Search

Societal Impact Statement Micronutrients such as zinc and iron are critical for human health. For the world's population that relies on cereal products to obtain micronutrients, the bioavailability (absorption of nutrients in the gut) can be hindered by an anti‐nutritional compound, phytate. Phytate accumulation in grain is affected by soil properties including phosphorus availability and arbuscular mycorrhizal (AM) fungi. Here, we investigated the effects of AM fungi and soil phosphorus fertilization on micronutrient bioavailability in durum wheat and found that fertilization greatly decreased the bioavailability of micronutrients, but AM fungi can take up more micronutrients, which can lead to improved bioavailability when the soil is not fertilized. Summary The bioavailability of micronutrients (zinc [Zn] and iron [Fe]) in cereal crops such as durum wheat is critically important for human nutrition. Bioavailability is a product of complex interactions between plant phosphorus (P) uptake and storage in grain (as phytate), and plant micronutrient uptake. The bioavailability of Zn and Fe in cereal grain is affected by soil nutrient concentrations and associations with arbuscular mycorrhizal (AM) fungi, but has been scarcely studied. A geographically diverse collection of 101 durum wheat genotypes was surveyed for grain bioavailability of Zn and Fe. Ten genotypes were then selected and grown with and without AM fungal inoculation and soil P fertilization to understand the effects of manipulating soil P availability and uptake on micronutrient bioavailability. The strongest negative effect on grain micronutrient bioavailability was soil P fertilization, however, it also led to increased grain weight. Crop variety selection had the greatest variation in the P‐fertilized soil, but AM fungal inoculation had a positive effect on bioavailability in one variety in the non‐fertilized soil. In order to grow more nutritious durum wheat crops, variety selection and AM fungal inoculation are important considerations. In general, there is a trade‐off between grain weight (yield) and micronutrient bioavailability in grain that could be addressed through breeding P‐deficiency tolerant varieties.

AP2/ERF is a plant‐specific transcription factor superfamily regulating plant growth, development and responses to multiple stresses. However, the roles of ERF genes in the growth and development of wheat (Triticum aestivum L.) remain elusive. In this study, a novel ERF gene TaERF73 was cloned from wheat. qRT‐PCR analysis showed that TaERF73 is predominantly expressed in roots. It responds to treatments of auxin, MeJA, ABA, low temperature and drought stresses. Ectopic expression of TaERF73 in rice caused short root length, indicating that TaERF73 is a negative regulator of root growth. Four SNPs were detected in TaERF73‐4B coding region through sequence polymorphism analysis. A dCAPS (derived cleaved amplified polymorphic sequence) molecular marker was developed based on the SNP at 119 bp (G/C) of TaERF73‐4B. Association analysis between genotypes and agronomic traits revealed that Hap‐4B‐2 is a haplotype of TaERF73‐4B associated with shorter plant height, higher thousand‐grain weight and longer root depth. The distributions of haplotypes in ten Chinese major wheat zones suggested that Hap‐4B‐2 has been positively selected in the breeding process. Together, the ERF gene TaERF73 is associated with root depth, plant height and thousand‐grain weight under drought, heat and well‐watered conditions. The molecular marker developed in this study could be a valuable source for marker‐assisted selection and genetic improvement in wheat.

Summary Argonaute (AGO) proteins and small RNAs (sRNAs) are core components of the RNA‐induced silencing complex (RISC). It has been reported that miRNAs regulate plant height and grain size in rice, but which AGO is involved in grain size regulation remains unclear. Here, we report that enhanced expression of OsAGO17, a putative AGO protein, could improve grain size and weight and promote stem development in rice. Cytological evidence showed that these effects are mainly caused by alteration of cell elongation. Expression analyses showed that OsAGO17 was highly expressed in young panicles and nodes, which was consistent with the expression pattern of OsmiR397b. SRNA sequencing, stem‐loop RT‐PCR and sRNA blotting showed that the expression of OsmiR397b was reduced in ago17 and enhanced in the OsAGO17 OE lines. Four OsmiR397b target laccase (LAC) genes showed complementary expression patterns with OsAGO17 and OsmiR397b. Combined with the results of immunoprecipitation (IP) analysis, we suggested that OsAGO17 formed an RISC with OsmiR397b and affected rice development by suppression of LAC expression. In conclusion, OsAGO17 might be a critical protein in the sRNA pathway and positively regulates grain size and weight in rice.

Summary Starch is the most important form of energy storage in cereal crops. Many key enzymes involved in starch biosynthesis have been identified. However, the molecular mechanisms underlying the regulation of starch biosynthesis are largely unknown. In this study, we isolated a novel floury endosperm rice (Oryza sativa) mutant flo16 with defective starch grain (SG) formation. The amylose content and amylopectin structure were both altered in the flo16 mutant. Map‐based cloning and complementation tests demonstrated that FLO16 encodes a NAD‐dependent cytosolic malate dehydrogenase (CMDH). The ATP contents were decreased in the mutant, resulting in significant reductions in the activity of starch synthesis‐related enzymes. Our results indicated that FLO16 plays a critical role in redox homeostasis that is important for compound SG formation and subsequent starch biosynthesis in rice endosperm. Overexpression of FLO16 significantly improved grain weight, suggesting a possible application of FLO16 in rice breeding. These findings provide a novel insight into the regulation of starch synthesis and seed development in rice.

High night‐temperature (HNT) stress during the reproductive stage of rice (Oryza sativa L.) reduces spikelet fertility and yield by inhibiting important physiological processes. However, specifics such as the period of time that is most sensitive to HNT, is unknown. To investigate this, we conducted four controlled‐environment experiments with two rice cultivars, N22 (HNT tolerant) and WAB56–104 (HNT susceptible). These cultivars were exposed to varying durations and intensities of night temperatures (control, 24°C; HNT, 30 and 35°C) during the reproductive stage. The effect of HNT on spikelet fertility and grain weight varied with duration: spikelet fertility reduced by 47–77% when exposed to HNT for 15 nights, 6–29% when exposed for four nights, and 9–15% when exposed for 5.5 h (pre‐midnight, 1830–0000 h or post‐midnight, 0000–0530 h) for four nights. Spikelet fertility and grain weight were most sensitive to HNT during the first 4 d of anthesis, compared with 1–4, 5–8, and 9–12 d before anthesis. At anthesis, reduction in spikelet fertility did not differ significantly between pre‐ and post‐midnight high‐temperature treatments. Our results suggest that greatest sensitivity to HNT during the reproductive stage occurs during the first 4 d of anthesis, providing a reference for future studies involving HNT tolerance in rice.

