76-cm Row Spacing Research Articles

Remediation of Cd contaminated paddy fields by intercropping of the high- and low- Cd-accumulating rice cultivars

Intercropping cadmium (Cd) hyperaccumulators with crops have been widely applied in the remediation of contaminated farmland soils. However, most studies were done on drylands since the majority of the hyperaccumulators are susceptible to the aquatic environment, making the remediation of Cd-contaminated paddy fields particularly difficult. Our study attempts to address the issue by intercropping the high-Cd-accumulating (henceforth, “high-Cd”) rice cultivars with the low-Cd-accumulating (henceforth, “low-Cd”) ones, and to study the Cd removal, uptake and translocation during the remediation process. The results indicated that intercropping mode with 20-cm row spacing (intercropping-20 treatment) performed better than the that with 30-cm row spacing (intercropping-30 treatment), while intercropping had stronger impact on late rice compared to early rice. In general, the physiological condition of rice was stable under the intercropping-20 treatment, suggesting the growth of rice was not impeded. For late rice, as the intercropping-20 treatment can significantly reduce soil pH and increase the diethylenetriaminepentaacetic acid extracted Cd (DTPA-extracted Cd) from the rhizosphere soil, Cd accumulated more in the tissues of the high-Cd rice cultivars (H2), and its dry biomass increased. As a result, a drastic improvement in the total Cd removal rate by 38.55 % was noticed. Therefore, the reduction of total Cd concentration in 0–20 cm profile caused by removal, thus it could provide safer soil environment for the growth of low Cd-rice cultivars (L2), leading to a significant drop in the root Cd concentration and safer production of L2. Interestingly, intercropping had no effect on the yield per plant of low-Cd rice cultivars. For early rice, intercropping-20 treatment exerted trivial effects to all aspects. The intercropping-30 treatment has poor representativeness of all indicators because of the large intercropping distance. Our results demonstrate that intercropping of the high-Cd and the low-Cd rice cultivars is a potential mode for Cd remediation in paddy fields.

Effect of Organic and Liquid Manures on Yield, Yield Attributes and Economic of Urdbean

A field experiment was carried out in 2020 kharif season, on loamy sand soil at the S.K.N. College of Agriculture's Agronomy Farm in Jobner (Rajasthan). It included two foliar sprays of each of four liquid manures (control, 100% RDP panchgavya @ 5%, 100% RDP vermiwash @ 10%, and 100% RDP cow urine @ 5%), totaling sixteen treatment combinations. It included four treatments of organic manures (control, 100% RDP through FYM, through vermicompost, and through poultry manure) and two foliar sprays of each of four liquid manures. Three replications of the experiment were set up using a Randomized Block Design. 'Krishna' variety of urdbean was sown as on July 13, 2020, a test crop with a 30-cm row spacing. The results showed that two foliar sprays of 5% panchgavya were the most effective liquid manure treatment in raising the maximum seed production (942 kg/ha), straw yield (2,121 kg/ha), and biological yield (3,063 kg/ha) of urdbean. The highest levels of nitrogen, phosphorous, and potassium were found in seed and straw under this liquid manure treatment, which was comparable to two foliar sprays of 10% vermiwash. However, applying 100% RDP through FYM was the most lucrative strategy, for obtaining higher yield, net returns of '36,314/ha and a B:C ratio of 2.68. Foliar spraying with 5% panchgavya also generated an extra 36,798/ha in net returns over the control, which had the highest B:C ratio of 2.37.

Double-Double Row Planting Mode at Deficit Irrigation Regime Increases Winter Wheat Yield and Water Use Efficiency in North China Plain

Low water availability coupled with poor planting method has posed a great challenge to winter wheat (Triticum aestivum L.) productivity. To improve productivity and water use efficiency (WUE) under deficit irrigation, an effective water-saving technology that is characterized by three planting modes has been developed (uniform with 30-cm row spacing (U), double-double row spacing of 5 cm (DD), and furrow-ridge row spacing of alternated 20 cm and 40 cm (F)) combined with three irrigation regimes (50 mm water each at growth stage 34 (GS34) and GS48 (W1), and 100 mm water at GS48 (W2), or 100 mm each water at GS34 and GS48 (W3)). Results showed that DD increased yield by 9.7% and WUE by 12.6% due to higher soil water status and less soil water depletion and evapotranspiration compared with U. Although the soil water status, soil water depletion, evapotranspiration, and yield increased with increasing irrigation amount, more soil water depletion and evapotranspiration resulted in low WUE. The deficit irrigation was beneficial for improving WUE as W1 had significantly increased yield by 5.4% and WUE by 7.1% compared with W2. Yield and evapotranspiration showed a quadratic dynamic equation indicating that yield increased with increasing evapotranspiration. Considering WUE and relatively higher yield under deficit water, W1 combined with DD is suggested to be a good management strategy to be applied in winter wheat of water-scarce regions.

