Sugarbeet Root Yield Research Articles

The effect of foliar fertilization with marine calcite in sugar beet

The effect of marine calcite (containing calcium and silicon mainly) foliar fertilization on the sugar beet root yield and technological quality relative to the control (treatment 0) was investigated. Study was conducted in 2011–2012 in the southeastern region of Poland, in Sahryń (50°41'N, 23°46'E). The cultivar of sugar beet was Danuśka KWS. Two treatments of foliar fertilization: (1) treatment (in the stage of 4–6 sugar leaves – 262.0 g Ca/ha, 79.9 g Si/ha, and three weeks later – 524.0 g Ca/ha, 159.8 g Si/ha); and (2) treatment (in the stage of 4–6 sugar leaves – 524.0 gCa/ha, 159.8 g Si/ha, three weeks later – 524.0 g Ca/ha, 159.8 g Si/ha). Calcium and silicon foliar fertilization resulted in increases of: (1) the root yield (average for both treatments about 13.1%; (2) the leaf yield (about 21.0%); (3) the biological sugar yield (about 15.5%), and (4) technological yield of sugar (about 17.7%) compared with the control treatment. At the same time a positive effect on the roots technological quality was found. It was a significant reduction of alpha-amino-nitrogen content and tended to reduce the content of potassium and sodium.

Impact of Tillage, Irrigation Method, and Nitrogen Rate on Sugar Beet Productivity

Strip tillage has gained adoption in recent years with the availability of improved tillage equipment that can prepare a seedbed and place fertilizer in one tillage pass. Nitrogen management, including optimal N rates and placement, is an important concern for sugar beet (Beta vulgaris L.) growers. A 2‐yr study was conducted at Huntley, MT, under flood and sprinkler irrigation to determine if N rates should be adjusted for different tillage and irrigation systems, and to determine if N placement improved sugar beet root yield and quality. Three tillage treatments were compared: conventional tillage with fertilizer broadcast (CT); strip tillage with fertilizer broadcast (ST); and strip tillage with fertilizer banded (SN). Five N rates were randomly applied to plots within each tillage treatment. Check plots were included each year to verify a response to applied N. Averaged over 2 yr, root yield was 3 Mg ha−1 higher under flood irrigation. The CT had higher sugar beet root yield and recoverable sucrose than either ST or SN treatments under flood irrigation. Sugar beets grown under different tillage, and irrigation systems, responded similarly to N fertilizer in both years. Combined results over the 2 yr indicated no significant N × tillage or N × irrigation interactions which implied that fertilizer‐N recommendations do not need to be adjusted for tillage or irrigation system. Moreover, no difference between SN and ST treatments were observed (p = 0.5377) for recoverable sucrose which suggested that banding nutrients with a strip tillage implement did not improve efficiency.

Response of Sugar Beet Yield to Deficit Irrigation under Drip Irrigation System

A field experiment of drip-irrigated sugar beet (Beta vulgaris, L.)was conducted at the research field of the Nubaria Agricultural Research Station, Egypt at 30° 54' 21'' N, 29° 52' 15'' E and 11.0 m altitude above mean sea level during 2011/2012 growing season.The aim of the present study was to evaluate the impact of deficit irrigation on sugar beet productivity, and quantitative and qualitative characteristics of sugar beet root yield under drip irrigation. The sugar beet (Beta vulgaris, L) variety Gloria (polygerm) was planted on 13 October 2011. Sugar beet plants were thinned to one plant at distance of about 0.3 m on the rows at the 4th week after planting. After emergence, the plots were irrigated by the drip irrigation method.The present study consisted of 5 treatments. The irrigation treatments were based on replenishment of soil water depletion according to reference evapotranspiration (ET0). The irrigation treatments were: Irrigation at 40, 60, 80, 100 and 120% of ET0. Sugar beet vegetative growth, sugar beet yield and yield components, and juice quality and impurities content were determined. The results clearly indicated a significant effect of different irrigation regimes on all sugar beet growth characters except leaf area per plant and foliage water content as compared with control (100% of ET0). The results alsoclearly indicated a significant effect of irrigation regimes on sugar beet yield and yield components. Irrigation at 40% of ET0 gave a highest value of root length (32.7cm) and root diameter (13.0 cm), but 60 % of ET0 gave the highest values of average root fresh weight (1500 g/plant) and root gross yield (100.0 ton/ha). The highest value of root/top ratio (1.31) was attained at irrigation with 120% of ET0. The percent increase of root gross yield of sugar beet at 60% of ET0 was account as 49.99%, for gross sugar yield was 45.66% and for white sugar yield was 44.16% over the common treatment (100% of ET0). The different irrigation regimes significantly affected the juice quality and impurities contents of sugar beet. Irrigation at 40 and 60% of ET0 gave the highest value of TSS (total soluble solids), 23.0%, white sugar yield (13.71 ton/ha), gross sugar yield (16.97 ton/ha) and loss sugar yield (3.26 ton/ha) were attained at 60% of ET0. The highest values of polarity or sucrose content (17.76 %), effective polarimetric assay of sugar (15.46%),thick purity juice, TPJ (90.66%), white sugar content (14.94%) and juice purity (84.13%) were attained at 60% of ET0. The increase in sugar yield was due to both increase in sugar content and root yield in which sugar yield was adversely affected by water deficit. Increasing the impurities in the root of stressed plants decreased extraction of white sugar. So, deficit irrigation improved sugar beet quality by reducing these impurities. The findings in this study strongly recommend that up to 60% deficit irrigation of sugar beet would be advantage if the farmers target is to maximize root and white sugar yield. But if the target is to put more area into production under limited water supply, irrigation at 40% of reference evapotranspiration in sugar beet may be feasible.