Summary Marker‐based prediction holds great promise for improving current plant and animal breeding efficiencies. However, the predictabilities of complex traits are always severely affected by negative factors, including distant relatedness, environmental discrepancies, unknown population structures, and indeterminate numbers of predictive variables. In this study, we utilised two independent F1 hybrid populations in the years 2012 and 2015 to predict rice thousand grain weight (TGW) using parental untargeted metabolite profiles with a partial least squares regression method. A stable predictive model for TGW was built based on hybrids from the population in 2012 (r = 0.75) but failed to properly predict TGW for hybrids from the population in 2015 (r = 0.27). After integrating hybrids from both populations into the training set, the TGW of hybrids could be predicted but was largely dependent on population structures. Then, core hybrids from each population were determined by principal component analysis and the TGW of hybrids in both environments were successfully predicted (r > 0.60). Moreover, adjusting the population structures and numbers of predictive analytes increased TGW predictability for hybrids in 2015 (r = 0.72). Our study demonstrates that the TGW of F1 hybrids across environments can be accurately predicted based on parental untargeted metabolite profiles with a core hybridisation strategy in rice. Metabolic biomarkers identified from early developmental stage tissues, which are grown under experimental conditions, may represent a workable approach towards the robust prediction of major agronomic traits for climate‐adaptive varieties.

Physiological causes for grain weight determination in maize (Zea mays L.) are not clear. Source–sink relationships during grain filling modulate grain weight, and there are controversies regarding the degree of source limitation that may exist during grain filling. We aimed to analyze likely causes of the esponsiveness of maize grain weight to defoliation and degraining treatments imposed 15 d after silking, quantifying the responsiveness of grain weight to these source–sink manipulations in a large number of field conditions (52 background conditions in which source–sink manipulations were imposed). Grain weight was largely unresponsive to increases in source availability but was diminished by defoliations in six out of seven experiments. Interestingly, grain weight reductions due to defoliation were not hierarchical (grains from different positions along the ear responded similarly) and were not worsened by imposing a simultaneous heat stress. Heat affected the grain growth capacity directly, and indirect effects (through reducing source strength due to accelerated senescence) were not evident. The penalty imposed by heat was neither increased by defoliation nor diminished by degraining, and the reduction in grain weight was similar for grains with different potential size. Our study reinforced the concept that maize yield is limited by the sink strength during grain filling, even when grain weight may respond to reductions in the grain filling source–sink ratio. We gratefully acknowledge technicians of the Crop Physiology Laboratory for help in the management of the experiments, particularly with the tedious degraining required at relatively large scale in field plots. We thank Lucas Borrás (University of Rosario, Argentina) and Sotirios Archontoulis (Iowa State University, IA) for their comments and suggestions in earlier versions of this paper, as well as María Otegui (Associate Editor of Crop Science) for valuable suggestions made directly on the PDF file of the original submission. Funding was provided by Project 8031 of the Regional Fund for Agricultural Technology (FONTAGRO). R.A. Ordóñez held a University of Lleida predoctoral scholarship.

GW2 is emerging as a key genetic determinant of grain weight in cereal crops; it has three homoeologs (TaGW2-A1, -B1 and -D1) in hexaploid common wheat (Triticum aestivum L.). Here, by analyzing the gene editing mutants that lack one (B1 or D1), two (B1 and D1) or all three (A1, B1 and D1) homoeologs of TaGW2, several insights are gained into the functions of TaGW2-B1 and -D1 in common wheat grain traits. First, both TaGW2-B1 and -D1 affect thousand-grain weight (TGW) by influencing grain width and length, but the effect conferred by TaGW2-B1 is stronger than that of TaGW2-D1. Second, there exists functional interaction between TaGW2 homoeologs because the TGW increase shown by a double mutant (lacking B1 and D1) was substantially larger than that of their single mutants. Third, both TaGW2-B1 and -D1 modulate cell number and length in the outer pericarp of developing grains, with TaGW2-B1 being more potent. Finally, TaGW2 homoeologs also affect grain protein content as this parameter was generally increased in the mutants, especially in the lines lacking two or three homoeologs. Consistent with this finding, two wheat end-use quality-related parameters, flour protein content and gluten strength, were considerably elevated in the mutants. Collectively, our data shed light on functional difference between and additive interaction of TaGW2 homoeologs in the genetic control of grain weight and protein content traits in common wheat, which may accelerate further research on this important gene and its application in wheat improvement.

Water deficiency affects grain proteome dynamics and storage protein compositions, resulting in changes in gluten viscoelasticity. In this study, the effects of field water deficit on wheat breadmaking quality and grain storage proteins were investigated.; Results: Water deficiency produced a shorter grain-filling period, a decrease in grain number, grain weight and grain yield, a reduced starch granule size and increased protein content and glutenin macropolymer contents, resulting in superior dough properties and breadmaking quality. Reverse phase ultra-performance liquid chromatography analysis showed that the total gliadin and glutenin content and the accumulation of individual components were significantly increased by water deficiency. Two-dimensional gel electrophoresis detected 144 individual storage protein spots with significant accumulation changes in developing grains under water deficit. Comparative proteomic analysis revealed that water deficiency resulted in significant upregulation of 12 gliadins, 12 high-molecular-weight glutenin subunits and 46 low-molecular-weight glutenin subunits. Quantitative real-time polymerase chain reaction analysis revealed that the expression of storage protein biosynthesis-related transcription factors Dof and Spa was upregulated by water deficiency.; Conclusion: The present results illustrated that water deficiency leads to increased accumulation of storage protein components and upregulated expression of Dof and Spa, resulting in an improvement in glutenin strength and breadmaking quality. © 2018 Society of Chemical Industry.; © 2018 Society of Chemical Industry.

