Association of Grain Shedding Habit with Polyploidy in Tartary Buckwheat (Fagopyrum tataricum) Strains

Abstract

Sixty tartary buckwheat (Fagopyrum tataricum) strains were investigated for grain shedding habit, plant height, grain yield, dry weight of plant, weight of grain, days to flowering after sowing and DNA content of nuclei. The grain shedding habit was evaluated from the breaking strength of pedicel and the percentage of the grains dropped by threshing. DNA content of nuclei was detected by flow cytometry to classify the polyploidy level. The fluorescence intensity of the flow cytometry demonstrated no difference between common buckwheat (F. esculentum) and tartary buckwheat, but a clear difference was detected between the diploid and the autotetraploid strains. The survey of DNA content of the 60 tartary buckwheat strains revealed that most of the strains were diploids, but one strain was autotetraploid. The autotetraploid strain exhibited less grain shedding, and produced the largest grains among the strains tested. However, the other characters of the autotetraploid strain, such as plant height, grain yield, dry weight of a plant, and days to flowering, were similar to the mode of the traits of the diploid strains.     

Breaking Strength of Pedicel as an Index of Grain-Shattering Habit in Autotetraploid and Diploid Buckwheat (Fagopyrum esculentum Moench.) Cultivars

Abstract

The grain-shattering habit was compared among diploid and autotetraploid cultivars of common buckwheat (Fagopyrum esculentum Moench.). In the first experiment, one diploid and one autotetraploid cultivar were grown in the field, and the number of grains shed naturally by wind or rain, and the number of grains detached by threshing the plants (by dropping from 1 m height onto a concrete floor, five times) were measured to evaluate grain shattering. The number of the naturally shed grains in the field was higher in the diploid than in the autotetraploid cultivar, although the number of grains detached by threshing was not different between the two cultivars. In another set of experiments, breaking bending strength and breaking tensile strength of pedicels were measured as indices of grain-shattering habit to examine the difference in shattering among two autotetraploid and four diploid cultivars (two summer types and two autumn types). They were grown in summer and autumn seasons to examine the environmental effect on grain shattering. Both breaking strengths were about two times higher in the autotetraploid cultivars than in the diploid cultivars. The breaking strength was well correlated with the diameter of pedicels. The values of grain-shattering resistance traits obtained in the autumn cropping season were higher than those obtained in the summer cropping season.     

Morphological Evaluation of the Trace of Grain Detachment in Japonica Rice Cultivars with Different Shattering Habits

Abstract

Seed shattering is an important agronomic trait in rice as it directly affects the yield. Manipulation of the degree of shattering will maximize the yield potential. This study was performed to find an indicator for indirect selection to facilitate the selection of medium-shattering habit in japonica rice breeding. The grain shattering pattern and microscopic morphology of the separation zone on pedicels of five japonica rice cultivars with different shattering habits were compared. Almost all grains were separated between the sterile lemma and rudimentary glume in cultivars with medium-shattering, easily-shattering and very easily-shattering habits. On the other hand, approximately 50% of the grains of the cultivar with hardly-shattering habit were torn off at the bent portion of pedicel. A separation pileus was formed on the terminal of the pedicel. The pileuses were most prominent in cultivars with easily-shattering and very easily-shattering habits, while cultivars with a medium-shattering habit had more flat pileuses than prominent pileuses. Additionally, in the cultivar with a hardly-shattering habit all pileuses were flat. Development of fibrous cell walls on the separation pileus varied with degree of shattering habit. The easier the grain shattered, the poorer was the development of fibrous cell walls. These results strongly suggest that the shape of separation pileus and the development of fibrous cell walls are related to the shattering habit in japonica rice. Additionally, it is highly probable that the medium-shattering habit is characterized by the type of shattering that separates between sterile lemma and rudimentary glume with the flat shape of pileus.     