Impact of Nitrogen and Weeds on Glyphosate-Resistant Sugarbeet Yield and Quality

Field experiments were conducted in 2010 and 2011 at two locations in Michigan to determine the effects of nitrogen and weed removal on glyphosate-resistant sugarbeet yield and quality. Nitrogen rates were 0, 67, 100, 134, and 67 : 67 kg N ha−1, and weeds were removed when they were < 2, 8, 15, and 30 cm tall. At the beginning of the growing season, weeds responded to N sooner than sugarbeet. Nitrogen assimilation by weeds was three times greater than sugarbeet at 0, 67, 100, and 134 kg N ha−1 and four times greater than sugarbeet with the split application of N (67 : 67 kg N ha−1) averaged over the weed removal timings. Higher N rates increased N sufficiency index values and sugarbeet canopy closure; weeds 30 cm tall had lower N sufficiency index values and a smaller sugarbeet canopy. The effect of N on root yields varied, but the highest N rates (134 kg N ha−1 or 67 : 67 kg N ha−1) were among the highest sugarbeet yields at all locations. Highest yields were achieved when weeds were controlled before reaching 2 cm tall at three of the four site-years. Delaying weed control until weeds were 8 or 15 cm tall reduced yield by 15%, whereas 30-cm-tall weeds reduced yield up to 21%. Recoverable white sucrose ha−1 (RWSH) also was reduced by 8 to 16% if weeds were 8 cm tall. These results indicate that weeds are highly competitive with sugarbeet and can assimilate large quantities of N early in the growing season, especially at larger growth stages. However, it appears that sugarbeets were able to scavenge sufficient N at the N rates used in this study to overcome N removal effects from larger weeds, resulting in no interaction between N rate and weed removal timing for sugarbeet root yield, quality, or RWSH.

Wpływ łącznego stosowania biostymulatora Aminoplant z herbicydami na wielkość i jakość plonu buraka cukrowego