Influence of seed priming techniques on grain yield and economic returns of bread wheat planted at different spacings

A 3-year study evaluated the effect of different seed-priming techniques on the performance of two bread wheat (Triticum aestivum L.) cultivars, Seher-2006 and Shafaq-2006, planted in rows spaced at 22.5 or 30 cm. Three seed priming techniques—on-farm priming, hydropriming, and osmopriming (using CaCl2)—and an untreated control (dry seeds) were included in the study. Seed priming resulted in earlier and more uniform crop emergence and improved allometric and yield-related traits compared with untreated seeds. Hydropriming and osmopriming significantly improved the allometric traits of Seher-2006 planted at 22.5-cm row spacing and Shafaq-2006 planted at 30-cm row spacing each year. The combination of osmopriming and 30-cm row spacing produced the highest number of productive tillers, number of grains per spike and 1000-grain weight across all experimental years. The highest grain yield and harvest index were recorded for osmopriming and 22.5-cm row spacing each year. Shafaq-2006 produced higher biological yield, whereas Seher-2006 produced the higher grain yield and harvest index. Osmoprimed seeds planted at 22.5-cm row spacing recorded the highest economic returns and benefit:cost ratios in both cultivars. In conclusion, planting osmoprimed seeds of wheat in 22.5-cm spaced rows could be effectively used to increase productivity and economic returns.

Investigation of yield, yield components and nutrient contents of wild rocket (Diplotaxis tenuifolia (L.) DC.)

Wild rocket (Diplotaxis tenuifolia (L.) DC.), a member of the Brassicaceae family, is vital in natural areas and soil protections as well as in human and animal nutrition. The study was conducted to determine the appropriate row spacing of Turkey’s native plant wild rocket in Konya conditions. This study was conducted in 2015; observations and measurements were carried out in the second (i.e., 2016) and third (i.e., 2017) years. In this study, fodder yield and its components consisted of plant height, canopy diameter, number of branches, fresh and dry fodder yield per plant, and dry fodder yield per hectare and seed yield and its components consisted of number of pods per branch, number of pods per plant, 1000 grains weight, seed yield per plant, and seed yield per hectare were examined. Macro and micronutrient contents of the plant were also analyzed in 2016. The results show that seed yield values such as seed yield (i.e., 76.2 kg ha−1) and 1000 grains weight (i.e., 1.00 g) were higher in 2016. However, in 2017, while seed yield was lower, plant height (i.e., 92.78 cm), canopy diameter (i.e., 85.67 cm), and fodder yield (i.e., 20339.5 kg ha−1) were higher. In nutrient contents (especially Ca, K, and Fe), 20- and 30-cm row spacings were determined as significant. Furthermore, the yield values related to dry fodder and seed yields are higher with 20- and 30-cm row spacings. This study indicated that 20- and 30-cm row spacings are recommended row spacing for wild rocket culture.

Effects of row-spacing and stubble height on soil water content and water use by canola and wheat in the dry prairie region of Canada

Studies were conducted to examine the effects of row spacing and stubble height on surface soil water content, water use, yield, and water use efficiency of canola and wheat in the drier regions of the Canadian prairies. For this purpose, randomized complete block design trials were implemented separately in canola and wheat fields at Central Butte and Swift Current in the Brown soil zone of southwestern Saskatchewan. At each experimental site, two factors and two levels for each factor, i.e., 30- and 60-cm row spacing and 15- and 30-cm stubble heights, were included. Wider row spacing and taller stubble generally increased soil water content for the surface 0–30cm soil depth, and taller stubble often had greater spatial variability of surface soil water content at both locations. Row spacing or stubble height had minimal effect on water use for both crops at both locations over the two years (2012 and 2013). Yield and water use efficiency of 30-cm row spacing were 1.3–1.6 (Central Butte) and 1.0–1.2 (Swift Current) times greater than those of 60-cm row spacing. Stubble height had little effects on yield and water use efficiency. There were no interactions of row spacing and stubble height on water use, yield, and water use efficiency for either crop. Overall, 30-cm row spacing and 30-cm stubble tended to increase surface soil water content, yield, and water use efficiency for most crop type, year, and site combinations.