Relationship between stem characteristics and lodging resistance of Tartary buckwheat (Fagopyrum tataricum)

ABSTRACT

Stem lodging can limit the grain yield of Tartary buckwheat (Fagopyrum tataricum), and creates difficulties in harvesting. A 2-year study was conducted to study the relationships between stem characteristics and lodging resistance in Tartary buckwheat. Six Tartary buckwheat cultivars with three stem types (short-stemmed XQ1 and CQ1; mid-length stemmed YQ1 and QK3; and tall-stemmed DAB and DN1) were used. The stem characteristics differed significantly among the three stem types. Mid-length stems had the thickest stem wall, the greatest numbers of large and small vascular bundles, and the lowest stem diameter/stem wall thickness ratio among the three stem types. Mid-length stems had the highest stem breaking strength (SBS) and stem puncture strength (SPS) among the three types of stem. The lignin content was significantly higher in mid-length stems than in tall and short stems. The activities of phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL), and cinnamyl alcohol dehydrogenase (CAD), but not 4-coumarate: CoA ligase (4CL), differed significantly among the three stem types. In correlation analyses, SBS was significantly positively correlated with stem diameter, stem wall thickness, and the number of large and small vascular bundles, but significantly negatively correlated with stem diameter/stem wall thickness and lodging rate. The lignin content was significantly positively correlated with the activities of lignin-related enzymes and with SBS and SPS, and significantly negatively correlated with lodging rate. The present study provides preliminary insights into the relationship between stem traits and lodging resistance in Tartary buckwheat, laying a foundation for a further understanding of lodging resistance.     

Effect of planting density on lodging-related morphology,lodging rate,and yield of tartary buckwheat (Fagopyrum tataricum)

Increase of planting density has been widely used to increase grain yield in crops. However, it may lead to higher risk of lodging hence causing significant yield loss of the crop. To investigate the effects of planting density on lodging-related morphology, lodging rate (LR), and yield of tartary buckwheat, an experiment was carried out with a split-plot randomized block design at the experimental farm of Chengdu University (Sichuan, China) in the 2012 and 2013 growing seasons. Results showed that plant density significantly affected characteristics of stem and root. In each season, with the increasing of planting density, light transmittance, main root length, number of first lateral root, root volume, internode number, and first internode diameter decreased, the plant height, first internode length, abortion rate and LR increased. Increasing density caused decreased grains number per plant, the dry matter weight and yield displayed an acceleration first and then deceleration. The correlation analysis indicated that the internode number, first internode diameter, number of first lateral roots, and root volume were significantly negatively correlated with LR, but positively correlated with stem breaking strength and lodging resistance index. The LR was significantly positively correlated with plant height and first internode length. In both years, the D2 (9 × 10⁵ plant ha^?1) and D3 (12 × 10⁵ plant ha^?1) yielded more grains than in other treatments, and the effects of density on two cultivars showed the same trend. The results suggested that planting density could alter lodging-related traits, lodging resistance, and yield of tartary buckwheat.     

Contribution of flavonoids to the antioxidant properties of common and tartary buckwheat

The objective of this study was to characterize the flavonoid compounds found in the different grain parts of common and tartary buckwheat, and to determine the contribution of these flavonoids to the antioxidant properties of buckwheat. Eight flavonoid compounds were quantified and their antioxidant activity determined by FRAP, DPPH, and ABTS assays. Of the flavonoid compounds identified rutin was the most abundant, particularly in tartary buckwheat, in which it comprised approximately 90% of total flavonoid content. Flavan-3-ols were detected in common but not tartary buckwheat, and quercetin was detected only in tartary buckwheat. Flavonoid content—in particular, levels of rutin, orientin, and/or epicatechin gallate—was found to influence the total antioxidant activity of buckwheat. Results from this study indicate that antioxidant activity is not only closely associated with flavonoid content, but that different flavonoids contribute differently to the total antioxidant activity of common and tartary buckwheat.     

Accurate Evaluation of Photoperiodic Sensitivity and Genetic Diversity in Common Buckwheat under a Controlled Environment

Abstract

Photoperiodic sensitivity is one of the most important factors determining whether a crop can adapt to and be cultivated under a broad range of conditions. In common buckwheat (Fagopyrum esculentum Moench), flowering time (flowering of the first flower) is a complex trait influenced by photoperiod, light quality, and temperature, which change daily under natural conditions, and their interaction. Common buckwheat shows a large genetic variation because of the outcrossing reproductive strategy of this species. Thus, flowering time variation within a population reflects both environmental and genotypic variations, and accurate evaluation of photoperiodic sensitivity in common buckwheat requires cultivation under controlled environmental conditions. Here, we investigated photoperiodic sensitivity and its genetic diversity in two buckwheat cultivars, the autumn ecotype Miyazakizairai and the summer ecotype Botansoba, by controlling photoperiod during cultivation under the same temperature regime. Our results showed that (1) the summer ecotype consisted of early-flowering genotypes, including genotypes not found in the autumn ecotype; (2) the autumn ecotype consisted of various genotypes, including early-flowering genotypes and a large number of late-flowering genotypes not found in the summer ecotype; (3) the autumn ecotype showed larger genetic diversity than the summer ecotype in long-day treatments; and (4) genetic diversity first became evident in the 14.5-hr photoperiod in the autumn ecotype, and in the 15.0-hr photoperiod in the summer ecotype. These results support the hypothesis based on previous studies that common buckwheat summer ecotypes were derived from autumn ecotypes by adaptation to climate in northern Japan.     

