The efficiency of visual assessment for yield and its components in winter oat rows

The efficiency of visual assessment of grain yield and yield components in 0–75 m rows of winter oats was, in general, moderately high. Only eight or less lines were needed to be saved in six out of eight cases to retain at least 50% of the best four lines from the set of 40 lines. Assessments of yield/row and tillers/row were more effective than assessments of grains/panicle and 1000-grain weight on the basis of the proportion of variation accounted for by regression of visual assessment on actual performance. An experienced oat breeder was more successful in his assessment than another assessor unfamiliar with the crop. Assessments of yield/row by the experienced assessor were apparently biased towards assessments of grains/row as the single most easily assessed character, while the assessor unfamiliar with the crop attempted to take tillers/row and 1000-grain weight into account in his assessments. Implications to a winter oat breeding programme are indicated.     

Visual assessment of grain yield and its components in single plants and ears of spring barley

Visual assessments of yield/plant and tillers/plant were more effective than unaided assessments of grains/ear and 1000-grain weight on a per plant basis. Assessments of the latter yield components were generally improved by the use of specially developed keys described by Ismail & Valentine (1983). Gains in efficiency were associated with the amount of extra time spent on making these assessments. Assessments of yield/ear were not more effective than assessments of yield/plant. This was attributed to the ease of assessment of tillers/plant which was strongly associated with yield/plant. Assessments of grains/ear and 1000-grain weight in single ears were clearly more effective than corresponding assessments in single plants in which there is high variability between ears. Apart from using keys, further improvements in the assessments of grains/ear and 1000-grain weight are necessary in order to increase the effectiveness of single plant selection in the F₂ generation which is the first opportunity of increasing yield in later generations.     

Estimation of genetic parameters in barley (Hordeum vulgare L.)

Summary Four exotic and four indigenous strains of barley were used for making diallel crosses. The sets of parents and crosses making full, half and quarter diallel were analysed in a randomized block design for plant height, number of effective tillers, ear length, grain yield per plant, 100 grain weight and number of grains per ear.The three alternatives of diallel were similar with respect to the estimates of degree of dominance, general combining ability and specific combining ability, indicating that all these three methods of diallel were equally efficient. However, as the number of entries are minimum in quarter diallel, it would be economical in terms of cost, time and labour to estimate genetic parameters by this method. Average degree of dominance was found in the range of overdominance. The ranking of parents on the basis of their array mean was similar to the ranking based on gca effects. Similarly, the ranking of crosses on the basis of per se performance was similar to the ranking based on sca effects. This suggests that the selection of best general combiner or best cross combinations may be easier and more effective through array mean for per se performance rather than through high gca and sea effects, respectively. From among 56 crosses, IB-226 X X C-164 was the one which showed superiority for maximum number of characters followed by AB-12/59 X PTS-57. High sea effect for plant height, ear length, grain yield, 100 grain weight and number of grains per ear was the result of cross between parents having high X low general combining ability, indicating additive X dominance type of gene interaction. For number of effective tillers, high sca was produced by low x low general combiners, indicating dominance x dominance gene interaction.Part of a Ph. D. thesis submitted by senior author to Haryana Agricultural University, Hissar.     

Variation in monoculture and in mixture for grain yield and other characters in spring barley

Fourteen north-west European spring barley cultivars were grown alone or in binary mixtures sampled according to a partial diallel scheme. On the basis of the association between cultivars in mixture and monoculture, three groups of characters were distinguished. Group A characters, plant height, ear weight/tiller, grain yield/tiller, number of grains/tiller and 1000-grain weight, showed strong positive associations between performance in monoculture and mixture. Group B characters, number of tillers/plant and harvest index showed incomplete positive associations, while for group C characters, dry matter/plant, ear weight/plant, grain yield/plant and number of grains/plant, associations were weak or non-existent. Compound characters in group C showed less genetic variation in monoculture and lower general competitive effects in mixture than component characters in groups A or B. These results clearly indicate that while selection for grain yield and other characters on a per plant basis (group C characters) is confounded by intergenotypic competition, characters such as the yield components number of grains/tiller and 1000-grain weight (group A characters) are hardly affected in this range of cultivars. Selection for opposing group A characters may start in the F₂ generation, while any selection for group B and C characters should be delayed until later generations. The merits of indirect selection for yield using visual assessment of yield components are discussed. Separate analyses obtained by the inclusion of spring wheat cv. Timmo in monoculture and in the set of mixtures indicated that the use of spring wheat plants to minimise intergenotypic competition ranges from superfluous (group A characters) to useless (group C characters). A large degree of mixture advantage and the lack of complementary dominance and suppression between competitor and associate was attributed to the relatively low density of plants in the experiment which, though suitable for single plant selection, is not typical of normal seed rates for cropping.     