Flowering time is the most critical developmental stage in wheat, as it determines environmental conditions during grain filling. Thirty‐five spring durum genotypes carrying all known allele variants at P p d ‐1 loci were evaluated in fully irrigated field experiments for three years at latitudes of 41°N (Spain), 27°N (northern Mexico) and 19°N (southern Mexico). Relationships between weight of central grains of main spikes (W) and thermal time from flowering to maturity were described by a logis‐tic equation. Differences in flowering time between the allele combination causing the earliest (GS100/Ppd‐B1a) and the latest (Ppd‐A1b/Ppd‐B1a) flowering were 7, 20 and 18 days in Spain, northern Mexico and southern Mexico, respectively. Flowering delay drastically reduced the mean grain filling rate (R) and W at all sites. At autumn‐sowing sites, an increase of 1°C in mean temperature during the first half of the grain filling period decreased W by 5.2 mg per grain. At these sites, W was strongly dependent on R. At the spring‐sowing site (southern Mexico), W depended on both Rand grain filling duration. Our results suggest that incorporating the allele combina‐tions GS100/Ppd‐B1a and GS105/Ppd‐B1a (alleles conferring photoperiod insensitiv‐ity) in newly released varieties can reduce the negative effects of climate change on grain filling at the studied latitudes info:eu-repo/semantics/publishedVersion

MicroRNAs (miRNAs) are small noncoding RNAs which regulate various functions related to growth, development, and stress responses in plants and animals. Rice, Oryza sativa, is one of the most important food crops of the world. In rice, a number of quantitative trait loci (QTL) controlling yield-related traits have been identified. Some of them are actually controlled by miRNAs, which control various yield-related quantitative traits in rice. On one hand, many of these miRNAs are found to regulate more than one yield-related traits, such as tillering, grain size, and branch number of a panicle. On the other hand, a rice yield-related trait is usually controlled by multiple miRNAs, for example, grain size being controlled by miR156, miR167, miR396, miR397, and miR1432. In rare case, a single miRNA may specifically regulate only one yield-related trait, such as, miR444 regulating rice tillering. In this review, we focus on the functions of miRNAs in controlling yield-related quantitative traits in rice, including panicle grain number, grain weight/size, panicle length and branching, tiller number per plant, spikelet number, seed setting rate, and leaf inclination, and discuss how to modulate the expression of these miRNAs using modern molecular biology tools to promote grain yield. This article is categorized under: RNA in Disease and Development > RNA in Development.

The effects of heat stress (mean day/night temperatures were 29/18 and 35/18°C for control and heat stress treatments, respectively) at 1–10 or 11–20 days after pollination (DAP) on grain yield and quality of two waxy maize varieties, Suyunuo5 and Yunuo7, were studied. The decrease in grain number and fresh grain yield was more severe when heat stress was introduced early. The responses of grain weight and its components to heat stress were dependent on the variety and heat stress stage. Heat stress increased the starch granule size and volume percentage of diameter larger than 17 μm in both varieties. Crystallinity, iodine binding capacity, and pasting and gelatinization temperatures were increased in both varieties under heat stress at 11–20 DAP; however, the response to early-stage heat stress was variety dependent. Peak viscosity and retrogradation percentage were increased by heat stress at either stage. These results suggest that heat stress decreases fresh grain yield and accelerates grain filling ...

Waterlogging, if occurring within the stem elongation period (SE), is particularly critical for yield determination. We quantified for the first time the effect of waterlogging duration during SE on yield and studied whether the effects were only direct on resource capture or whether there were feed-forward effects as well. We grew wheat (cv. Soissons) outdoors in long tubes (1.25 m deep) forming a normal canopy and imposed different treatments in SE to finish simultaneously around anthesis (0, 4, 8, 12, 16, 20 and 24 days) plus two complementary treatments (8 and 16 days) starting 10 days after the onset of SE. Yield was reduced linearly with the duration of waterlogging c. 2 % dwaterlogging−1. Treatments mainly affected pre-anthesis spike growth reducing the number of fertile florets and grains, not affecting fruiting efficiency. The magnitude of grain number loss was inversely proportional to the hierarchy of the spikes and spikelets. Grain weight was more marginally reduced, likely through the effects on the size of the ovaries of the developing florets. This reveals a direct effect of waterlogging on the capture of resources with no major feed-forward effects. Losses were in agreement with those from other studies for particular durations of waterlogging.

Although lipids and fatty acids (FA) represent only 1-3% of the grain weight, they can play an important role in regulating, modulating, and determining several chemical and physical properties of the grain and corresponding malts. The aim of this study was to evaluate the relationships between the content of FA in grain, malt, and wort with malt quality characteristics such as hot water extract (HWE) and apparent attenuation limit (AAL) in different commercial malting barley varieties. High and positive correlations were found between myristic acid and HWE (r = 0.71) and between stearic acid and AAL (r = 0.76), with intermediate correlations between palmitic, oleic, linoleic, and linolenic acids and AAL (r = >0.50) in grain. High and negative correlations were found between stearic acid and HWE (r = -0.66), and high and negative correlations were found between palmitic (r = -0.74) and linoleic (r = -0.60) acids and AAL in the wort. Results from this study showed that lipids, as well as the combination of unsaturated and saturated FA, might play a role in determining differences in HWE and AAL between the barley varieties analyzed. No clear evidence on HWE was observed when grain and malt samples from the same variety were compared. These results indicated that lipids and FA should be considered together with starch properties to explain differences between HWE and AAL.

Heat and drought are the most important wheat production constraints worldwide. The objectives of this research were to evaluate the independent and combined effects of drought and heat in SeriM82/Babax population. Genotypes showed 11, 38 and 52% losses in grain yield (YLD) in 2010–11 and 18, 25 and 48% in 2011–12 under heat, drought and combined stress, respectively. Seri M82 had higher YLD than Babax under heat and combined stress. Grain per spike and canopy temperature at vegetative stage (CTv) in irrigated, day to heading and CT at grain-filling stage (CTg) in drought, CTg and thousand-grain weight (TGW) in heat and in combined trials were the best predictors of YLD. Results indicated that due to genotype by environment interactions not all stress-adaptive traits could be accumulated in a single genotype. In general, day to heading, CTg and grain weight are suggested as indirect selection criteria for increasing YLD under heat and drought stresses. In particular, CTg could be used as a rapid and effective criterion for screening a high number of genotypes.

Using image analysis technology, the morphological measurements of paddy, brown (BR), and milled (MR) grains of 408 rice (Oryza sativa L.) lines representing a wide range of grain morphology were obtained, and the measurements' relationships with grain weight, milling quality, and chalkiness were investigated. The principal component analysis identified two morphological traits with a total variance of 95.7% in MR. Weight of MR was modeled as a function of the principal components using linear regression (R2 = 0.95). For milling quality measurements, dominance analyses indicated that single grain weight of the paddy and BR grains were two primary parameters in determination of BR and MR recovery, whereas surface area, perimeter, and diameter were primary parameters that controlled head milled rice (HR) recovery. All measured morphological properties (surface area, perimeter, diameter, length, width, length-to-width ratio, roundness, and thickness) and grain weight significantly correlated with pe...