Effect of additives on flavonoids, d-chiro-Inositol and trypsin inhibitor during the germination of tartary buckwheat seeds

In this study, we evaluated tartary buckwheat during germination to provide an effective process that can lead to a rapid accumulation of both the total flavonoids and d-chiro-Inositol (DCI), as well as the elimination of trypsin inhibitor activity. At different concentrations of Al³⁺, Cu²⁺, and Zn²⁺, we found significant differences of the total flavonoids and DCI accumulation, and we observed changes in phenylalanine ammonia-lyase (PAL), chalcone isomerase (CHI), and α-Galactosidase (α-Gal) activities in germinated tartary buckwheat (p < 0.05). Correlation analysis between these enzymes (PAL, CHI and α-Gal) activities and the total flavonoids and DCI contents revealed a significant correlation in germinated tartary buckwheat. The maximum accumulation of the total flavonoids and DCI were 1315.52 mg/100 g DW and 60.46 mg/g DW with the addition of Al³⁺, 1315.41 and 63.59 with the addition of Cu²⁺, and 1189.42 and 53.10 with the addition of Zn²⁺. In these metal-treated samples, both total flavonoids and DCI were significantly higher than in the control (p < 0.05). Moreover, the metallic additives at the optimum concentration had no influence on total protein content, whereas a lower trypsin inhibitor activity was observed in correlation with higher protein digestibility.     

Factors in the Reduction in Grain Number in Winter Wheat by Early-Sowing in Yamaguchi

Abstract

Grain number per spike of wheat is lower in early sowing than in the conventional standard cultivation in Yamaguchi, Prefecture, Japan. Components of the grain number per spike in five cultivars were analyzed with respect to temperature during the spike development period throughout three growing seasons 2001/2002, 2002/2003 and 2003/2004 to find the cause of the problem of early sowing cultivation. The plants sown in early-October and late-November were called the early sown group and the standard group, respectively, in the following. Three of the five cultivars, Hokushin, Akitakko and Nanbukomugi, showed a strong winter habit, which requires very cold temperatures for spike differentiation. The other two cultivars, Iwainodaichi and Airakomugi, had a moderate winter habit. Grain number per spike and grain yield were decreased by early-sowing (compare with the standard group) in almost all cultivars throughout the three growing seasons. The three cultivars which had a strong winter habit had fewer spikelets per spike in the early-sown group than in the standard group. The other two cultivars which had a moderate winter habit had fewer grains per spikelet in the early-sown group. The higher the temperature during the spikelet formation phase, which is from flag leaf initiation to terminal spikelet initiation, the higher the number of spikelets per spike in the standard group. The spikelet number per spike in the early-sown group increased with the increase in productive tillers under fertile conditions. Such conditions also increased the grain number per spike.     

Varietal Differences in Cell Wall β-(1→3),(1→4)-Glucan and Nonstructural Carbohydrate in Rice Stems during the Grain Filling Stage

Abstract

The contribution of cell wall components and nonstructural carbohydrate (NSC) to grain filling in rice (Oryza sativa L.) was clarified by investigating the differences in the dynamics of hemicellulose, sugar composition of hemicellulose, β-(1→3),(1→4)-glucan, and NSC among cultivars with different grain filling capacities. This investigation was performed using the stems of standard, high yield and low harvest index (HI) cultivars. Hemicellulose concentration in stems tended to decrease slightly during the grain filling stage. This decrease was attributed to a decrease in β-(1→3),(1→4)-glucan concentration, which was detected as a decrease in glucose composition of hemicellulose in the stems during the grain filling stage. The rate of decrease and decrease in the amount of β-(1→3),(1→4)-glucan in the stems differed among the cultivars. These were higher in high yield and high HI cultivars than in relatively low yield and low HI cultivars. Moreover, a positive correlation was observed between the rate of decrease in β-(1→3),(1→4)-glucan and NSC, indicating similarities in the dynamics of β-(1→3),(1→4)-glucan and NSC among the cultivars. When the top half of panicle was removed, β-(1→3),(1→4)-glucan and NSC concentrations in the culm and leaf sheath did not decrease during the grain filling stage. Therefore, the β-(1→3),(1→4)-glucan in stems might be one of the sources that supply substrate to panicle as well as NSC.     

