alter 5 weeks of hardening, most leaf traits remained constant while growth of plants and development of new leaves continued slowly. At the onset of dehardening FR and DM-content of tissue decreased, whereas most traits increased, rapidely or were enhanced considerably resulting in positive or negative phenotypical correlations of the traits with FR. With respect to winterhardiness, the old French landrace ‘Cote d'Or’ had the most advantages for almost each trait compared to the other varieties tested, Genotypic correlations established among leaf and plant traits, and with FR, might allow a limitation of the number of selection criteria for winterhardness. Even the laborious determinations of FR. might be omitted or minimized, since its genotypic variation was determined to 64 % by the variation in the rate of development, the change in height and water/D:M- ratio, and the leaf area. The validity of a winterhardness ideotype and the restrictions which havt1 to be considered with respect to the measurement of the proposed selection criteria are discussed.     

低温对不同土壤湿度下小麦植株性状和产量影响研究

为研究小麦在不同土壤湿度下经受低温冻害后植株性状和产量变化规律,以‘周麦22’为研究对象,研究了拔节期小麦在-6℃（植株体温度）低温环境下维持4 h,土壤重量含水量为26%、18%、10%时,小麦后期植株性状和产量的变化。研究结果显示：随着土壤重量含水量的增加,低温冻害对小麦株高、最低茎高、穗下节长、倒二节长和生物产量的影响逐渐降低,土壤重量含水量接近10%时,小麦植株性状则显著降低。随着土壤重量含水量的增加,低温冻害对小麦产量的影响逐渐减轻,土壤重量含水量接近18%时,小麦产量则显著降低,且低温对不同土壤重量含水量环境下小麦穗粒数影响大,对穗数和千粒重影响较小。低温处理后不同土壤湿度处理之间,处理W（土壤含水量26%）、处理M（土壤含水量18%）、处理D（土壤含水量10%）和CK潜蘖穗数差异显著(P<0.05),处理W、CK和处理M、处理D之间大穗产量存在显著差异(P<0.05),其余处理之间均差异不显著。该试验为预防和降低小麦低温灾害及小麦生产提供技术帮助。     

Genetic studies of antifreeze proteins and their correlation with winter survival in wheat

Antifreeze proteins (AFPs) accumulate in the leaves of winter cereals during cold acclimation, where they may inhibit ice recrystallization during freezing and thawing cycles and provide nonspecific disease resistance. In this study, 21 wheat chromosome substitution lines and the parental lines Chinese Spring and Cheyenne wheat were used to determine the heritability of AFPs and the relationship between the accumulation of AFPs and winter survival. In cold-acclimated lines, antifreeze activity in leaf apoplastic extracts ranged from 1 (low) to 5 (high) with an average value of 3.2, and the accumulation of apoplastic proteins ranged from 30 μg (g FW)^-1 to 115 μg (g FW)^-1 with a mean value of 70 μ (g FW)^-1. Examination of the individual lines revealed that Cheyenne chromosomes 5B and 5D carry major regulatory genes that increase both antifreeze activity and the accumulation of antifreeze proteins in plants grown at low temperature. Substitution lines carrying Cheyenne chromosomes 2A, 3A, 6B, and 7A exhibited lower freezing tolerance and also showed a marked decrease in the accumulation of specific AFPs during cold acclimation. Antifreeze activity and apoplastic protein content were not correlated with freezing tolerance (defined as % survival at -11 °C), but they were both significantly and positively correlated with winter field survival rates. Antifreeze activity (positively correlated) and total leaf fresh weight (negatively correlated) together accounted for about 55% of the variation in winter survival, indicating that high antifreeze activity and slow vegetative growth at low temperature are both important quantitative traits for winter survival. This revised version was published online in July 2006 with corrections to the Cover Date.     