Experiments were conducted at the Experimental Field Station of theInstituteofPlant Protection– National Research Institute in Winna Góra, in 2011–2012. The aim of the study was to assess the effects of biostimulator Aminoplant on the development and yield of sugar beet and the activity of herbicides. The primary protection from weed control was treatments with a mixture of two herbicides Betanal EC 274 Elite with Safari 50 WG in three terms, in the split dose. Aminoplant applied two or three times together with herbicides and three times in a single operation. The application of Aminoplant increased the yield of sugar beet roots, but had no significant effect on the quality parameters of sugar beet roots like sugar, sodium, nitrogen and potassium content. The addition of biostimulator Aminoplant to herbicides had no negative effect on treatment efficacy and phytotoxicity against sugar beet plants. Aminoplant application date and number of treatments should be adjusted to the possibilities of chemical weed control and the appropriate growth stage of sugar beet. Badania przeprowadzono w latach 2011–2012 na terenie Polowej Stacji Doświadczalnej Instytutu Ochrony Roślin – Państwowego Instytutu Badawczego w Winnej Górze. Celem badań była ocena efektów działania nawozu organicznego o cechach biostymulatora Aminoplant na rozwój i plonowanie buraka cukrowego w zabiegach łącznych z herbicydami. Podstawową ochronę przed zachwaszczeniem stanowiły zabiegi z użyciem mieszaniny dwóch herbicydów Betanal Elite 274 EC z Safari 50 WG w trzech terminach, w ramach dawek dzielonych. Środek Aminoplant użyto dwu- lub trzykrotnie łącznie z herbicydami oraz trzykrotnie w zabiegu pojedynczym. Stosowanie biostymulatora Aminoplant wpłynęło na zwiększenie wielkości plonu korzeni buraka cukrowego, natomiast nie miało istotnego wpływu na parametry jakościowe korzeni buraka cukrowego, takie jak: cukier, azot, sód i potas. Dodatek biostymulatora Aminoplant nie miał wpływu na efektywność chwastobójczą i fitotoksyczność herbicydów w stosunku do roślin buraka cukrowego. Termin stosowania środka Aminoplant i liczbę zabiegów należy dostosować do możliwości chemicznej ochrony przed chwastami i odpowiedniej fazy rozwojowej buraka cukrowego.

Sugar beet yield as affected by seed priming and weed control

Laboratory and field experiments were conducted to determine the influence of different priming techniques on the germination characteristics and competition of weeds in sugar beet in 2008–2009. Three priming times and four priming methods were used in a laboratory study, and four priming treatments and four redroot pigweed densities (0, 4, 8 and 12 plants m−2) were used in a field study. Sugar beet seeds were treated with polyethylene glycol (PEG 8000), NaCl (1.5 N) and HCl (0.1 N) for 2, 4 and 6 h. Seed characteristics were significantly affected by HCl (0.1 N) treatment for 6 h. In this treatment, the germination percentage was 25 and 9% higher than control and NaCl (1.5 N) treatments after a similar time. An intermediate and low effect has been shown with NaCl (1.5 N) and PEG 8000 seed priming, respectively. Sugar beet root yield was reduced by 13, 54 and 89% compared with control treatment (without weed) at redroot pigweed densities of 4, 8 and 12 plants m−2, respectively. Sugar beet seeds primed with HCl (0.1 N) for 6 h gave a higher root yield than unprimed seeeds and the other primed seeds treatments. Overall, the results showed that weed control can significantly increase sugar beet yield and the seed priming technique can be used for weed control.

Effect of intercropping of maize, bean, cabbage and toxicants on the population levels of some insect pests and associated predators in sugar beet plantations

Experiments were carried out at El-Riad district, Kafr El-Sheikh Governorate in two successive growing seasons (2009/10 and 2010/11) to study the effect of intercropping of faba bean, maize and cabbage with sugar beet on the population density of Empoasca spp. (nymphs and adults), Aphis spp. (nymphs and adults), Bemisia tabaci (adults), Pegomyia mixta (eggs and larvae), Cassida vittata (larvae, pupae and adults) and predators in sugar beet plantations compared with the non-intercropped plants and the resulting yield. The toxicity of certain compounds: fenitrothion, super misrona, sour orange oil, acidless orange oil, and Bermectine in reducing the population density of P. mixta and C. vittata larvae infesting sugar beet was evaluated. The rate of infestation was higher in the sole sugar beet plants than in those intercropped with faba bean, maize and cabbage plants which caused reduction of sucking pests and P. mixta eggs in the two seasons. The intercropping of faba bean plants led to higher infestation rate of P. mixta larvae in the two seasons and C. vittata (larvae, pupae and adults) in the first season. The intercropping with maize led to a higher population density of Chrysoperla carnea, Paederus alfierii and Scymnus spp. in the two seasons. Low population density of true spiders was observed in sole sugar beet (control) when compared with faba bean, maize and cabbage plants intercropped in the two seasons. Concerning the obtained root yield, the intercropping with maize and cabbage plants reduced the resultant yield of sugar beet roots in the two seasons. Bermectine and fenitrothion were the most effective toxicants followed by super misrona and then, sour orange that induced the lowest reduction in P. mixta larvae. Also, fenitrothion and Bermectine were the most potent compounds in reducing the population density of C. vittata larvae followed by super misrona and then, plant oil extracts. Concerning the side effects of these compounds on predators, sour orange oil and acidless orange oil had slight effects, whereas Bermectine and super misrona caused a moderate effect against predators. However, fenitrothion was the most highest toxic compound against predators.