Evaluation of Cultivar Differences in Preharvest Sprouting of Common Buckwheat (Fagopyrum esculentum Moench)

Abstract

Preharvest sprouting of buckwheat (Fagopyrum esculentum Moench) is an important problem, but cultivar differences in preharvest sprouting and their causes have not been investigated. We detected cultivar differences under natural field conditions. Preharvest sprouting of three cultivars was significantly lower than that of the current main cultivar. Seeds collected before rainfall were threshed and incubated on a wet filter paper in a petri dish for 10 days at 10, 20, 30 and 40ºC in the dark, or at an alternating light and temperature condition of 8 h light at 30ºC and 16 h darkness at 20ºC. Germination was promoted by a higher temperature except for 40ºC, suggesting that the risk of preharvest sprouting in buckwheat is higher at a relatively higher temperature. The risk of preharvest sprouting in the field was highly correlated with germination at 20ºC (r = 0.98***) and 30ºC (r = 0.99***) in the dark, suggesting that germination test can be used to predict preharvest sprouting in the field. Preharvest sprouting was significantly correlated (r = ?0.77**) with main stem length, suggesting that ecotype is partly responsible for this phenomenon.     

Effects of Preharvest Sprouting on Flour Pasting Viscosity in Common Buckwheat (Fagopyrum esculentum Moench)

Abstract

Rain before harvest often causes buckwheat to sprout. Preharvest sprouting reduces the processing suitability of buckwheat flour. We examined the effects of preharvest sprouting on buckwheat flour quality by rapid visco-analysis (RVA) of milled sprouting grains of six buckwheat cultivars. Both artificial and natural rainfall increased the frequency of sprouting and decreased pasting viscosity. The difference in pasting viscosity between sprouting and non-sprouting buckwheat grains was not decreased by adding wheat flour. These results suggest that the mechanical characteristics of dough and boiled noodle may be affected by flour made from sprouting grains. Differing responses of the cultivars to rainfall indicate that higher pasting viscosity could be achieved by using cultivars that are resistant to preharvest sprouting caused by rain.     

Studies on Agronomic Traits of African Rice (Oryza glaberrima Steud.): IV. Changes in growth,dry matter productivity and yielding ability related to domestication from wild to cultivated form

Abstract

The changes in growth, dry matter productivity and yielding ability in the course of domestication from O. breviligulata to African rice (O. glaberrima) were examined. Between the two rice species, differences were hardly detected in plant height, culm length and final leaf number, although O. breviligulata had a wider variation of these characteristics as compared with African rice. The shorter strains tended to produce more tillers at the maximum tiller number stage, and the high tillering capacity was correlated with a low percentage of productive tillers, although the strains having a small number of grains per head showed a high percentage of productive tillers, in both species. No significant difference was detected between the two species in straw weight at maturity, and the differences in straw weight among strains were attributed to the differences in days required from transplanting to heading and to plant height. No significant difference between the two species was observed in top and total weights. The grain number per head was conversely related with panicle number in both species. Although the percentage of ripened grain tended to be slightly lower in O. breviligulata than in African rice, this may be attributed partly to the difference in grain number per hill. Single grain weight in O. breviligulata was nearly equal to that in African rice. These results suggest that agronomic traits such as growth, dry matter productivity and yielding ability have been changed only slightly in the course of domestication from O. breviligulata to African rice.     

Differences in the Ratios of Cyanidin-3-O-glucoside and Cyanidin-3-O-rutinocide to Total Anthocyanin under UV and Non-UV Conditions in Tartary Buckwheat(Fagopyrum tataricum Garten)

Abstract

Anthocyanins play beneficial roles in plant growth and development such as the reduction of photo-oxidative damage to leaf cells. Tartary buckwheat contains two anthocyanins, namely, cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside, which are accumulated in the stems and leaves. In order to clarify which type of anthocyanin is accumulated at different nodal positions, we investigated the type of anthocyanin and their contents in buckwheat stems using HPLC. The anthocyanins detected were identified as cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside by comparison with the retention times and co-chromatography with the standard solutions. The contents of cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside at the proximal stem position were higher than those at the distal stem position. The ratio of each anthocyanin to total anthocyanin varied with the nodal positions. An outdoor study suggested that UV stress might influence the ratio of each anthocyanin to total anthocyanin. Consequently, we investigated these ratios in a growth chamber. The growth chamber study suggested that the ratio of cyanidin-3-O-rutinoside to total anthocyanin was higher under UV conditions than under non-UV conditions. These results indicate that cyanidin-3-O-glucoside accumulates in a small amount and that cyanidin-3-O-rutinoside accumulates in a large amount in young organs that suffer from strong UV stress. Cyanidin-3-O-rutinoside may have a UV-protective effect and tartary buckwheat may accumulate cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside systematically to afford effective protection against UV stress.     