Yield and nutritive value response to row spacing and cultivar in forage rice

Although the forage rice (Oryza sativa L.) cultivar ‘Ruriaoba’ has very high dry matter (DM) yield, it readily lodges after heading because of its high plant height. As a result, seed production and conventional cultivation of ‘Ruriaoba’ are very difficult. To improve this situation, we examined the effects of cultivar (‘Ruriaoba’ or ‘Tachiaoba’) and row spacing (30 [30–30–30–30] cm, 45 [30–30–30–45] cm, or 60 [30–30–30–60] cm) on the yield and nutritive value of forage rice. The lodging score of ‘Tachiaoba’ did not differ among row spacings but that of ‘Ruriaoba’ decreased with increasing row spacing. ‘Ruriaoba’ had lower grain yield than ‘Tachiaoba’. Among its components, ‘Ruriaoba’ had fewer spikelets per m2, fewer spikelets per panicle and lower 1000-grain weight than ‘Tachiaoba’. ‘Ruriaoba’ had fewer grains per m2 than ‘Tachiaoba’. Grain yield and its components did not differ among row spacings, nor did the number of grains per m2. Thus, ‘Ruriaoba’ planted at 60-cm row spacing may not decrease the grain yield and number of grains without lodging. This type of low-density planting of ‘Ruriaoba’ may be useful for seed production. At heading and yellow ripe stages, ‘Ruriaoba’ had higher DM yield than ‘Tachiaoba’ because ‘Ruriaoba’ had higher number of panicles than ‘Tachiaoba’. Furthermore, ‘Ruriaoba’ had higher total digestible nutrients (TDN) yield than ‘Tachiaoba’. At heading, DM yield decreased with increasing row spacing because the number of panicles decreased with increasing row spacing. Total digestible nutrients yield was lower at 45- and 60-cm row spacings than at 30-cm row spacing. However, at heading and yellow ripe, ‘Ruriaoba’ planted at 60-cm row spacing had DM and TDN yields similar to those of ‘Tachiaoba’ planted at 30-cm row spacing. Such low-density planting of ‘Ruriaoba’ may be an option for forage rice production.

Effects of Mixture Ratio and Row Spacing in Hungarian Vetch (Vicia pannonica Crantz.) and Annual Ryegrass (Lolium multiflorum Lam.) Intercropping Sys

This study was conducted at the Middle Kizilirmak basin of Turkey (40°20′N, 33°58′E, elevation 550 m), during the 2011–2012 and 2012–2013 growing seasons, to determine the effects of different mixture ratios (sole Hungarian vetch (HV), annual ryegrass (AR); 80%HV+20%AR, 60%HV+40%AR, 40%HV+60%AR, and 20%HV+80%AR) and row spacings (20, 30, and 40 cm) on the forage yield and quality of the HV and AR intercropping system. The experiment was planned in a randomized complete block design, where a split-plot arrangement of mixture ratios was considered as the main plot with the row spacings considered as subplots. According to the mean of 2 years, the different mixture ratios and row spacings had a statistically significant effect on all of the properties. At the end of the research, among the different mixture ratios and row spacing interactions, the highest green herbage yield (33.4 t ha–1), hay yield (7.5 t ha–1), lowest neutral detergent fiber (52.2%), and crude ash (7.8%) rates were obtained from the 60%HV+40%AR mixture and 30-cm row spacing interaction. The highest crude protein (CP) rate (17%), CP yield (1156 kg ha–1) and ADF (39.5%) ratios were obtained from the 80%HV+20%AR mixture and 30-cm row spacing interaction. The highest RFV value (107) was obtained from the 80%HV+20%AR mixture and 20-cm row spacing interaction. These results show that increasing the HV ratio in the mixture has positive effects on the yield and quality, whereas raising the row spacing has adverse effects on the forage values. Therefore, 80%HV+20%AR or 60%HV+40%AR with a 30cm row spacing interaction can be suggested for forage production in an HV and AR intercropping system

Implications of narrow crop row spacing and delayed Echinochloa colona and Echinochloa crus-galli emergence for weed growth and crop yield loss in aerobic rice