The anthracnose stalk rot of corn (ASR), caused by Colletotrichum graminicola, is a major disease of this crop and occurs in most Brazilian regions where corn is grown. Despite its widespread occurrence, there are no estimates of the effect of ASR on the yield of corn under the Brazilian conditions. In this study, we evaluated the effect of ASR on corn hybrids yield. Two experiments were conducted (first crop 2007/2008 and second crop, 2009) in areas with a history of occurrence of leaf anthracnose and ASR. Five hybrids were evaluated in the first and second crops: AG1051, BRS 1001, BRS 1010, BRS 1035, P30F80 and BRS 1010, 2B710, P30F80, DKB390, BRS 1035, respectively. At harvest, we evaluated the incidence of plants with anthracnose stalk rot (IPASR), and we selected pairs of healthy and diseased plants to quantify the effect of ASR in the ear weight (EW), grain weight (GW) and the weight of a sample containing 100 kernels (W100). The IPASR was higher in the hybrid BRS 1010 (21.87 and 45.28%, first and second crops, respectively). The EW, GW and W100 were lower in diseased plants in all hybrids. The mean weight loss in the first season was EW 29.03%, GW 27.83% and W100 17.08%, and the second season was EW 27.75%, GW 25.60% and W100 16.99%. The most affected hybrids with weight loss in the first crop were AG1051 (EW 34.31%, GW 33.05%, W100 19.96%) and BRS 1035 (EW 34.74%, GW 34.65%, W100 22.31%). In the second crop, were P30F80 (EW 30.72%, GW 30.92%, W100 19.24%), DKB390 (EW 30.61%, GW 29.81%) and 2B710 (W100 19.27%). Corn yield was strongly affected by ASR.

Genetic background and Genetic Improvement, Chinese Academy of Agricultural Sciences, effect and environmental sensitivity are two major obstacles for marker-assisted breeding (MAB) Z.J. Xu, Shenyang Agricultural Univ., Dongling Rd. 120, Shenyang of complex traits. Background-independent (BI) loci for 1000-grain weight (TGW) and grain shape tute, DAPO Box 7777, Metro Manila, Philippines. H.W. Mei, Shang(GS) were detected over three seasons using a set of recip-rocal introgression lines (ILs) from Lemont China. T.Q. Zheng and Y. Wang contributed equally to this work. × Teq-ing cross with parents having distinctive GS but equal TGW. Reciprocal ILs in advanced (F 11–13 ) generations were genotyped using 142 polymor-phic simple sequence repeat (SSR) markers on 64 chromosome bins. Nineteen bins of BI loci significantly associated with TGW and/or GS that were identified consistently over multiple seasons and additive effects were in the oppo-site directions at the same loci between two backgrounds. These 19 bins could be classified into three types: Type I includes four genetic overlapping bins affecting both TGW and GS, Type II includes nine genetic overlapping bins controlling GS component traits, and Type III includes six bins for single GS component. Among them, five stably expressed BI loci (bins 2.2,2.5, and3.7forgrainlength[GL] bins5.2and 7.4 for grain width [GW]) found consistently over three seasons would be the first choice for MAB. Secondary choice would be the loci that expressed over at least over two seasons and include bins 1.2, 3.3, 4.3 for GL and bins 7.1 and 11.5 for GW. Two related key traits, one for yield (TGW) and the other for grain quality (GS), can now be fully utilized through marker-aided trans-fer or pyramiding of Published in Crop Sci. 51 (2011).the identified BI loci in rice (

We investigated the effect of elevated [CO2], [O3] and temperature on plant productivity and if these climate factors interacted with each other in multifactor treatments. The climate effects were studied in 14 different cultivars/lines of European spring oilseed rape (Brassica napus L.) and spring barley (Hordeum vulgare L.). Seven genotypes of each species were cultivated in six single- and multifactor treatments with ambient or elevated CO2 (385 ppm and 700 ppm), O3 (20 ppb and 60 ppb) and temperature (12/19 °C and 17/24 °C). Growth and production parameters were measured. Elevated CO2 increased yield and biomass. Seed number increased by about 47 % in barley and by 26 % in oilseed rape, but in oilseed rape, the TSW was significantly decreased, possibly because of shortening of the seed filling period. Higher temperatures decreased yield and biomass significantly in both species. A significantly decreased yield and thousand grain weight was also seen in barley due to elevated O3. The multifactor combination of elevated CO2, O3 and temperature showed a decrease in growth and production in the two species, though not statistically significant for all parameters. This trend suggests that the expected increase in the plant production in northern Europe, indicated by Intergovernmental Panel on Climate Change (IPCC) as a consequence of increased [CO2] and temperature, may not hold, due to interactions between these abiotic factors.

Water is the primary regulator of yield formation in cereals. The effect of water limitation and its timing on development of yield components were studied in detail at spike and spikelet level in spring barley (Hordeum vulgare L.). An experiment with three watering treatments (control watering, CONT; drought prior to pollination, DR1 and terminal drought, DR2) was set up in a large greenhouse (20 x 30 m). In addition to watering treatments, two NPK fertilizer application rates (0 and 120 kg N ha ―1 ) were used to investigate the fertilizer effect. The drought effect exceeded the effect of fertilizer application for grain number and single grain weight (SGW). DR1 reduced the number of grains, whereas DR2 reduced both SGW and the number of grains. Resuming the watering at pollination (DR1) restored photosynthesis and enhanced grain filling, resulting in almost similar SGW in DR1 and CONT plants. Spikelets in the upper mid-section of the spike dominated yield formation in all treatments. This was particularly emphasised in DR1 plants as 58 % of the grain yield was produced in spikelets 3―5, whereas in DR2 and CONT plants it was 39 % and 36 %, respectively. Hence, drought prior pollination strongly reduced yielding capacity (=grain number) in apical and basal spikelets. DR1 and DR2 reduced substantially grain yield and grain N yield resulting in low nitrogen use efficiency.