Interference of Redstem Filaree (Erodium cicutarium) in Sugarbeet

Redstem filaree is a troublesome weed for sugarbeet growers in northern Wyoming and southern Montana. Field studies were conducted in Powell, WY, in 2006 and 2008 to determine the influence of season-long interference of various redstem filaree densities and the duration of interference on sugarbeet. Root and sucrose yield decreased with increasing redstem filaree density. The rectangular hyperbola model with the asymptote (A) bounded at 100% maximum yield reduction characterized the relationship between redstem filaree density and sugarbeet yield reduction. The estimated parameterI(percent yield reduction per unit weed density as density approaches zero) was 5% for root and sucrose yield reduction. Sugarbeet root yield decreased as the duration of redstem filaree interference increased. The critical timing of redstem filaree removal to avoid 5 and 10% root yield reduction was estimated to be 25 and 32 d after sugarbeet emergence, respectively. Redstem filaree interference did not affect the sucrose content percentage. These results demonstrate that redstem filaree is competitive with sugarbeet and should be managed appropriately to reduce negative effects on yield.

Late-Season Weed Control in Glyphosate-Resistant Sugarbeet

Field trials were conducted from 2006 through 2008 to determine the influence of ethofumesate applied at planting followed by dimethenamid-p ors-metolachlor applied to emerged sugarbeet for late-season weed control in glyphosate-resistant sugarbeet. The entire plot area was kept weed-free until mid-June by applying glyphosate at the four- and eight-true-leaf sugarbeet growth stages. Glyphosate was not applied from mid-June until late-July to allow weed growth as a measure of the residual benefit from ethofumesate, dimethenamid-p, ands-metolachlor applied earlier in the growing season. Dimethenamid-p was not as effective ass-metolachlor in reducing weed density in mid-July. Late-season weed suppression from boths-metolachlor and dimethenamid-p benefitted from ethofumesate applied at planting. Dimethenamid-p applied when sugarbeet reached the six-true-leaf growth stage reduced weed density and sugarbeet injury more than earlier applications. The lowest weed density in mid-July was achieved whens-metolachlor was applied at the six- to eight-true-leaf sugarbeet growth stage compared to earlier growth stages. A planting time application of ethofumesate followed by two glyphosate applications pluss-metolachlor at the eight-true-leaf sugarbeet growth stage provided 89% more weed control in mid-July than glyphosate alone. Suppressing late-season weed development increased sugarbeet root yield 15% compared with areas not receiving ethofumesate ands-metolachlor.

Effect of Time and Concentration of Boron Foliar Application on Yield and Quality of Sugar Beet

A field experiment was carried out at the Research Center of Barkat-e-Jovein, Jovein agro-industries, Northeastern Iran, during 2008 to evaluate the effect of concentration and time of boron foliar application on root yield and quality of sugar beet (Beta vulgaris). Treatments consisted of 3 application times (30, 45 and 60 DAP) and 4 application rates (spraying with concentrations of 0, 4, 8 and 12‰ corresponding with 0, 0.35, 0.70 and 1.22 kg B ha as water-soluble B (Boric acid)). Results revealed that application time had no considerable 1 effect on sucrose concentration, root yield, k , Na , molasses sugar, nor on reducing nitrogen. Boron ++ application increased root yield and sucrose concentration by 12.12% and 26.35%, respectively, decreasing k , + Na , -amino-N and molasses sugar compared with those of the control. In this study, no significant differences +