不同氮肥用量下苦荞灌浆特性及根系形态与充实度变化

以苦荞品种‘晋荞2号’为试验材料,设置不同的氮肥处理,研究了氮肥对苦荞灌浆特性、根系形态、农艺性状、充实度及产量的影响。结果表明:中浓度氮肥处理(MN)对晋荞2号籽粒增重效果最显著;籽粒灌浆过程中的实际百粒重、百粒重理论可能最大值(A)、灌浆起始势(R0)、生长速率为最大时的生长量(Wmax·G)及活跃生长期均以MN处理最高;根系长度、表面积、体积均以MN处理最高,根冠比以低浓度氮肥处理(LN)最高;‘晋荞2号’的农艺性状、充实度及产量各指标基本以LN、MN处理最佳。综上所述,中浓度氮肥处理更利于促进苦荞的灌浆进程,进而提高充实度及产量。本研究为苦荞的高产栽培提供了理论依据和技术支撑。     

Genetic Variations in Dry Matter Production,Nitrogen Uptake,and Nitrogen Use Efficiency in the AA Genome Oryza Species Grown under Different Nitrogen Conditions

Abstract

To clarify the genotypic variation of nitrogen (N) response in the AA genome Oryza species, we investigated dry matter production, N uptake, N and water use efficiencies (NUE and WUE), bleeding sap rate (BR), and root morphological traits at vegetative stage in 6 cultivars and 4 strains of 6 species (O. sativa, O. glaberrima, O. barthii, O. nivara, O. meridionalis, and O. rufipogon) grown under standard N (SN) and low N (LN) conditions. Some wild Oryza strains and O. glaberrima showed high dry matter production under both N conditions. In most plants, total dry weight decreased and root dry weight increased under the LN condition, resulting in decreased top-root ratio. In japonica cultivars of O. sativa, however, these traits were unaffected by the N condition. There were no significant differences in WUE with plant species or N conditions. In all plants, however, NUE was higher in the LN than SN condition, and was conspicuously high in most wild Oryza species and O. glaberrima. Some of them showed increased capacity of nitrate-N (NO₃-N) uptake under the LN condition. In cultivars and strains with a high NUE, root dry weight, root surface area, and BR were also higher under the LN condition. These results suggest that a high NUE is associated with the development of a root system, increased BR, and probably increased capacity of NO₃-N uptake. This study revealed the presence of superior wild Oryza strains for growth under LN that may be a promising genetic resource for low N-input agriculture.     

Yield Potential and Physiological and Morphological Characteristics Related to Yield Performance in Oryza glaberrima Steud.

Abstract

Oryza glaberrima has mostly been used as a source to improve stress resistance of Oryza sativa. Improvement of this species could be an approach to use its adaptability to local environments in Africa such as multiple resistance to several indigenous constraints. The yield of O. glaberrima was inferior to that of O. sativa under favorable growth conditions but not under unfavorable conditions. Moreover, spikelet number before grain shattering was no less in O. glaberrima than in O. sativa at any fertilizer input levels, suggesting that the yield potential of O. glaberrima is as high as that of O. sativa. Inferior yield of O. glaberrima reported in favorable environments could result from grain shattering enhanced by such growth environments where higher incidence of lodging, which is another undesirable character of O. glaberrima, can occur. Regarding characteristics associated to yield generation, O. glaberrima seemed to possess: higher dry matter production and greater leaf area than O. sativa at least until heading; a lower photosynthetic rate per leaf area but a higher rate against the same leaf nitrogen content in a low content range; higher responsiveness of dry matter, leaf area and leaf photosynthesis to increases in nitrogen inputs; lower water-use efficiency on dry matter accumulation and gas exchange bases; faster progress of leaf senescence during maturity; and faster completion of grain filling during maturity than O. sativa.     