Milling of oats involves separation of the kernel from its enclosing husk. The ease with which this happens is termed ‘hullability’. The association between morphological characteristics measured using image analysis and hullability was examined in oat varieties sampled from Recommended List variety trials conducted at AFBI Crossnacreevy, Belfast, UK in 2000 and 2006. Grain features of the varieties were distinctive and showed differing relationships with weight, Barra changing only slightly, whilst Mascani showed the maximal changes with increasing grain weight. Hullability was poorer in larger grain, and better in Barra and Mascani than in Gerald and Tardis. Fitting of exponential models for the percentage of hulled grain with dehulling duration identified features associated with different aspects of dehulling behaviour. Greater width of grains of Mascani and Tardis was associated with a more rapid increase in hullability at shorter durations of dehulling. Greater roundness in Barra and Gerald in 2000 was associated with better hullability at very short durations of dehulling relative to other varieties. It is concluded that these features of the grain could be of use in selecting high hullability in breeding programmes.

The stemfly, Melanagromyza phaseoli (Tryon) infests stems of over 95% plants of soybean and damages them from the base up to 30 cm height, although the intensity of damage is confined to 25 cm in a majority of the attacked plants. Various levels of stem damage in stemfly infested plant failed to reveal any significant differences among them. However, infestation by the stemfly in a plant tended to reduce its pod bearing and grain weight in comparison to a healthy plant. Considering significant differences in the mean yield of a healthy and infested plant a net loss of 1.1 g/plant is inevitable even in insecticidal treatments. This loss worked out to 2.33 Qn/ha in 53% plants yielding significantly in an optimum plant population of 400 000/ha. Zusammenfassung Uber den Verlust am Ertrag von Schoten und Samen der Sojabohnen durch die Stengelfliege Melanagromyza phaseoli (Tryon) Melanagromyza phaseoli befallt in Indien mehr als 95% der Sojabohnenpflanzen und beschadigt sie vom Grund bis zu maximal 30 cm, meist 25 cm Hohe. Verschiedene Schadensstufen lassen sich an den Stengeln der Pflanzen nicht sicher unterscheiden, jedoch bieten die Verluste an Schoten und Samen eine gute Bewertungsgrundlage. Insgesamt trat selbst an mit Insektiziden behandelten Pflanzen ein mittlerer Nettoernteverlust von 1,1 g/Pflanze auf, das sind bei einem 53% igen Befall und 400 000 Pflanzen/ha 233 kg/ha.

In Madhya Pradesh, India, the girdle beetle, Oberea brevis Swed., attacked soybean plants on an average of 13.4% in 1969, 34.2% in 1973 and 21.1% in 1974. The attack in itself was responsible for the loss of 29.1% grains as compared to healthy plants. The larvae of both generations girdle the stems from inside to cut off a small portion of the stems for the protection of the diapausing larvae. By this the pod bearing portions of the plants fell down. It was noted that 52.5% of the infested plants were cut down at a mean height of 33 cm, and 21.9% plants at an average height of 6 cm at which the largest number of pods and grains were lost. Another significant cut-off of 15.4% of the plants took place at an average height of 18 cm. A few plants were also cut near the top when the loss of pods and grains was comparatively small. The cut off height of the infested plants was negatively correlated with pod loss (r = –0.755), pod weight (r = –0.900), grain number (r = –0.955) and grain weight (r = –0.625) and a linear relationship was found between them. The weight of the grain from the top-cut portions of infested plants was significantly reduced in relation to that of healthy plants and their germination capacity was also seriously affected. Zusammenfassung Wirkungen des Frases von Oberea brevis Szved. (Col., Cerambycidae) auf Sojabohnen In Madhya Pradesh, Indien, befiel der Ringelungs-Bock, O. brevis, 1969 = 13,4%, 1973 = 34,2% und 1974 = 21,1% der Sojabohnen-Pflanzen. Der Befall fuhrte zum Verlust von i. M. 29,1% des Samengewichts, verglichen mit unbefallenen Pflanzen. Die Larven beider Generationen leben in den Stangen und ringeln diese von innen her, um Teile aus dem Stengel herauszuschneiden, die zum Schutz fur die Larven-Diapause verwendet werden. Hierdurch brechen die oberhalb der Ringelung befindlichen Pflanzenteile ab. Es zeigt sich, das 52,5% der befallenen Pflanzen in einer Hohe von 33 cm, 21,9% in 6 cm Hohe und 15,4% in 18 cm Hohe abgeschnitten wurden, was zu einem nur geringen Verlust an Sojabohnen fuhrte. Die Schnitthohe war negativ korreliert mit der Zahl verlorengegangener Bohnen (r = –0,755), dem Verlust an Bohnengewicht (r = –0,900), der Verminderung der Samenzahl (r = –0,955) und dem Verlust an Samengewicht (r = –0,625). Zwischen diesen Gliedern bestanden lineare Beziehungen. Das Gewicht der Samen der an der Spitze abgeschiedenen Pflanzen war signifikant kleiner als jener von gesunden Pflanzen. Auch war ihre Keimfahigkeit verringert.

Morphological, physical, and chemical properties of grain and flour of 20 chalky rice mutants were compared with those of a translucent parental cultivar, Koshihikari. Compound starch granules were loosely packed and single starch granules were observed in chalky parts of mutant endosperm. Chalky mutant lines were classified into milky-white and white-core lines based on the degree of endosperm chalkiness. Physical and chemical characteristics also suggest a division of chalky mutant lines into two groups, consistent with the classification made based on morphological characteristics. Milky-white mutant lines showed significantly lower grain weight, decreased starch content, and lower grain hardness than white-core mutants and Koshihikari. Rice flour prepared from milky-white mutants by dry milling showed less starch damage and finer mean particle size than white-core mutants and the parent. These results indicated that a loosely packed structure in chalky endosperm was responsible for fragile gr...

BACKGROUND: In the last two decades, newly released rice cultivars in southeastern China have been mainly characterised by more grains per cm panicle (GPCP), i.e. a compact panicle. These compact panicle cultivars show high yield potential but inferior quality. Accordingly, experiments were conducted to study the effect of GPCP on grain weight and quality. RESULTS: Two compact panicle and two loose panicle cultivars of japonica rice were used to investigate the effect of GPCP on the variation in grain weight and quality within a panicle. Significant differences in grain quality, including brown rice length, width and length/width ratio, brown rice and head-milled rice percentages, chalky grain percentage and amylose and protein contents, were found among grains within a panicle. In general, the compact panicle cultivars showed lower grain weight and larger variation in brown rice length, width and length/width ratio, chalky grain percentage and amylose content among grains within a panicle than the loose panicle cultivars. CONCLUSION: GPCP is negatively associated with quality uniformity, and increasing the grain number on top secondary rachises may reduce the variation in grain weight and quality within a panicle. Copyright © 2008 Society of Chemical Industry

In rice-wheat systems, late sowing of wheat is the major reason of low yield. This yield reduction is principally due to lower and erratic germination, and poor crop establishment because of low temperature prevailing. The present study was conducted to explore the possibility of improving late sown wheat performance by seed priming techniques. Seed priming strategies were: on-farm seed priming, hydropriming for 24 h, seed hardening for 12 h and osmohardening with KCl or CaCl 2 for 12 h. Seed priming improved emergence, stand establishment, tiller numbers, allometry, grain and straw yield, and harvest index. However, seed priming techniques did not affect plant height, number of spikelets, number of grains and 1000 grain weight. Osmohardening with CaCl 2 gave more grain and straw yield and harvest index compared with control and other priming treatments, followed by osmohardening with KCl and on-farm seed priming. Improved yield was attributed principally to better stand establishment and improved number of fertile tillers. Seed priming techniques can be effectively used to improve the performance of late sown wheat.