Field experiments were conducted in 2008 and 2009 to determine growth and seed production of Echinochloa colona and Echinochloa crus-galli emerging at five intervals (0, 15, 30, 45, and 60 days after rice emergence, DARE) in aerobic rice seeded at 20- and 30-cm row spacing. Plant height of these two weed species was not influenced by the crop row, but it was influenced by the weed emergence time. Weeds of either species emerging until 30 DARE had greater biomass and more seeds under wide rows than under narrow rows, but row spacing had no effect on biomass and seeds of plants emerging later. In both crop row spacing treatments, delay in weed emergence until 45 DARE significantly reduced weed biomass. E. colona and E. crus-galli plants that emerged 60 DARE produced only 3 seeds plant −1 in 30-cm rows, whereas no seed was produced by these plants in 20-cm rows. Fitting a single linear function to the combined data for rows and weed emergence time gave a strong positive linear relationship between shoot biomass (g plant −1) and seed production (number plant −1) of these species, accounting for 94% and 93% variation in E. colona and E. crus-galli, respectively. These relationships can be used as a predictor of seed production in these species. Regardless of the weed species and weed emergence date, rice grain yields were greater in narrow rows than in wider rows. In the case of both weed species, rice grain yield improved significantly with each delay in weed emergence up to 45 DARE. The results of this study suggest that narrowing row spacing and controlling early weeds led to decreased weed growth and seed production, and increased grain yield in aerobic rice. Narrow crop row spacing and early weed control could be important components of integrated weed management strategies in aerobic rice.

Seeding Rate Effects on Weed Control and Yield For Organic Soybean Production

The organic grain sector is one of the fastest growing sectors of the organic market, but farmers in the mid-Atlantic cannot meet the organic grain demand, including the demand for organic soybean. Weed management is cited by farmers as the largest challenge to organic soybean production. Recent soybean population studies show that lower seeding rates for genetically modified organism soybean farmers provide maximum economic return due to high seed technology fees and inexpensive herbicides. Such economic analysis may not be appropriate for organic soybean producers due to the absence of seed technology fees, stronger weed pressures, and price premiums for organic soybean. Soybean seeding rates in North Carolina have traditionally been suggested at approximately 247,000 live seeds/ha, depending on planting conditions. Higher seeding rates may result in a more competitive soybean population and better economic returns for organic soybean producers. Experiments were conducted in 2006 and 2007 to investigate seeding rates of 185,000, 309,000, 432,000, and 556,000 live seeds/ha. All rates were planted on 76-cm row spacing in organic and conventional weed management systems. Increased soybean seeding rates reduced weed ratings at three of the five sites. Increased soybean seeding rates also resulted in higher yield at three of the four sites. Maximum economic returns for organic treatments were achieved with the highest seeding rate in all sites. Results suggest that seeding rates as high as 556,000 live seeds/ha may provide organic soybean producers with better weed control, higher yield, and increased profits.

Effects of winter wheat row spacing on evapotranpsiration, grain yield and water use efficiency

A field study was conducted from 2002 to 2007 to investigate the influence of row spacing of winter wheat (Triticum aestivum L.) on soil evaporation (E), evapotranspiration (ET), grain production and water use efficiency (WUE) in the North China Plain. The experiment had four row spacing treatments, 7.5 cm, 15 cm, 22.5 cm, and 30 cm, with plots randomly arranged in four replicates. Soil E was measured by micro-lysimeters in three seasons and ET was calculated from measurements of soil profile water depletion, irrigation, and rainfall. The results showed that E increased with row spacing. Compared with the 30-cm row spacing (average E = 112 mm), the reduction in seasonal E averaged 9 mm, 25 mm, and 26 mm for 22.5 cm, 15 cm, and 7.5 cm row spacings, respectively. Crop transpiration (T) increased as row spacing decreased. The seasonal rainfall interception and seasonal ET were relatively unchanged among the treatments. In three out of five seasons, the four different treatments showed similar grain yield, yield components and WUE. We conclude that for winter wheat production in the North China Plain, narrow row spacing reduced soil evaporation, but had minor improvements on grain production and WUE under irrigated conditions with adequate nutrient levels.