High productivity of wheat intercropped with maize is associated with plant architectural responses

Mixed cultivation of crops often results in increased production per unit land area, but the underlying mechanisms are poorly understood. Plants in intercrops grow differently from plants in single crops; however, no study has shown the association between plant plastic responses and the yield advantage. Here, we assessed the productivity of wheat–maize intercropping as compared to sole wheat and sole maize, and the associated differences in wheat shoot and leaf traits. In two field experiments, intercrop wheat and maize were both grown in alternating strips consisting of six rows of wheat and two rows of maize. The traits of wheat plants in border rows of the strips were compared to the traits of plants in the inner rows as well as those in sole wheat. Leaf development, chlorophyll concentration and azimuth, as well as the final leaf and ear sizes, tiller dynamics of wheat and yield components of both crops were determined. The relative densities of wheat and maize in the intercrop were 0.33 and 0.67, respectively, but the corresponding relative yields compared to the respective monocultures were 0.46 for wheat and 0.77 for maize. Compared to wheat plants in the inner rows of the intercrop strips as well as in the monoculture, border‐row wheat plants in the intercrop strips had (a) more tillers owing to increased tiller production and survival, and thus more ears, (b) larger top leaves on the main stem and tillers, (c) higher chlorophyll concentration in leaves, (d) greater number of kernels per ear and (e) smaller thousand‐grain weight. Grain yield per metre row length of border‐row wheat was 141% higher than the sole wheat, and was 176% higher than the inner‐row wheat. The results demonstrate the importance of plasticity in architectural traits for yield advantage in multispecies cropping systems.     

The effect of tiller removal and tiller defoliation on competition between the main shoot and tillers of spring barley

In glasshouse and field experiments the source-sink relations of the main shoot of plants of spring barley were modified by tiller removal and tiller defoliation. Decreasing competition by tiller removal promoted the growth of the residual main shoot and its component parts, and the earlier tillers were removed the greater was the effect. Stem dry weight was increased four-fold in the glasshouse by early tiller removal and was doubled in the field experiment. The grain yield of the main shoot ear was increased by 26 – 30% by tiller removal compared with tillering control plants and this was due to larger grains in all spikelet positions. On the other hand increasing competition by regular tiller defoliation had relatively little effect on the growth and development of the main shoot in the glasshouse study, but in the field the main shoot grain yield was reduced by 10% compared with the control. The main effect of tiller defoliation was on the development of tillers. In the glasshouse tillers survived repeated defoliation, continued to be produced, and the majority produced grain but with fewer and smaller grains per ear than in control plants. Tiller growth was supported by the import of assimilate from the main shoot and this was accompanied by an increase in the photosynthetic rate of the main shoot leaves. In the field all defoliated tillers died within 4 wk. These responses are discussed in terms of the physiological interrelations between the main shoot and tillers.     

恢复措施对退化草地羊草种群有性生殖数量特征的影响

在封育和翻耙处理的退化羊草草地上,对羊草种群有性生殖的数量特征进行了比较研究．结果表明,翻耙样地羊草种群密度下降显著,生殖蘖密度变化不显著,生殖蘖穗长、节间长、生殖生长比率、穗节数、小穗数、小花数、饱满籽实数和结实率都有显著增长,籽实产量、净籽实重和千粒重分别是封育样地的2．68、3．49和1．3倍．在翻耙样地中,羊草种群发育有复小穗的生殖蘖比封育样地多16％,生殖蘖上复小穗的数量也显著增加,生殖蘖以相对少的小穗,生产了较多的小花和更多的籽实来提高种群的籽实产量．两个样地中羊草种群的生物量生殖分配在种群对生殖蘖RA1、生殖蘖对穗序RA4、穗序对籽实RA6 3个层次上无显著差异,而种群对穗序RA2、生殖蘖对籽实RA5的生殖分配差异显著,种群对籽实RA3的生殖分配差异极显著．     