Summary A pot experiment was done in the glasshouse to study the competition between Avena sterilis ssp. macrocarpa Mo. and six wheat cultivars of different lengths of growth cycle. The competitiveness of wild oat was similar for all six wheat cultivars with respect to grain weight, straw weight, number of ears and total accumulation of nitrogen. The cultivar with the longest cycle was the most affected by wild oat competition as regards height, because a large part of its stem extension and some of the heading took place after the panicles of wild oat had expanded. Wild oat competition with wheat plants was greater than the competition among wheat plants themselves. The wild oat had a similar tolerance to all the wheat cultivars.

The primary aim of the present study was to investigate the overexpression of the rice (Oryza sativa L. subsp. japonica var. Zhonghua 11) flowering control gene (rFCA-RRM2) in monocotyledonous model rice. Constitutive expression of rFCA-RRM2 from the Act 1–5 rice promoter caused late flowering in transgenic rice and increased grain weight that was more than 50% higher than that of control plants, which is the first demonstration of rFCA-RRM2 being able to increase rice production. Late flowering was accompanied by strong phenotype and some morphological modifications. These observations suggest that rFCA-RRM2 is a useful tool for phenotype improvement and yield enhancement in cereal crops. (Managing editor: Ping HE)

High temperatures during the grain-filling period (GFP) of rice (Oryza sativa L.) increase the grain dry matter increase rate (GIR), but this increase in GIR is insufficient to completely compensate for the concomitant reduced GFP, and as a result, grain yield decreases. The shortfall in GIR as temperatures increase has been believed to signify a reduction of the potential GIR as a sink capacity. However, we suspect that lack of assimilate supply to the grain, rather than the decreased potential GIR, lowers the GIR and causes reduced grain weight. Our objective was to determine if the grain weight could reach full potential under higher temperature conditions if assimilate supply during the GFP was suffident to sustain the increased GIR. Rice was grown at three locations in western Japan over 3 yr. At one location, plots were covered with plastic film during the GFP to increase temperature. Spikelet filling percentages (F%) at maturity varied between 70 and 90% when mean temperatures ranged between 23 and 29°C during the GFP. When plots were thinned to half density during GFP, all F% were approximated by a single logistic equation based on accumulated temperature, with a ceiling of 90%. Hence, thinning can overcome the lower F%. These results suggest that potential GIR in rice is not reduced by high temperatures during the GFP. Yield reductions commonly associated with such conditions are likely due to the failure of assimilate supply to the grain to meet the requirements of the accelerated GIR.

Knowledge of interrelationships between grain yield and its contributing components will improve the efficiency of breeding programs through the use of appropriate selection indices. Previous path analyses studies in maize (Zea mays L.) treated yield components as first-order variables. The present study, based on evaluation of 90 experimental maize hybrids (comprising one diallel and one line x tester set) at two locations in India, utilizes a sequential path model for analysis of genetic associations among grain yield and its related traits by ordering the various variables in first-, second-, and third-order paths on the basis of their maximum direct effects and minimal collinearity. The sequential path model showed distinct advantages over the conventional path model in discerning the actual effects of different predictor variables. Two first-order variables, namely 100-grain weight and total number of kernels per ear, revealed highest direct effects on total grain weight (p = 0.74 and p = 0.78, respectively), while ear length, ear diameter, number of kernel rows, and number of kernels per row were found to fit as second-order variables. All direct effects were found to be significant, as indicated by bootstrap analysis. Test for the goodness-of-fit revealed that the sequential path model provided better fit to various datasets analyzed in the study. Correlations between the predicted values of various response variables in the second season dataset based on the path coefficients of the first season were high, except for ear length and number of kernels per row. The applicability of the model has been confirmed through analysis of two additional datasets during 2000. The results indicated the utility of the sequential path model for determining the interrelationships among grain yield and related traits in maize.