Development of a High-Performance Liquid Chromatography Method to Determine the Fagopyrin Content of Tartary Buckwheat (Fagopyrum tartaricum Gaertn.) and Common Buckwheat (F. esculentum Moench)

Abstract

Buckwheat contains fagopyrin, which induces photosensitization in light-skinned livestock when exposed to sunlight. Here, we developed a high-performance liquid chromatography (HPLC) method to measure the fagopyrin content of buckwheat. The HPLC profile of the fagopyrin extract purified from Tartary buckwheat ‘Rotundatum’ had 3 apparent peaks. The ultraviolet-visible (UV-vis) absorption spectrum of each peak yielded absorbance maxima ( λ_max) at 547 nm and 591 nm, indicating that these peaks corresponded to fagopyrin and unidentified fagopyrin derivatives. We considered the total content reflected by the 3 peaks to be the fagopyrin content of buckwheat. We determined the fagopyrin content in the leaves of Tartary buckwheat ‘Rotundatum’ and common buckwheat ‘Miyazakiootsubu’ both by UV-vis photometric analysis and the newly developed HPLC method. The fagopyrin content is overestimated by UV-vis photometry because the extracts contain a considerable amount of chlorophyll. Thus, HPLC analysis is more efficacious for fagopyrin-content measurements than UV-vis photometric analysis. The HPLC analysis of fagopyrin is easy, quick and efficacious for screening buckwheat varieties with trace or no fagopyrin. There are only a few reports on the accumulation sites of fagopyrin in buckwheat. We revealed that in Tartary and common buckwheat, fagopyrin is present mainly in the leaves and flowers and slightly in the stems, hulls, and groats. The fagopyrin contents of the leaves and flowers of Rotundatum were approximately 2.6 and 2.8 times higher than those in Miyazakiootsubu, respectively.     

Consideration of peg strength and disease severity in the decision to harvest peanut in southeastern USA

The indeterminate nature and underground fruiting habit of peanut (Arachis hypogaea L.) makes it a challenge to determine the optimal harvest time. The objectives of this study were (1) to gain additional information about how maturity and canopy health influence peg strength, yield, and grade and (2) to address anecdotal claims of differences in peg strength and digging losses among cultivars. Field trials were established in Citra, FL, and Tifton, GA. Two peanut cultivars (“Georgia-06G” and “Tifguard”) were grown under two fungicide programs (full program: every 14-day spraying interval; and reduced program: every 28-day spraying interval), and harvested at three different maturity levels (early, optimum, and late based on an accumulated growing degree day method). The fungicide program had a significant impact on yield only in 2013 at Citra, likely because the canopy structure was decreased because of fungal disease known as leaf spots (causal agents: Cercospora arachidicola and Cercosporidium personatum). The timing of the harvest had a significant impact on yield, grade, peg strength, and digging loss. In addition, yield, grade, peg strength, and digging losses differed between the peanut cultivars. These results show that reduced fungicide program might affect the yield because of the disease severity and that the optimal harvest time should consider the level of the defoliation. Although there was no correlation between peg strength and digging loss, over-maturity can cause more digging losses compared to optimal harvest time. Tifguard had higher digging loss than Georiga-06G. This study provides additional useful information on cultivars to growers.     

Growth and weed suppression ability of common and new cover crops in Germany

Cover crops have a wide-ranging influence on the agroecosystem and create multiple benefits for farmers. A major benefit of cover crops is the suppression of weeds during fall and winter, which can help to reduce soil tillage and herbicide use. However, only a small number of cover crop species are currently grown in Germany. To enlarge this number, four new cover crop species including tartary buckwheat, forage radish, red oat and grain amaranth were tested in comparison with common cover crop species such as white mustard, oilseed radish and phacelia. Emergence, soil coverage, dry matter production and weed suppression ability was assessed for all cover crop species. White mustard emerged faster than all other cover crops and produced the highest amount of shoot dry matter at both locations in southwest Germany twelve weeks after planting (WAP). Oilseed radish was the only cover crop that reduced the weed dry matter in all experiments eight WAP. Phacelia was able to reduce weed density by 77% at Meiereihof twelve WAP. Tartary buckwheat offered the highest soil coverage four WAP, produced the greatest shoot dry matter eight WAP and reduced weed dry matter by more than 96% at Meiereihof and Ihinger Hof twelve WAP. Forage radish produced the highest root dry matter and reduced spring weed density by more than 81% in all experiments. Red oat and grain amaranth emerged slowly, produced less biomass than other cover crops and did not suppress weed growth. The results show that tartary buckwheat and forage radish are well suited as new cover crops in Germany due to their fast growth and good weed suppression ability.