Observations on the effects of mildew, Erysiphe graminis, on growth of spring and winter barley

In field plots, early and severe attacks of powdery mildew on spring barley plants greatly reduced the vigour, decreased the amount of root, the number of ear-bearing tillers and the grain size. In less severe, or later attacks, mildew mainly affected the grain size. On winter barley, where mildew attacked both in autumn and in spring, yield was decreased more than when only a spring attack occurred. The early attack retarded development of the root system, increased winter kill and decreased the number of ears reaching maturity. Because early mildew attack affects yield, it is not always possible to correlate yield loss with intensity of mildew at any one growth stage of the crop.     

Assimilation of 14CO2, Assimilate Translocation and Grain Yield in Three Primitive Nepalese Varieties and a European Cultivar (Senta) of Six-row Barley (Hordeum vulgare L.)

Three primitive varieties of six-row barley from Nepal withdifferent degrees of awn development were compared with a bredEuropean cultivar, Senta, under glasshouse conditions, fromanthesis onwards. Apart from the flag leaf the last three mainshoot leaves of the Nepalese varieties were smaller than thoseof Senta, and the lower leaves did not become senescent duringthe first 3 weeks of grain filling. In all varieties the penultimateleaf was the major assimilatory organ but in Senta the relativecontribution of the awns increased with time as the leaves senescedand fixed almost half of the total ¹⁴C assimilated by the shoot.Whereas the supply of assimilate to the ear increased with timein Senta, the reverse was found for the Nepalese varieties andoverall a smaller proportion of assimilate was supplied to theear in these varieties. The grain yield of the main shoot earof the two Nepalese varieties studied in detail was one-thirdof that of Senta; there were only approximately half the numberof grains in each median and lateral row of the ear and thegrains were smaller. There was no correlation between the degreeof awn development or the pattern of awn arrangement withinthe ear and the size of individual grains. The total biomassof the Nepalese varieties was much lower than that of Sentabut there were no differences in the harvest index or in tillerproduction. However, the Nepalese varieties, in contrast toSenta, had a mean grain yield per tiller comparable to thatof their main shoot and thus it appears that selection by plantbreeding may have increased the dominance of the main shoot. Hordeum vulgare L., barley, primitive barley varieties, carbon dioxide assimilation, assimilate translocation, grain filling     

Influence of the Russian wheat aphid <Emphasis Type="Italic">Diuraphis noxia</Emphasis> (Kurdjumov) (Homoptera,Aphididae) on productive qualities of spring bread wheat and barley grown from the seeds from aphid-infested spikes

The aftereffects of the Russian wheat aphid (RWA) Diuraphis noxia on sowing and productive qualities of barley and spring bread wheat grain were assessed. Seeds of 4 cultivars of barley (Volgar, Povolzhsky 65, Kazak, and Povolzhsky 16) and 4 cultivars of spring wheat (Kinelskaya 59, Kinelskaya Otrada, Kinelskaya Niva, and Kinelskaya 2010) from spikes infested and uninfested with RWA in 2007 and in 2014 were sown in the subsequent years, using 0.5 m² experimental plots in four replications, at a seeding rate of 300 grains/m². The least significant difference (LSD_0.5) was used to compare the mean ± standard deviation (SD) values. The field germination rate of seeds from spring wheat spikes damaged by RWA was reduced by 15%. Of the components of grain yield, barley and spring wheat grown from seeds from the infested spikes showed a 23-31% smaller number of productive tillers before harvesting, a 16% smaller number of grains per spike, a 13-16% lower grain weight per spike, and a total yield loss of 33-42%. In hulless bread wheat RWA fed on the developing kernels inflicting greater damage, whereas the hulled barley seeds were practically not damaged. The mean yield loss of the barley and spring wheat spikes infested with RWA was 24-32% and 50-66%, respectively. Due to the greater tillering capacity and formation of secondary productive tillers in barley, about 52% of the productive barley tillers and 37-39% of spring wheat ones were infested with RWA, which resulted in a comparable yield loss (20-25% in barley and 19-23% in spring wheat). Resistance to RWA was higher in spring wheat and barley cultivars with a shorter vegetation period, looser spikes, and thinner culm walls. The length of productive tillers damaged by RWA was reduced by 21-28%, which determined a lower incidence of leaf diseases.     