小麦灌浆期不渍和高温对植株早衰和籽粒增重的影响

用3种土壤湿度、2种空气温度研究了10个小麦品种对灌浆期水渍和高温的反应。结果表明，在湿和热二种因素中，湿害对叶片枯衰、穗部失水和百粒重降低影响甚大，而高温的影响相对较小，湿热互作效应显著。小麦品种对高温水渍处理的反应也有时显差异，这种差异主要是由品种间耐湿性不同造成的，品种间耐热性差异也有关系，但品种     

Frost resistance of 'Chinese Spring'/'Cheyenne' chromosome substitution lines under short- and long-day hardening conditions

Investigations were carried out under phytotronic conditions to study the effect of daylength on the frost resistance of a ‘Chinese Spring’/‘Cheyenne’ chromosome substitution series. The frost resistance of the 5A, 7A, 4B, 5B, 1D and 5D lines was significantly better when raised and hardened with long-day (16 h) rather than short-day (8h) illumination. The frost resistance-increasing effect of daylength could be demonstrated after freezing lines 5A and 5D at both - 10°C and -12°C. An increase in the duration of illumination in the course of preliminary growth and hardening promoted the development of a higher level of frost resistance. This positive effect was most pronounced for chromosome substitution lines, where the frost resistance was significantly better than that of ‘Chinese Spring’ even with normal daylengths.     

Drought and heat stress reduce yield and alter carbon rhizodeposition of different wheat genotypes

Drought and high temperature are major environmental stress factors threatening wheat production during grain filling stage resulting in substantial yield losses. Four wheat genotypes (Suntop, IAW2013, Scout and 249) were planted under two temperature levels (25 and 30°C) and two water levels (15% and 25% soil moisture content). Wheat yield, leaf δ¹³C, plant rhizodeposition, shoot biomass and root traits were examined. Low moisture (drought stress) and high temperature (heat stress) decreased the grain yield of all wheat genotypes, in particular 249, while combined drought and temperature stresses had the most pronounced negative effect on plant biomass and grain yield. Decreasing soil water availability decreased the allocation of plant‐derived C to soil organic carbon (SOC) and to microbial biomass through rhizodeposition. Leaf δ¹³C decreased with increased yield, suggesting that higher yielding genotypes were less water stressed and allocated less C to SOC and microbial biomass through rhizodeposition. Wheat genotypes with lower root/shoot ratios and thinner roots were more efficient at assimilating C to the grain, while genotypes with higher root/shoot ratios and thicker roots allocated more C belowground through rhizodeposition at the expense of producing higher yield. Therefore, improving these traits for enhanced C allocation to wheat grain under variable environmental conditions needs to be considered.     

A Genetic Study of Frost Resistance in Wheat Callus Culture

The genetic control of frost resistance was studied in callus cultures using some of the chromosome substitution lines of the variety ‘Cheyenne’ into ‘Chinese Spring’. The survival of the calli derived from immature embryos was studied with triphenyltet-razolium chloride (TTC) and fluorescein diacetate (5DA) methods after hardening and freezing at a temperatures of -7 °C, -9 °C, -11 °C, -13 °C, and –15 °C. The donor ‘Cheyenne’ and the substitution lines 5A and 5D proved to be more frost resistant than the recipient ‘Chinese Spring1. These results are well correlated with the previously published studies when seedlings were tested under controlled conditions. Based on these results the tissue culture technique seems to be useful for testing varieties and lines for different levels of frost resistance and even for mutant selection.     

A Rapid Method for Measuring Freezing Resistance in Crop Plants

The objective of this study was to develop a technique based on chlorophyll fluorescence to assess freezing injury and resistance of leaves. Optimization was done with faba bean leaves and applicability to other crops was examined at winter and spring with types of barley, oats, rape and faba beans. Selected leaves from young hardened beans were subjected to standardized freezing tests with different minimum temperatures ( T _min) and fluorescence was monitored. After a dark period basic fluorescence ( F _O was induced by 0.2 μmol m⁻² s⁻¹ pulsed red light and maximum fluorescence ( F _m) was assayed at different light intensities. 1500 μmol m⁻² s⁻¹ rendered to give the maximum possible output of Fm and best differentiation of differently damaged leaves by F _n= F _m - F _O. Leaf temperature during measurement and during a short storage (± 2 h) should be kept at about 0°C to avoid biases between differently damaged leaves. The measuring spot on the leaf must be standardized since fluorescence response differed at the tip and base of a leaflet, but not between the two leaflets of a faba bean leaf. The applicability of F _rr (ratio of F _r of stressed to unstressed leaves) as a measure of resistance was demonstrated by comparison of winter hardiness of cultivars with freezing resistance calculated from the relationship of F _vr and the T _min used in freezing tests.     