EFFECT OF CHICKEN MANURE AND GYPSUM ON SUGAR BEET (Beta vulgaris, VAR. SACCHARIFORA, L.) UNDER SALINE CONDITION

A plastic bags trial was conducted at the Agric. Experimental Station of Mansoura University using sandy soil to study the effect of chicken manure levels (0, 5, 10, 15 and 20 tons/fed) and gypsum rates (0, 2.5, 5, 7.5 and 10 tons/fed ) on nutrients uptake and yield of sugar beet plant irrigated with saline water. The experiment was conducted in a spilt plot design with three replicates during the two successive seasons 2007-2008 and 2008-2009 The Obtained results indicated that the yield of sugar beet roots increased significantly by adding chicken manure over the control. The highest level (20 tons/fed) gave 289.9 and 327.1 g/plant during first and second season, respectively. Also, the highest gypsum rate increased significantly root yield to be 307.15 and 341.77 g/plant during first and second season, respectively. Also, elements uptake such as N,P,K and Na were increased significantly over control due to supplying with either chicken manure or gypsum to a sandy soil. The same trend was found with the interaction effect of both treatments. Also, It could be recognized that chicken manure gave relatively higher increase in some characters than gypsum treatments. Data also revealed that root quality parameters such as SC%, TSS%, purity and sugar yield significantly increased with chicken manure over the control by 26.67% and 27.86 for TSS%, 18.96% and 18.74% for SC% and 77.39 and 79.98 g/plant for sugar yield in the 1st and 2nd season, respectively. Whereas, purity as a quality parameter significantly decreased with increasing chicken manure and gypsum treatments due to uneventually increasing for Sc% and TSS% which was not in a harmony which reflecting in decreasing purity. Generally, the interaction between chicken manure and gypsum revealed that the high rate of both chicken manure and gypsum treatments gave the highest root yield, elements uptake (N,P,K and Na) and sugar yield.

Lanceleaf Sage (Salvia reflexa) Interference in Sugarbeet

Field studies were conducted in Powell, WY, in 2006 and 2007 to determine the influence of season-long interference of various lanceleaf sage densities and durations of interference on sugarbeet. The rectangular hyperbola model with the asymptote (A) constrained to 100% maximum yield loss characterized the relationship between lanceleaf sage density and sugarbeet yield loss. The estimated parameterI(yield loss per unit weed density as density approaches zero) was 3% for both root and sucrose yield loss. Increasing duration of lanceleaf sage interference had a negative effect on sugarbeet root yield. The critical timing of weed removal to avoid 5 and 10% root yield loss was 37 and 52 d after sugarbeet emergence, respectively. Lanceleaf sage interference did not affect percentage of sucrose content. These results indicate that lanceleaf sage is not as competitive as other weeds but that appropriate control measures should be undertaken to minimize sugarbeet yield loss from interference.

Weed Management in Wide- and Narrow-Row Glyphosate-Resistant Sugarbeet

Planting glyphosate-resistant sugarbeet in narrow rows could improve weed control with fewer herbicide applications and cultivations. Field studies were conducted in 2007 and 2008 at multiple locations in Michigan to compare weed management and sugarbeet yield and quality in glyphosate-resistant sugarbeet planted in 38-, 51-, and 76-cm rows. At all locations, weed densities and biomass were less after glyphosate treatments than after conventional herbicide treatments. Weed densities and biomass also were less in 38- and 51-cm rows compared with 76-cm rows following a single glyphosate application when weeds were 10 cm tall. Averaged over row width, sugarbeet treated with glyphosate when weeds first reached 2 cm in height and again as needed thereafter yielded similarly to sugarbeet treated when weeds were 5 to 10 cm tall. However, root yields were reduced when glyphosate application was delayed until weeds averaged 15 cm in height. Sugarbeet root and sugar yields were greater from 38- and 51-cm row widths than from the 76-cm row widths, averaged over all herbicide treatments. Regardless of row width, initial glyphosate applications should be made before weeds reach 10 cm in height to maximize yield and minimize weed competition with sugarbeet.

Population density and soil seed bank of weed beet as influenced by crop sequence and soil tillage

Dynamics of population density and soil seed bank of weed beet was studied in a 5 year crop rotation consisting of spring barley, and sugar beet. Beside the crop rotation experiment, the seeds of weed beet were studied for their dormancy and viability in soil seed bank over the period of four years. The obtained data indicates that weed beet was able to produce seeds only in sugar beet, but not in barley. In sugar beet, its reproductive potential allows weed beet to restore and increase the soil seed bank of glomerules rapidly. Common infestation of sugar beet is able to persist over more than the 2-year period between repeated introductions of sugar beet in crop rotation. The experiment has also proven the negative effect of weed beet presence on sugar beet yield. The sugar beet root yield decreased of 0.4 t/ha with every 1000 weed beet plants per hectare. The yearly loss of viable seeds was about 75%. The number of surviving seeds decreased exponentially in time. Less than 2% of seeds remained viable after three years in the soil. Seasonal fluctuations of seed dormancy were observed. Seeds were dormant in autumn, lost dormancy in winter and recovered it in late summer.