Timing of Maturity in Ultra-Narrow and Conventional Row Cotton as Affected by Nitrogen Fertilizer Rate

Ultra-narrow row (UNR) systems and N fertilizer can influence cotton (Gossypium hirsutum L.) crop maturation. Study objectives were to measure impacts of UNR systems and N fertilizer rates on cotton maturation and to identify mechanisms by which these effects occurred. The location was Burleson County, Texas. In the split plot design, whole plots were N rates of 0, 50, 101, and 151 kg ha−1. Split plots were 19-, 38- (both UNR), and 76-cm (conventional row, CR) row spacings with 296,600, 195,400, and 136,300 plants ha−1, respectively. Thirty, 60, and 85% harvestable seedcotton each occurred 1.5 to 2.9 d earlier in UNR than CR spacings. First boll set occurred 1 d later in 19-cm than in wider row spacings. Boll set rate m−2 was greater in 19- than 76-cm row spacing during a 5-d flowering period shortly after first boll set, but did not differ by row spacing during three flowering periods thereafter. The percentage first position bolls was lower with wider row spacing, suggesting greater potential for concurrent boll set at multiple sites on individual plants. Eventual development of nonfirst position fruiting sites in 76-cm row spacing may have contributed to confinement of faster boll set in 19-cm row spacing to early bloom. Nitrogen rates did not affect the timing of 30, 60, or 85% harvest. Reductions in bolls plant−1 were counteracted by slower boll set rates with lower N. The limited observed interactions of N and row spacing do not suggest advantages from suboptimal N rates in UNR cotton.

Effect of Weed Removal Timing and Row Spacing on Soil Moisture in Corn (Zea mays)

Glyphosate-resistant corn was grown in 38- and 76-cm row spacings at two locations in 2001 to examine the effect of weed competition and row spacing on soil moisture. Volumetric soil moisture was measured to a depth of 0.9 m in 18-cm increments. Glyphosate was applied when average weed canopy heights reached 5, 10, 15, 23, and 30 cm. Season-long weed interference reduced soil moisture compared with the weed free controls. At Clarksville, MI, where common lambsquarters was the dominant weed species, weed interference reduced soil moisture in the 0- to 18-cm soil depth from late June through early August and at the 54- to 72- and 72- to 90-cm depths from mid-July through the end of the season. At East Lansing, MI, where giant foxtail was the dominant weed species, weed interference reduced soil moisture at the 18- to 36-, 36- to 54-, and 54- to 72-cm soil depths from mid-June to the end of the season. Season-long weed competition reduced yields more than 90% at each location. Weeds that emerged after the 5-cm glyphosate timing reduced soil moisture and grain yield at both locations. Delaying glyphosate applications until weeds reached 23 cm or more in height reduced corn yield at both locations and soil moisture at East Lansing. Grain yields in the 10- and 15-cm glyphosate-timing treatments were equal to the weed-free corn, even though soil moisture was less during pollination and grain fill. Row spacing did not affect grain yield but did affect soil moisture. Soil moisture was greater in the 76-cm row spacing, suggesting that corn in the 38-cm row spacing may have been able to access soil moisture more effectively.

Nitrogen management systems to optimize spring wheat under no-till: Effects on plant development

Surface residues and standing stubble protect soil against erosion and mitigate against crop water deficits by conserving additional moisture. However, residues and stubble can also present a dilemma for producers practising no-till in terms of nitrogen (N) fertilizer management and row spacing. The objective of this research was to determine how row spacing, N management using urea and two rates of post-emergent herbicide (66 and 100% of recommended) affect spring wheat establishment and plant development. The study was conducted using a no-till system and a canola-springwheat cropping system at three locations over a 3-yr period. The N management and row spacing treatments were (1) 23-cm row spacing with fall banded N on 30 cm; (2) 23-cm row spacing with spring banded N on 30 cm; (3) 30-cm row spacing with the N side-banded; (4) 23-cm row spacing with the N side-banded; and (5) sweep on 23-cm spacing with seed and fertilizer scattered over a 20-cm width. Herbicide rates did not affect wheat development. Planting depth was greater for the sweep treatment, but only by 6 mm. Plant densities were at the low end of the optimal range of 200–250 plants m-2 for all treatments and were least for the 30 cm row spacing. Average frequencies for tillers T0, T1, T2 and T3 were 20, 81 61 and 10%, respectively. Fall and spring band treatments resulted in lower tiller frequencies than the sweep treatment, with intermediate levels for the side-band treatments. Tiller frequencies were identical between the 23-cm and 30-cm row spacings with N side-banded. Greater tiller frequencies for the sweep treatment likely resulted from the greater spread of seed, reducing inter-plant competition and closer proximity of the seed to fertilizer N. Spike density was not affected by N management. Expected spike density, calculated from tiller frequency and plant density data, was within 1% of the actual spikes recorded, when averaged over treatments. This means that tiller frequencies at the 5 to 5.5 leaf stage are a good predictor of expected spike density. Wider row spacings did not affect plant and tiller development but applying N fertilizer at time of seeding provided better spring wheat tiller development. Key words: Triticum aestivum L., nitrogen management, tiller development