The effect of heat stress on the components of grain weight was analysed in wheat (Triticum aestivum L.) varieties differing in grain weight stability. The wheat varieties PBW154, Sonalika and Hindi62 were raised in the field (New Delhi, India; 77°12′ E, 28°40′ N, 228.6 m a.s.l.) at three dates of sowing: 19 November 1992 (DOS I), 14 December 1992 (DOS II) and 18 January 1993 (DOS III). The late-sown crop (DOS III) experienced 6–8 °C warmer temperatures during grain development than the crop sown at the normal time (DOS I). The heat susceptibility index (S) revealed that grain weight was less susceptible to heat in Sonalika and PBW154 than in Hindi62. Heat stress reduced both the grain growth duration (GGD) and the grain growth rate (GGR). The grain weight reduction in PBW154 and Sonalika was mainly due to a reduction in GGR, while that of Hindi62 was due to a reduction in GGD. In vivo studies on starch and protein synthesis in excised endosperm at 15, 25 and 35 °C revealed that both processes were more thermotolerant in Hindi62 than in PBW154. The grain starch content was stable in Hindi62 while that in PBW154 was significantly reduced under heat stress. The grain nitrogen content at maturity increased in both varieties under heat stress. It was concluded that the heat susceptibility of grain weight in Hindi62 was mainly due to a reduction in GGD, although GGR, starch and protein synthesis were more thermotolerant in developing grains of Hindi62 than in those of PBW154. Einfluss von Hitzestress auf das Kornwachstum, Starke und Proteinsynthese in Kornern von Weizen (Triticum aestivum L.)-Sorten mit unterschiedlicher Korngewichtsstabilitat Der Einfluss von Hitzestress auf die Komponenten des Korngewichtes wurden bei Weizen (T. aestivum L.)-Sorten unterschiedlicher Korngewichtsstabilitat untersucht. Weizenvarietaten viz. PBW154, Sonalika und Hindi62 wurden unter Feldbedingungen (New Delhi, India, 77°12′E, 28°40′N, 228,6 m) an drei Terminen, 19.11.1992 (DOS I), 14.12.1992 (DOS II) und 18.01.1993 (DOS III) angesat. Die spate Aussaat (DOS III) unterlag 6–8 °C warmeren Temperaturen wahrend der Kornentwicklung im Vergleich zu den normal Terminen angesaten Bestanden. Hitzeempfindlichkeitsindex (S) zeigte, dass das Korngewicht toleranter bei Sonalika und PBW154 war im Vergleich zu Hindi62. Der Hitzestress reduzierte die Kornwachstumsdauer (GGD) und die Kornwachstumsrate (GGR). Die Reduktion im Korngewicht bei PBW154 und Sonalika war im wesentlichen eine Folge der Reduktion von GGR, wahrend die Korngewichtsreduktion von Hindi62 eine Folge der Reduktion in GGD war. In vivo-Untersuchungen bezuglich Starke und Proteinsynthese in separiertem Endosperm bei 15 °C, 25 °C und 35 °C zeigte, dass beide Prozesse thermotoleranter bei Hindi62 als bei PBW154 waren. Der Kornstarkegehalt war bei Hindi62 stabil, wahrend der Kornstarkegehalt von PBW154 signifikant unter Hitzestress reduziert wurde. Der Stickstoffgehalt des Korns zur Reife nahm in beiden Varietaten unter Hitzestress zu. Es kann angenommen werden, dass die Hitzeempfindlichkeit des Korngewichtes bei Hindi62 wesentlich eine Folge der Reduktion von GGD war, obwohl GGR Starke und Proteinsynthese thermotoleranter in den sich entwickelnden Kornern von Hindi62 im Vergleich zu PBW154 waren.

Grain dry weight, water content and changes in wall-bound α-galactosidase and β-glucosidase activities were estimated in three grains (differing in their position on the spike and final dry weight) of wheat (Triticum aestivum L.) cultivar Lok-1 during the entire period of grain development. Considerable differences in the grain weight within a wheat spike are reported, but the physiological and biochemical bases of these differences are poorly understood. The experiments described here indicate that the maximum grain weight is dependent upon the rate of grain filling. A highly significant correlation (P < 0.001) between maximum grain weight and maximum water content per grain, and a close correspondence between the rate of grain filling and wall-located α-galactosidase activity, suggests that the process of cell enlargement may be important in determining the rate of grain filling, and thus, for maximum grain weight in wheat.

Isogenic lines were developed in order to assess the precise effects of the 1BL/1RS translocation on quality characteristics and agronomic traits. Results showed that the translocation has a detrimental effect on sodium dodecyl sulphate sedimentation volume, in any background. Yield was similar between translocated and non-translocated lines; however, lines carrying 1BL/1RS showed a significant increase in grain weight, together with a decrease in spike number per plant.

The development of grains of different positions in the apical, middle and basal spikelets of wheat var. Kaly-ansona showed that beyond first two basal grains, the more distal a grain in a spikelet the lower its weight. The distal grains received less assimilates than the proximal grains as revealed from sugar concentration in the grains. The efficiency of distal grains of kalyansona to synthesize reserves was, however, not inferior than the proximal grains in a spikelet. The depression in grain weight towards extreme spikelet was lower compared to the depression in weight of individual grains towards a distal position in a spikelet. The study seems to suggest that in order to ensure better grain uniformity while maintaining a higher grain number per ear, the spikelet number per ear should be increased instead of increasing the grain number per spikelet.

Semidwarf genes have made a major contribution to grain yield gains in wheat during this century. These genes have frequently been reported to increase grain number but decrease grain size. To analyse possible causes of this negative association between number of grains per head and mean grain weight, grains from different positions within the spikes were individually weighed in three isolines (standard-height, SH; semidwarf, SD; and dwarf, DD) of the spring wheat cultivar Maringa grown under field conditions. Dwarfing genes affected both grain number and grain weight. Increasing doses of Rht genes resulted in a decreased average grain weight (ca. 22 %) but in a greater increase in number of grains per m2 (ca. 40%). Since the isogenic lines did not differ in either the number of spikes per m2 or number of spikelets per spike, the frequencies of appearance of grains in the distal positions (florets 3 and 4) of the central spikelets and in the top spikelets of the spike was much higher for the SD and DD lines than for the SH line. Averaging across spikelets, basal grains (grains 1 and 2) of SH, SD and DD lines represented ca. 82, 73, and 69 %, respectively, of the total number of grains. On the other hand, grain 4 was almost absent in the SH line but represented around 10 % of the grains in the DD line. Averaging across lines and spikelets, basal grains weighed ca. 30 mg, which is approximately 20 % heavier than grain 3 (ca. 25 mg) and 85 % heavier than grain 4 (ca. 16 mg). Although there was a clear trend for a greater grain weight in the SH line (with no major differences between the SD and DD line) when basal grains were considered, grains 3 and 4 did not show any clear difference between lines. The fact that genotypes with Rht alleles had grains in the distal positions with a much higher frequency of appearance than in the SH line could be the main reason for their lower average grain weight. Therefore, the negative relationship between grain number and average grain weight might be not reflecting that competition for assimilates among grains of the DD and SD lines is stronger than that in the SH line.

The vast majority of the world's acreage of semi-dwarf wheat varieties is at present cultivated with varieties carrying one of two genetically similar dwarfing genes, Rht1 and Rht2, derived from the Japanese variety ‘Norin 10’. Near-isogenic lines have been developed and tested to determine the breeding potential of an allelic variant of Rht1, designated Rht1(B. dw). Following its introduction into four varietal backgrounds, Rht1 (B. dw) was seen to reduce height by around 25%, to increase the number of grains setting in spikelets and ears by around 20%, to reduce grain weight by 10%, and to increase yields of plants grown under spaced or drilled conditions by about 8%. When compared to the commercially utilized Rht1 allele, as near isogenic lines in a ‘Mercia’ varietal background, Rht1 (B. dw) gives a significantly greater reduction in plant height, a greater increase in spikelet and ear fertilities, slightly less reduction in 1000-grain weight, and significantly higher spikelet, ear and plot yields. If these results are repeatable in other varietal backgrounds, over seasons, and under differing environmental conditions, Rht1 (B. dw) should have considerable commercial potential as an alternative allele for producing shorter-than-average, high-yielding, semi-dwarf wheat varieties.