Effect of different drip irrigation regimes on sugar beet (Beta vulgaris L.) yield, quality and water use efficiency in Middle Anatolian, Turkey

Agricultural production has forced researchers to focus on increasing water use efficiency by improving either new drought-tolerant plant varieties or water management for arid and semi-arid areas under water shortage conditions. A field study was conducted to determine effects of seasonal deficit irrigation on plant root yield, quality and water use efficiency (WUE) of sugar beet for a 2-year period in the semi-arid region. Irrigations were applied when approximately 50–55% of the usable soil moisture was consumed in the effective rooting depth at the full irrigation (FI) treatment. In deficit irrigation treatments, irrigations were applied at the rates of 75, 50 and 25% of full irrigation treatment on the same day. Irrigation water was applied by a drip irrigation system. Increasing water deficits resulted in a relatively lower root and white sugar yields. The linear relationship between evapotranspiration and root yield was obtained. Similarly, WUE was the highest in DI25 irrigation conditions and the lowest in full irrigation conditions. According to the averaged values of 2 years, yield response factor (ky) was 0.93 for sugar beet. Sugar beet root quality parameters were influenced by drip irrigation levels in both years. The results revealed that irrigation of sugar beet with drip irrigation method at 75% level (DI25) had significant benefits in terms of saved irrigation water and large WUE, indicating a definitive advantage of deficit irrigation under limited water supply conditions. In an economic viewpoint, 25% saving of irrigation water (DI25) caused 6.1% reduction in the net income.

Wild Buckwheat (Polygonum convolvulus) Interference in Sugarbeet

Field studies were conducted in Powell, WY in 2006 and 2007 to determine the influence of season-long interference of various wild buckwheat densities and duration of interference on sugarbeet. Percent sucrose content was not affected by wild buckwheat interference. Root and sucrose yield loss per hectare increased as wild buckwheat density increased. The estimated percent yield loss as wild buckwheat density approaches infinity was 64 and 61% for root and sucrose yield loss, respectively. The estimated percent yield loss per unit weed density at low weed densities was 6% for both root and sucrose yield loss. Greater durations of wild buckwheat interference had a negative effect on sugarbeet root yield. The critical timing of weed removal (CTWR) to avoid 5 and 10% root yield loss was 32 and 48 d after sugarbeet emergence (DAE), respectively. These results show that wild buckwheat is competitive with sugarbeet and should be managed appropriately to forestall any negative effects on sugarbeet root and sucrose yield.

Effect of Azotobacter chroococcum on sugar beet and microbial activity of rhizosphere

In sugar beet production, one of the most important factors that affect the yield, apart from genetic properties, is the use of mineral fertilizers. Considerate amounts of mineral fertilizers are used in sugar beet production. However, if agroecological conditions are not optimum, mineral fertilizers cannot be completely absorbed, which may lead to soil contamination. Therefore, research has been focusing on ways of using atmospheric nitrogen by means of nitrogen-fixing bacteria. Numerous researches have proved that one part of mineral fertilizers can be replaced by biological nitrogen. The aim of this research was to determine the effect of genotype, azotobacter and the amount of mineral fertilizers on the root yield of sugar beet and on the microbiological activity of the sugar beet rhizospheric soil. Three hybrids of sugar beet were used during the two years of the research. The seed of the hybrids was inoculated with three strains of azotobacter. Various amounts of NPK were used (0;30;60;90 kg/ha). At the end of the vegetation period, the following were determined: root yield, total number of bacteria, number of azotobacter, oligotrophic bacteria, ammonifiers, fungi, and actinomycetes in soil. Dehydrogenase activity was measured. The results were processed statistically (analysis of variance for factorial trials) and the effect of the factors was determined upon the expected mean square values. The yield was mainly affected by the amount of mineral fertilizers. However, the effect of mineral fertilizers was different with different inoculation treatments. The effect of the examined factors was dependant upon genotype, amount of mineral fertilizers, inoculation and the year of trials. The interaction between genotype, mineral fertilizers, inoculation and the year of trials was the factor that had the greatest effect on the number of almost all the examined soil microorganisms.