Impact of seedbed utilization and fungicide application on severity of net blotch [Pyrenophora teres] and production of barley

Limited information is available regarding the impact of seed placement and row spacing, and their interaction with fungicides, on leaf diseases and agronomic performance of barley. A direct-seeding field experiment was conducted at three locations in Canada (Lacombe and Beaverlodge (Alberta) and Melfort (Saskatchewan)), in 1999–2000, to evaluate the effect of three seedbed utilization treatments and six foliar fungicide timing and rate treatments on disease severity and production characteristics of barley. Seedbed treatments included row spacing at 23 or 30 cm with a knife opener, or spread bands with a 28-cm sweep and a 23-cm row spacing. Fungicide treatments included full and split applications of propiconazole at Zadoks growth stages (GS) 12, 37, and 58 with an untreated control. Severity of net blotch [Pyrenophora teres] was higher for the 23- and 30-cm distinct row spacings compared with the spread-band placement using sweeps. The interaction between seed placement and fungicide application was not significant for net-blotch severity, indicating that disease response to fungicide did not vary with seed-placement configuration. Overall, grain yield was affected by seed placement, with the spread band having slightly higher yield, especially when compared with the 30-cm distinct row spacing, but the response to seed placement did vary over year × location combinations, and with fungicide treatment. Kernel weight, plumpness, and test weight were greatest for the spread-band placement, although this response varied among year × location combinations. Fungicide applications at late growth stages (GS 37 and GS 58) reduced net-blotch severity and increased grain yield and kernel quality, whereas applications at GS 12 generally had a limited impact. Planting in distinct rows may have resulted in higher disease severity and lower kernel weight, plumpness, and test weight by facilitating spore dispersal and subsequent net-blotch development compared with the spread-band placement.

Detecting weed-free and weed-infested areas of a soybean field using near-infrared spectral data

Weed distribution maps can be developed from remotely sensed reflectance data if collected at appropriate times during the growing season. The research objectives were to determine if and when reflectance could be used to distinguish between weed-free and weed-infested (mixed species) areas in soybean and to determine the most useful wavebands to separate crop, weed, and soil reflectance differences. Treatments included no vegetation (bare soil), weed-free soybean, and weed-infested soybean and, in 1 yr, 80% corn residue cover. Reflectance was measured at several sampling times from May through September in 2001 and 2002 using a handheld multispectral radiometer equipped with band-limited optical interference filters (460 to 1,650 nm). The spatial resolution was 0.8 m2. The reflectance in the visible spectral range (460 to 700 nm) generally was similar among treatments. In the near-infrared (NIR) range (> 700 to 1,650 nm), differences among treatments were observed from soybean growth stage V-3 (about 4 wk after planting) until mid-July to early August depending on crop vigor and canopy closure (76-cm row spacing in 2001 and 19-cm row spacing in 2002). Reflectance rankings in the NIR range when treatments could be differentiated were consistent between years and, from lowest to highest reflectance, were soil < weed-free < weed-infested areas. Increased reflectance from weed-infested areas was most likely due to increased biomass and canopy cover. Residue masked differences between weed-free and weed-infested areas during the early stages of growth due to high reflectance from the residue and reduced weed numbers in these areas. These results suggest that NIR spectral reflectance collected before canopy closure can be used to distinguish weed-infested from weed-free areas.

Corn and Soybean Response to Rotation Sequence, Row Spacing, and Tillage System

Row spacing less than 76 cm for corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] is becoming more common. However, little information is available on row spacing in different rotation sequences. The objective of this study was to determine the influence of rotation sequence, row spacing, and tillage system on corn and soybean yield. Corn and soybean were planted in 19-, 38-, and 76-cm row spacing in conventional tillage and no-tillage systems. Both crops were compared in seven rotation sequences. Few interactions were found between row spacing and tillage or between row spacing and rotation sequence for corn or soybean yield. Corn grain yield decreased 11% using the 19-cm row spacing compared with the 38- and 76-cm row spacings. Corn grain yield decreased 5% using the no-tillage system compared with the conventional tillage system. Corn rotated annually with soybean and first-year corn after 5 yr of consecutive soybean yielded 15% more than continuously grown corn. Soybean yield was not affected by row spacing. No-tillage soybean yield was 6% higher than the conventional tillage system. First-year soybean after 5 yr of consecutive corn yielded 8% more than the other six rotation sequences. We concluded that corn–soybean cropping history and tillage system were not important for determining optimum row-spacing system for corn or soybean. The use of a row-spacing system less than 76 cm was not beneficial for either crop.