Effects of Soil Moisture on Gas Exchange, Partitioning of Fed 14CO2 and Stable Carbon Isotope Composition (δ13C) of Leymus chinensis Under Two Different Diurnal Temperature Variations

In a pot experiment under controlled condition, Leymus chinensis was grown at five soil water contents and two diurnal temperature variation levels. The leaf relative water content of L. chinensis decreased under soil drought conditions, and increased at high diurnal temperature variation (30/20 °C). Severe and very severe soil drought remarkably reduced photosynthetic rate, stomatal conductance, transpiration rate and water use efficiency (WUE), especially at the low temperature variation. Severe drought mainly increased the specific radioactivity of ¹⁴C of sheaths, roots and rhizomes, but significantly decreased that of fed leaves and the not fully expanded leaves. Root percentage of total radioactivity remaining in the whole plant increased from 15 % at 30/25 °C to 28 % at 30/20 °C. Leaf carbon stable isotope composition (δ¹³C) increased with soil drought, ranged from ?26 ‰ of the well‐watered to ?24 ‰ of severe drought treatments. High diurnal temperature variation improved leaf water status, and increased partitioning of carbon to root and δ¹³C values, especially under severe soil drought conditions. In conclusion, higher diurnal temperature variation enhanced the resistance of the plant to drought.     

The Effects of Temperature and Soil Moisture on Chickpea (Cicer arietinum L.) Genotype Sensitivity to Isoxaflutole

Isoxaflutole at 75 g ai ha^?1 is registered in Australia for the control of several broadleaf weeds in chickpea (Cicer arietinum L.). Although isoxaflutole provides satisfactory control of problematic weeds, under certain conditions crop injury can occur. Higher air temperature and moisture content of soil are reported to affect the metabolism of soil applied herbicide. Controlled environment experiments were used to determine the tolerance of chickpea to isoxaflutole under a range of temperature and soil moisture levels. For the soil moisture study, the variables examined were two desi chickpea genotypes (Kyabra as a tolerant cultivar and Yorker as a sensitive cultivar), three soil moisture levels [50 % field capacity (FC), 75 % FC and FC] with three herbicide rates [0, 75 (recommended rate) and 300 g ai ha^?1]. For the temperature by soil moisture study, the variables examined were two other desi chickpea genotypes (97039‐1275 as a tolerant line and 91025‐3021 as a sensitive line), three temperature regimes (20/5, 30/15 and 35/25 °C), two soil moisture conditions (50 % FC and FC) with the same three herbicide rates. The results demonstrated that the chickpea genotypes exhibited differential tolerance to isoxaflutole, but that differences in response were affected by rate, temperature and soil moisture. Increasing temperature and soil moisture content made the susceptible chickpea genotype more vulnerable to isoxaflutole damage. Injury to the susceptible genotype in terms of increased leaf chlorosis and reduction in shoot height and dry matter production increased as soil moisture increased from 50 % FC to FC and temperature increased from 20/5 to 35/25 °C. Overall damage of the sensitive genotype from increasing rates of isoxaflutole also increased when soil moisture content increased from 50 % FC to FC within the fixed temperature regime of 30/15 °C. The sensitivity of chickpea to isoxaflutole depends on existing temperature and moisture content and the chances of crop damage were enhanced with increasing temperature and moisture levels.     

不同土层测墒补灌对小麦旗叶光合特性和干物质积累与分配的影响

2011-2012和2012-2013年连续2个小麦生长季,在大田条件下,设置0~20 cm (D1)、0~40 cm (D2)、0~60 cm (D3)和0~140 cm (D4) 4个土层测定土壤含水量,以各土层平均土壤相对含水量拔节期65%和开花期70%为目标相对含水量,全生育期不灌溉为对照处理 (D0),研究依据不同土层的土壤含水量测墒补灌对小麦旗叶光合特性和干物质积累与分配的影响。结果表明：D2的开花期叶面积指数和单位土地面积上旗叶叶面积、开花后7 d和14 d的旗叶净光合速率和实际光化学效率均高于其他处理,而气孔限制值低于其他处理;D2的成熟期干物质积累量、开花后干物质向籽粒的分配量和开花后同化物分配对籽粒的贡献率亦高于其他处理。两年度D2的籽粒产量分别为9367.4 kg hm^-2和9727.5 kg hm^-2,均显著高于其他处理;同时,D2的水分利用效率高于D0、D3和D4处理,与D1处理无显著差异。因此,于小麦拔节期和开花期依据0~40 cm土层的土壤含水量测墒补灌是同步实现高产和高水分利用效率的有效措施。     

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.     