Venice Mallow (Hibiscus trionum) Interference in Sugarbeet

Field studies were conducted in Powell, WY, in 2006 and 2007 to determine the influence of season-long interference of various Venice mallow densities and duration of interference on sugarbeet. Sucrose concentration was not affected by Venice mallow interference. The effect of Venice mallow density on sugarbeet root and sucrose yield loss was described by the rectangular hyperbola model. Root and sucrose yield loss increased as Venice mallow density increased. The estimated asymptote,A(percent yield loss as density approaches infinity) was 61% for both root and sucrose yield loss, and the estimated parameter,I(percent yield loss per unit weed density as density approaches zero) was 6% for both root and sucrose yield loss. Sugarbeet root yield decreased as the duration of Venice mallow interference increased. The critical timing of weed removal to avoid 5 and 10% root yield loss was 30 and 43 d after sugarbeet emergence, respectively. Results show that Venice mallow is competitive with sugarbeet implying that it should be managed appropriately to reduce negative effects on yield and prevent seed bank replenishment and re-infestation in subsequent years.

Evaluation of the influence of irrigation methods and water quality on sugar beet yield and water use efficiency

Abstract Rapid urbanization and industrialization have increased the pressure on limited existing fresh water to meet the growing needs for food production. Two immediate responses to this challenge are the efficient use of irrigation technology and the use of alternative sources of water. Drip irrigation methods may play an important role in efficient use of water but there is still limited information on their use on sugar beet crops in arid countries such as Iran. An experiment was conducted to evaluate the effects of irrigation method and water quality on sugar beet yield, percentage of sugar content and irrigation water use efficiency (IWUE). The irrigation methods investigated were subsurface drip, surface drip and furrow irrigation. The two waters used were treated municipal effluent (EC = 1.52 dS m−1) and fresh water (EC = 0.509 dS m−1). The experiments used a split plot design and were undertaken over two consecutive growing seasons in Southern Iran. Statistical testing indicated that the irrigation method and water quality had a significant effect (at the 1% level) on sugar beet root yield, sugar yield, and IWUE. The highest root yield (79.7 Mg ha−1) was obtained using surface drip irrigation and effluent and the lowest root yield (41.4 Mg ha−1) was obtained using furrow irrigation and fresh water. The highest IWUE in root yield production (9 kg m−3) was obtained using surface drip irrigation with effluent and the lowest value (3.8 kg m−3) was obtained using furrow irrigation with fresh water. The highest IWUE of 1.26 kg m−3 for sugar was obtained using surface drip irrigation. The corresponding efficiency using effluent was 1.14 kg m−3. Irrigation with effluent led to an increase in the net sugar yield due to an increase in the sugar beet root yield. However, there was a slight reduction in the percentage sugar content in the plants. This study also showed that soil water and root depth monitoring can be used in irrigation scheduling to avoid water stress. Such monitoring techniques can also save considerable volumes of irrigation water and can increase yield.

Weed Management in Glyphosate- and Glufosinate-Resistant Sugar Beet

Field experiments were conducted to determine the critical period of weed interference in glyphosate- and glufosinate-resistant sugar beet, and to determine if PRE herbicides increased weed control or sugar beet root yield when glufosinate, glyphosate, or conventional POST herbicides were applied. Glyphosate- and glufosinate-resistant sugar beet root yields were reduced by up to 66 and 67%, respectively, when weeds remained all season in the weedy control treatment compared with yields when weed removal occurred as soon as the weeds were 2.5 cm tall, approximately 2 to 3 wk after planting (WAP). A critical period of weed interference did not occur in this research. The critical time of weed removal was approximately 8 WAP in 1998 and beyond 11 WAP in 1999. Weeds averaged 20 cm in height at 8 WAP and weed densities were greater in 1998 compared with 1999. The critical weed-free period for glyphosate- and glufosinate-resistant sugar beet was 4.5 to 5 WAP in 1998. In 1999, the critical weed-free period at the Michigan Sugar location was 1.5 WAP in glyphosate-resistant sugar beet, and 6.5 WAP in glufosinate-resistant sugar beet for the Michigan Sugar site. Glyphosate or glufosinate POST provided better weed control and resulted in greater sugar beet root yield compared with conventional POST herbicides when data were combined over PRE herbicide treatments. PRE herbicides improved the control of common lambsquarters andAmaranthusspecies in some of the site-years when data were combined over POST treatments, but sugar beet yield did not increase. Our research suggests that PRE herbicides will not be necessary in glyphosate- or glufosinate-resistant sugar beet. To avoid sugar beet yield loss, multiple POST applications of glyphosate or glufosinate will be needed until 6 to 9 WAP to prohibit yield loss from weeds emerging after the last POST application.