Row-Spacing Interactions on Spring Canola Performance in the Northern Great Plains

Introduction of hybrid and transgenic spring canola (Brassica napus L.) cultivars and production in a new geography prompt performance evaluation of these cultivar types. The objective was to determine interactions for commonly used research and commercial production row spacings with canola performance using contemporary open-pollinated, hybrid, and transgenic cultivars. Two North Dakota rainfed sites were used during 1999, 2000, and 2001. Row spacings of 15 and 30 cm constituted the main plot, and one B. rapa and three B. napus cultivars (conventional and transgenic) comprised the subplot. Characters evaluated were days to first flower, duration of flowering, plant height, seed yield, plant lodging, and seed oil content. Row spacing and the row spacing × cultivar interaction were only significant for plant height. Shorter plant height for the B. rapa cultivar was found when grown at the narrower row spacing, but B. napus cultivars had similar plant height at both row spacings. The B. rapa cultivar had fewer days to first flower, shorter plant height, and lower yield than the B. napus cultivars. The hybrid B. napus cultivar yielded greater than the open-pollinated cultivars. Cultivars did not differ for duration of flowering, plant lodging, and seed oil content. The environment × cultivar interaction showed greater character values at the northern Langdon environments compared with southern Prosper environments. Yield and seed oil content, the primary characters determining crop value, were not affected by row spacing. Similar crop performance from 15- and 30-cm row spacings enables growers and researchers to utilize existing seeding equipment for optimum canola production.

Effect of Row Spacing and Herbicide Application Timing on Weed Control and Grain Yield in Corn (Zea mays)1

Field experiments were conducted from 1997 to 1999 at the University of Minnesota Southern Research and Outreach Center in Waseca to evaluate the (1) effect of corn row spacing on grass and broadleaf weed species density and height, (2) optimal herbicide application timing in narrow- and wide-row systems, and (3) corn grain yield response to row spacing and herbicide application timing. Corn was planted in 51- and 76-cm row spacings. Within each row-spacing treatment, there were five herbicide application timings: a formulated mixture of acetochlor plus atrazine applied preemergence or a formulated mixture of imazethapyr and imazapyr tank-mixed with bromoxynil applied postemergence at 5-, 10-, 20-, or 30-cm giant foxtail plant height. Reducing the row spacing in corn from 76 to 51 cm did not influence early-season weed emergence or growth. Similarly, late-season weed density and growth were not influenced by row spacing except in 1997. But corn grain yield increased when corn was planted in narrow rows compared with wide rows in 2 out of 3 yr when averaged over herbicide application treatments. Herbicide application timing had a significant effect on late-season weed density and grain yield. But there was no interaction between herbicide application timing and row spacing on grain yield. Potential increases in crop competitiveness resulting from narrow-row corn did not appear to affect weed density or growth in this study.Nomenclature: Acetochlor; atrazine; bromoxynil; imazapyr; imazethapyr; giant foxtail, Setaria faberi Herrm. #3 SETFA; corn, Zea mays L. ‘Pioneer 3751IR’.Additional index word: Integrated weed management.Abbreviations: POST, postemergence; PRE, preemergence.

Effect of row spacing ;and seed rates on the yield of buckwheat (Fagopyrum esculentum)

A field experiment on buckwheat (Fag.opymnt esculentum Moench) was conducted during the rainy seasons (kharij) of 1990 and 19911 under rainfed conditions at Ranichauri. Sowing of buckwheat at 30 cm gave the maximum seed yield (18.35 qlha), being 14.8 and 26.9% higher than 20 and 40 cm row spacings respectively. The highest stalk yield and harvest index (15.97%) were recorded with 30-cm row spacing. The sowing of seed @ 30 kglha gave the maximum seed yield (18.36 qlha), followedby 20 kg seedlha. The stalk yield (98.38 qlha) and harvest index (15.73%) were highest with 30 kg/ha seed rate.