The Effect of Intraspecific Competition on the Phenotypic Plasticity of Morphological and Agronomic Characters of Four Maize Hybrids

The plasticities of 16 characters were studied in four maize(Zea mays, L.) hybrids grown at seven equidistant spacings andat four growth stages in 1 year. Plasticity was a measure ofthe extent to which the expression of a character was modifiedby changes in plant density. The hybrids differed in their plasticitiesfor all characters studied. Furthermore, the characters of ahybrid showed different plasticities. The most plastic characterswere grain yield per plant and yield per unit area, and theleast plastic were ear row number and ear height. The hierarchyof plasticities was essentially identical in all hybrids. Thedouble-cross hybrids showed non-significantly higher mean plasticitiesthan the less heterogeneous genotypes M.C. 101 and Warwick SL209.     

Mapping QTL controlling yield and yield components in a spring barley (Hordeum vulgare L.) cross using marker regression

An RFLP map constructed from 99 doubled haploid lines of a cross between two spring barley varieties (Blenheim × Kym) was used to localize quantitative trait loci (QTL) controlling grain yield and yield components by marker regression and single-marker analysis. Trials were conducted over three years. Genotype-by-year interaction was detected for plant grain weight and ear grain weight so they were analysed separately for each year. None was detected for thousand-grain weight and ear grain number so data were pooled over years. A total of eleven QTL were detected for plant grain weight over two years and fourteen for ear grain weight over three years. Seven QTL were detected for plot yield. The locus with the largest effect was on chromosome 2(2H)L and accounted for 19% of the variation in the progeny. Eight QTL were detected for thousand-grain weight and five for ear grain number. Many of the QTL detected were in comparable positions in each year. Yield and yield components were only partly correlated. Comparisons based on common RFLP markers showed that some QTL were found in positions similar to those identified in other studies. For a number of QTL the identification of linked markers provided suitable opportunities for marker-assisted selection and improvement of barley and reference markers with which to analyse the homoeologous chromosome regions of wheat and other cereals.     

Some effects of barley yellow dwarf virus on spring and winter cereals in field trials

The tolerance of spring and winter cultivars of wheat, barley and oats to infection by barley yellow dwarf virus (BYDV) was examined in field tests. Sererely affected plants were stunted and grain yields were considerably reduced. These changes in infected spring barley cultivars were associated with decreases in both ear length and number and sizes of grain. Most barley and oat cultivars were more susceptible than wheat cultivars. Yield losses decreased with successively later dates of inocultaiton, the yield response being characteristic of the tolerance of individual cultivars. Differences between tolerant and susceptible cultivars were insignificant in most cases where infection occurred after growth stage 7. Individual seedling symptoms assessed in April and May were more closely related to each other and to yield losses than those recorded in March and June. The incorporation of seedling symptoms into indices of infection permits estimates of decrease in yield to be made by applying the formulae, DY = (LC+LA+SH)/3 to barley cultivars and DY = 1.7 × (LC+LA+SH)/3 - 7 to oat cultivars. Thus decreases in grain yield (DY) can be related to decreases in seedling height (SH) and increases in percentage of leaf area discoloured (LA) and intensity of discoloration (LC). Plot symptoms of infection, scored on a 0–7 scale, offered a more convenient method of assessment than individual seedling symptoms. Plot scores (PA) were closely correlated with other seedling symptoms and with decreases in grain yield (DY), and can thus be used to estimate yield losses by substituting into the formula, DY = 14PA (April)-8. This formula was found to be applicable to all cereal cultivars examined in N.I.A.B. trials, there being no distinction between wheat, barley and oats.     