多效唑、烯效唑对油菜‘秦优1618’苗期特性和抗寒性的影响

为探索多效唑和烯效唑对油菜新品种‘秦优1618’抗寒性的影响,采用多效唑150 mg/L(C1)、300 mg/L(C2),烯效唑80 mg/L(C3)、160 mg/L(C4)喷施6~7叶期油菜幼苗1次,研究多效唑和烯效唑对幼苗生长调控、生理特性和抗寒性的影响。结果显示：采用多效唑150 mg/L(C1)或烯效唑80 mg/L(C3)处理6~7叶期幼苗,可有效降低苗期薹茎高、茎叶干质量、最大叶长度和宽度,对绿叶数影响不显著,有效提高根茎粗、根长、侧根数、根干质量和根冠比,形成壮苗;同时可增加叶片叶绿素和可溶性糖含量,降低相对电导率,提高叶片净光合速率,降低越冬死亡株率和冻害指数,提高抗寒性。     

Morph-physiological responses of cotton interspecific chromosome substitution lines to low temperature and drought stresses

Limited knowledge about genetic and physiological traits associated with drought and low temperature stresses and narrow genetic diversity in Upland cotton (Gossypium hirsutum L.) are serious impediments in its genetic improvement. The objectives of this research were to determine the genetic and physiological traits associated with drought and low temperature effects and to identify chromosomal effects on these traits using chromosome substitution (CS) lines from three alien species of Gossypium, G. barbadense, G. tomentosum, and G. mustelinum, respectively. Two experiments were conducted to study low temperature and drought stress effects during seedling emergence and early growth stages in 21 cotton CS-lines with parent, Texas Marker (TM)-1. In Experiment I, plants were grown at optimum (30/22 °C) and low (22/14 °C) temperature conditions under optimum water and nutrient conditions. In Experiment II, plants were grown at optimum water (soil moisture content of 0.167 m³ m^?3) and in drought (soil moisture content 0.105 m³ m^?3) conditions under optimum temperature conditions. Above- and below-ground growth traits including several root traits of the CS lines were assessed at 25 days after sowing. The findings suggest which substituted chromosome or chromosome segment from the alien species likely harbors one or more genes for higher and lower tolerance to low temperature, respectively. CS-T04 and CSB08sh showed higher and lower tolerance to low temperature, respectively and CS-T04 and CS-B22sh showed higher and lower tolerance, respectively, to drought. CS lines are valuable analytical tool and useful genetic resources for targeted exploitation of beneficial genes for drought and low temperature stresses in Upland cotton.     

Relationship Between Biomass Yield of Field Grown Maize Genotypes and Seedling Traits under Controlled Conditions

Investigations were done on six maize inbred lines of different origin and their diallel set of crosses. Seedlings grown at 14°, 22°, 30° and 38°C until three leaves stage were studied for morphological, anatomical and photosynthetic traits of leaves. These traits were screened for correlation with shoot dry weight at harvest under field conditions i) in 1981 and 1982 in North Germany, cool climate (CS); ii) 1981 in Thailand (WS). The correlation between seedling traits under controlled conditions and shoot dry weight under field conditions markedly changed after anthesis. Some few seedling traits closely correlated with biomass yield, favourably at 14° and 38°C. They mostly belonged to the morphology and anatomy of the leaves (area first leaf at 38°C, r = 0.6—0.7, all locations; depth of stomata below the epidermal surface at 38°C, r =—0.5 at CS and —0.7 at WS). In spite of significant correlations between single seedling traits and biomass yield a relyable prediction of biomass yield should best be based on a carefully chosen set of seedling traits.     

Leaf stomatal conductance and stomatal morphology of Musa germplasm

Drought tolerance combined with resistance to black sigatoka (BS) disease are two desirable traits for plantains in some parts of the tropics. Field evaluation of leaf stomatal conductance, single leaf transpiration rate, photochemical efficiency, and role of stomata in BS resistance, was done for 18 genotypes of Musa spp., which included diploid and triploid banana and plantains and tetraploid plantain hybrids, at a sub-humid and a humid site. Conductances were significantly (P ≤ 0.01) higher for leaf abaxial than adaxial surfaces (S), while clonal (C) differences were significant (P ≤ 0.05). Interactions between sampling period (T: morning vs afternoon) and location (L), and clone and location (C × L) were significant for both conductance and transpiration; (C × T × L) interaction was significant for conductance. Significant interactions for (C × L) and (C × T) suggested that conductance and transpiration of a specific clone need to be considered for a given environment. Total variation in conductance was explained by the following variables: S, C, (C × L), (C × T), and (C × L × T). In general, ABB cooking banana had higher conductances than other Musa taxonomic groups (AAB, AA, AAA, and AAAB). Evaluation of morphological and physiological traits of leaf stomata indicated that the resistance to BS disease is due to non-stomatal mechanisms. This revised version was published online in July 2006 with corrections to the Cover Date.     