Grain yield and some of its physiological determinants were analysed in a field study conducted over two growing seasons with standard-height (SH), semi-dwarf(SD) and dwarf (DD) isogenic lines ofa spring wheat sown at recommended and delayed dates. The objective was to test whether the action of Rht1 and Rht2 alleles in improving grain yield depended upon sowing date. As expected, the dwarfing genes significantly reduced plant height in both sowings and growing seasons. There was a tendency for the SD line to produce more biomass than the SH and DD lines, although the differences were mostly not significant. Harvest index was linearly and negatively related to plant height. Consequently, the SD and SH line showed the highest and lowest grain yields in all environments. The optimum height for grain yield was estimated to be c. 70 cm, and this value was not affected by sowing date. Lines carrying Rhtl and/or Rht2 alleles always showed more grains/m 2 (owing to an increased number of grains per spike and spikes/m 2 ) than the SH line. Conversely, average grain weight was negatively associated with the number of grains/m 2 . Because the slope of this negative relationship was smaller (less negative) than that representing complete compensation, the relationship between grain yield and number of grains/m 2 was hyperbolic. Although these relationships are frequently regarded as a reflection of increased competition among grains when the number of grains/m 2 is increased owing to the use of semi-dwarf genes, two alternative hypotheses are analysed and discussed.

In order to investigate the significance of seed source on yield and related characters 47 seed lots of seven faba bean varieties and 24 seed lots of five dry pea varieties were tested in three series of field trials. The grain yield of the faba bean varieties tested was considerably modified by seed source, whereas only small and non-significant effects of seed source were found in dry peas. In general, seed sources with a high thousand grain weight, a high protein content, high portions of undamaged and healthy seeds, and in faba beans a high degree of cross-fertilization exhibited superior grain yields. Production of high-performance seed proved to be the most difficult for the large-seeded and white-flowered faba bean varieties. Based on a tabular summary on factors affecting effects of seed source problems of seed production in both grain legumes and their impact on yield are discussed

Rice(Oryza sativa L.) milling quality is a complex trait and influenced by many factors including the uniformity of grain filling and other grain characteristics. Although much is known concerning genotypic differences in rate and duration of grain filling, quantitative information on uniformity or non-uniformity of grain filling and kernel characteristics on the panicle is lacking. This study investigated and compared the degree of non-uniformity of grain filling among 6 rice cultivars of different grain types, maturities, and the plant characteristics that may influence the uniformity of grain filling. Models of grain growth and rate of growth were developed for grains on the upper, middle and lower parts of the panicle. Non-uniformity of grain filling parameters (duration and rate of grain filling, maximum grain weight) were estimated and compared among cultivars of different grain types and maturities. Results showed that, in general, grain size and rate of filling decrease from upper part to the lower part of the panicle. The ranges among grain growth curves from the upper, middle and lower parts of the panicle of the very early, and early maturing cultivars were greater than those of intermediate and late maturing cultivars. However, non-uniformity of grain filling is not necessarily a function of maturity. Plant and grain characteristics such as even distribution of grain size, high grain filling rate between 10–15 days after heading, and optimum weight ratio of panicle to above-ground leaf and stem matter may be selected for by breeders to improve the uniformity of grain filling, independent of maturity. Zusammenfassung Uniformitat der Rispenentwicklung von Reiskultivaren mit unterschiedlichen Rei-fezeiten Die Reis (Oryza sativa L.)-mahlqualitat ist eine komplexe Eigenschaft und wird von zahlreichen Faktoren, einschliesilich der Einheitlichkeit der Kornfullung und anderer Korneigenschaften beeinslufk. Obwohl zahlreiche Informationen bezuch genotypischer Differenzen hinsichtlich der Rate und der Dauer der Kornfung bekannt sind, besteht ein Mangel an Informationen hinsichtlich der Einheitlich-keit oder Uneinheitlichkeit der Kornfung und von Korneigenschaften der Rispe. Die vorliegende Untersuchung vergleicht den Grad der Uneinheitlichkeit der Kornfullung von sechs Reiskultivaren unterschiedlichen Korntyps, unterschiedlicher Reife und unterschiedlicher Pflanzeneigenschaften, die Einflufs auf die Einheitlichkeit der Kornfullung nehmen konnen. Modelle fur Kornwachstum und Wachstumsrate wurden fur Korner des oberen, mittleren und unteren Abschnitts der Rispe entwickelt. Uneinheitlichkeit der Kornfullung (Dauer und Rate der Fullung sowie maxi-males Korngewicht) wurden geschatzt und mitden Kultivaren unterschiedlichen Korntyps und unterschiedlicher Reife verglichen. Die Ergebnisse zeigen, das die Korngrose und Kornfullungsrate grundsatzlich vom oberen zum unteren Teils der Rispe sehr fruher und fruher Kultivare waren groser als diejenigen der Kultivare mittlerer und spater Reife. Allerdings ist Uneinheitlichkeit der Kornfullung nicht zwingend eine Funktion der Reife. Pflanzen- und Korneigenschaften, wie z. B. gleichmasge Verteilung der Korngrase, hoher Kornfullungsrate zwischen dem 10. bis 15. Tag nach dem Rispenschieben sowie ein optimales Verhaltnis des Gewichtes der Rispe zu dem oberirdischen Pflanzenteil an Blatt-und Sprosmasse konnen fur die Selektion vom Zuchter verwendet werden, um die Einheitlichkeit der Kornfullungsphase unabhangig von der Reife zu verbessern.

Variation was investigated in 110 doubled haploid (DH) lines of wheat derived from wheat × maize crosses. Field observation revealed visible variations in 15 DH2 lines such as extreme dwarfism, low seed fertility, alteration of spike type and stripes. Six agronomic traits, i.e., heading date, spike number/ plant, culm length, spike length, seed fertility and grain weight were statistically analyzed in the DH2 and DH3 generations. Out of the 88 DH2 lines/DH3 groups, 26 %/64 % showed significant differences from the parental variety in the means of one or more traits. Ranges of the DH3 lines were larger than those of the DH2 lines, except for spike number/plant. Furthermore, analyses of variance within and between DH lines showed the presence of heterogeneity/heterozygosity in the DH2 lines/plants. These results indicated the occurrence of gametoclonal variation in the DH lines. It is considered that most of the variations detected were due to the colchicine treatment rather than to the 2,4-D treatment or in vitro culture.