An investigation into the relations between some growth parameters and yield of barley

Twenty-five field experiments on barley were done at four sites from 1970 to 1975, with an additional site in 1975, comparing five rates of nitrogen application. The crops were sampled at c. 14-day intervals from about the four-leaf stage to maturity to follow changes with time in the dry weights of the constituent plant parts and to measure fertile tiller number, grain number per ear and grain weight. Some data have been selected from this body of information and regression analysis has been used to assess the possible importance of pre- and post-anthesis growth in determining the yield of barley. Ear emergence was taken as an approximate indicator of anthesis. Yield was closely related (r=+0–96) and almost equal to the amount of dry matter accumulated before ear emergence for twenty-one of the experiments, with a regression coefficient of 0–95. In two of the remaining experiments the regression coefficient was greater, 1–14; and smaller in the other two, o-8i. Plant population is also shown to affect the regression coefficient. Despite these anomalies grain yield was more closely related to plant dry weight at ear emergence than to the increase in weight after ear emergence (r =+0–79). The increase in plant dry weight after ear emergence was frequently less than the yield of grain, suggesting that the plant can compensate for inadequate photosynthesis during grain filling. The result of this compensation is a reduction in straw dry weight. This implies that previously assimilated dry matter is transported to the grain, or that respiratory losses from the straw are not replaced by current photosynthesis. These observations suggest that yield may be limited by sink capacity rather than by photosynthesis after ear emergence. The main component of sink capacity, grain number per m² was closely related to yield (r =+0–95) and is known to be determined at or before anthesis. Grain size was shown to be related to grain number per ear (r= 4- 0–99), suggesting that grain size is also, at least partially, determined at ear emergence. Therefore, all the yield components are determined, wholly or partly before ear emergence.     

Effects of fungicide treatments and variety on development, grain growth and yield of spring barley

The effects of four fungicide treatments for the control of mildew on spring barley were assessed in three field experiments, one in each of the years 1981, 1982, 1983. The fungicide treatments (+/ - triadimenol seed treatment and +/ - triadimefon foliar spray applied during early booting) were chosen to control mildew, and hence affect yield determining processes, at different times in the life of the crop. Two of the experiments also tested different nitrogen amounts and the third tested four varieties differing in their degree of mildew resistance. Mildew appeared too late to affect the production and survival of spikelets and shoots, but reduced average grain weight by reducing the rate of grain growth. Grains in the upper part of the ear had a considerably lower growth rate and final weight than grains in central and basal positions but there was no evidence that the effects of mildew on grain size depended upon grain position within the ear. Mildew incidence increased with increasing nitrogen and varietal susceptibility but there were few significant interactions between these factors and fungicide treatment for grain yield. The degree of mildew control achieved by the seed treatment varied with barley variety. Use of the two successive fungicide treatments did not yield more barley than use of either alone. Amongst varieties, grain positions within the ear and fungicide treatments there was a close correlation between rate of grain growth and final grain weight. Duration of grain growth was not related to rate of grain growth or final grain weight but was inversely correlated with mean temperature during the period of rapid grain growth. The temperature sums during the period of rapid grain growth were similar for the three years and it is suggested that a more precise knowledge of the relationships between mildew incidence, varietal susceptibility and rate of grain growth may enable more accurate predictions to be made about likely yield responses to fungicide treatments.     

Cross prediction studies on spring barley

Summary Additive genetic, dominance genetic and environmental correlations between pairs of agronomically important characters in five spring barley crosses were calculated from estimates of the components of variance and covariance, obtained by Triple Test Cross analysis. Phenotypic correlations were calculated from the Triple Test Cross family means and compared to the additive genetic correlations. Phenotypic correlations were generally lower than the additive genetic correlations and, occasionally, of different sign. The highest phenotypic correlations between single plant yield and its components were found with number of tillers whereas these were the lowest additive genetic correlations, thousand grain weight giving the highest. High dominance genetic correlations were found between single plant yield and both grain number and thousand grain weight thus indirect early generation selection for single plant yield using these two characters would be ineffective. Additive and dominance genetic correlations confirm association of the erectoides dwarfing gene with low thousand grain weight and plant yield.     