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.     

A Quantitative Method to Assess Freezing Resistance in Faba Beans

In order to quantify freezing resistance (R₅₀) of winter faba beans from a limited number of plants, leaves were exposed to artificial freezing stresses with different test temperatures (TT_i). Injury (I_i) was assessed by rating (score: 0—8) and by conductivity measurements. The basic assumption that I_i depends almost linearly on TT_i over a sufficiently broad range with a constant ΔI/ΔTT could be verified and hence a formula is presented to compute freezing resistance R₅₀= (I_i—I₅₀) ×ΔTT/ΔI + TT_i with I₅₀ being a medium injury. This formula allows to quantify resistance by assessing I_i after freezing test(s) with definite TT_i. About 25 leaves are required. Rating appeared preferable to conductivity measurements because of easier and quicker performance and a slightly better discrimination between samples of different resistance. Based on a standardized freezing test, ΔI/ΔTT was determined. Application of the formula with ΔI/ΔTT = 2.5 units/°C for unhardened and hardened leaves, restrictions and experiences are discussed.     

Traits associated with dry edible bean (Phaseolus vulgaris L.) productivity under diverse soil moisture environments

Two experiments were conducted in the Rift Valley, Ethiopia (8°N and 39°E) to determine associations between eight plant traits and seed yield, and to obtain estimates of narrow sense heritability for the traits. Experiment I evaluated seven dry edible bean cultivars/lines at two locations to simulate different soil moisture stress, including, Debre Zeit(non-stress) and Dera (moderate-stress). Experiment II evaluated 25 cultivars/lines in three environments including, Melkassa early planted (non-stress), Melkassa late planted (high-stress), and Dera (moderate-stress). A randomized-complete-block design with three replicates was used in both experiments. Plant traits evaluated were seed yield, pods plant^-1, seeds pod^-1, 100 seed weight, root dry weight, hypocotyl diameter, plant biomass, plant height and days to flowering. Plant traits that were significantly associated with seed yield were included in a stepwise-regression model to determine which trait or combination of traits provided the best model to estimate seed yield in each environment. An analysis of variance was conducted to test main effects and interactions between plant traits and environments. Significant variation among lines occurred for seed yield and all plant traits in both experiments. Strong positive correlations were observed between plant biomass and seed yield in all environments. Seed yield and pods plant^-1 were also highly associated in four of the five environments. Stepwise regression models indicated that the combination of pods plant^-1 and plant biomass consistently contributed to seed yield prediction, while other traits did not. Because both plant biomass and pods plant^-1 had moderate to high narrow sense heritability estimates and low GE interactions, they should be useful as indirect selection criteria to improve and stabilize seed yield in a breeding program. This revised version was published online in July 2006 with corrections to the Cover Date.     

Variability and Correlations in Grain Sorghum Genotypes (Sorghum bicolor [L.] Moench) Under Drought Conditions at Different Stages of Growth

Twenty-two genotypes of grain sorghum were grown under drought conditions by omitting one irrigation during stages of before flowering period, kernel filling period, and physiological maturity period at Assiut Univ. Farm in 1987 and 1988 seasons. The results obtained revealed that considerable variation existed among genotypes for all the studied traits. The most effective moisture stress treatment in reducing grain yield, panicle weight and plant height was during flowering stage. While 1000-kernel weight was much affected by moisture stress during grain filling period. The genotype x year interaction (σ²_gy) was large compared to genotype x irrigation treatment (σ²_gl) indicated that genotypes responded differently when they were grown from year to year. The genotypic variance (σ²_g) for all traits were large reflecting the importance of genetic variability. Both phenotypic and genotypic correlations among traits showed that plant height and 1000-kernel weight were highly correlated with grain yield, while leaf area index was low associated with plant height.