玉米空间诱变后代SP4选系配合力效应分析

利用返回式卫星“实践八号”搭载3份玉米自交系08-641、RP125和18-599, 从SP4代中选出多个诱变系按不完全双列杂交设计配制杂交组合, 在四川和云南两个环境条件下进行种植鉴定。配合力分析结果表明, 3份玉米自交系经空间诱变后各性状的配合力发生不同程度的变化, 同组诱变系材料在四川和云南两种环境条件下的配合力表现存在较大差异, 且表现配合力差异的性状不同。诱变系C03的穗长、穗行数、行粒数和单株产量4个性状一般配合力(General combining ability, GCA)在该组试验中的正向效应值均表现为最大, 且显著高于基础材料08-641, 可能具有较大育种潜势; 诱变系C01和C04部分产量构成性状的GCA显著高于对照, 但单株产量GCA表现不明显, 需在育种中加以改良利用; 诱变系C06、R18和S22所配杂交组合在产量及产量构成性状上的特殊配合力(Specific combining ability, SCA)表现较优, 这些结果为玉米杂交种的选育提供了重要参考。     

Effect of monoethanolamine on growth and biomass formation of rye and barley

Monoethanolamine (EA) applied to rye and barley as a foliar spray increased the biomass and grain yield formation of tillers (up to 14%) and promoted the growth of the basal stem parts (up to 17%). The increased production of tillers and the stimulated growth of basal internodes were associated with a higher nitrogen level in these plant parts. A sufficient nitrogen supply was an essential requirement for increasing the yield of tillers by EA.     

Effects of Shading the First Leaf on Growth of Barley Plants: I. Long-term Experiments

Plants of barley were grown under controlled conditions andthe first or second leaves covered with tubular shades thusreducing the light intensity at the leaf surface to low levels.Expansion of the shaded leaves was not prevented, but appearanceof the next leaf but one and all subsequent leaves on the mainstemwas delayed by up to 3 days. Primordia of the first four leaveswere present in the dry grain. Shade treatment delayed slightlythe initiation of the eighth and subsequent leaves and transitionto the double ridge stage at the mainstem apex. Shading the first leaf caused a temporary reduction in the rateof dry-matter increase of plants, but after 14 days the ratewas similar to that of control plants. Smaller effects werefound when the second leaf was shaded. Dry-matter productionfollowed two logarithmic phases in the period prior to awn emergence,and rates for the whole plant and for plant parts were similarfor control and shaded plants. Thus, apart from the initialperturbation, shading had no effect on growth in terms of rateof dry-weight gain. Shade treatment did not affect weight per grain or numbers ofgrain per ear, but over-all yield of grain was significantlyreduced since shading delayed the appearance of tillers andalso reduced the number of tillers bearing grain. The effectof shade was especially marked on tillers originating on primarytillers. Similar qualitative effects on tiller development werefound in an experiment on wheat.     

Hybrid performance and genetic distance as revealed by the (GATA)4 microsatellite and RAPD markers in pearl millet

 Genetic diversity in five cytoplasmic male-sterile and seven restorer lines of pearl millet was determined by DNA fingerprinting using a (GATA)₄ microsatellite and randomly amplified polymorphic DNAs (RAPDs). A total of 160 polymorphic loci were generated and, based on the polymorphism data, similarity index values ranged from 0.81 to 0.50. Cluster analysis was performed and relationships among these lines revealed that they were not in agreement with the available pedigree data. The per se performance of parents and hybrids was analyzed for days-to-50% flowering, plant height, productive tillers, ear length, ear width, 1000-grain weight and grain yield per plot. Path co-efficient analysis revealed that productive tillers, ear width and days-to-50% flowering had a relatively large positive effect. The correlation values were mostly not significant with respect to genetic distance, except for days-to-50% flowering, ear length and ear width. Our results have indicated that genetic-distance measures based on the (GATA)₄ microsatellite and RAPDs may be useful for the grouping of parents, but not for predicting heterotic combinations, in pearl millet. Received: 3 January 1998 / Accepted: 25 February 1998