In-row Spacing Research Articles

Effect of in-row spacing on weed suppression and yield of ‘Covington’ and ‘Monaco’ sweetpotato

Abstract Organic sweetpotato growers have limited effective weed management options, and most rely on in-season between-row cultivation and hand weeding, which are time consuming, are costly, and deteriorate soil quality. Studies were conducted at the Samuel G. Meigs Horticulture Research Farm, Lafayette, IN, and at the Southwest Purdue Agricultural Center, Vincennes, IN, in 2022 and 2023 to determine the effects of in-row plant spacing and cultivar selection on weed suppression and organic sweetpotato yield. The experiment was a split-split plot design, with in-row spacings of 20, 30, and 40 cm as the main plot factor, weeding frequency (critical weed-free period and weed-free) as the subplot factor, and sweetpotato cultivar (‘Covington’ and ‘Monaco’) as the sub-subplot factor. However, in 2022, we evaluated only in-row spacing and weeding frequency because of the poor establishment of ‘Monaco’. In 2023, sweetpotato canopy at 5 wk after transplanting (WAP) decreased as in-row spacing increased from 20 to 40 cm, and sweetpotato canopy cover of ‘Monaco’ (62%) was greater than that of ‘Covington’ (44%). In-row spacing did not affect weed density at 4, 5, and 6 WAP. As in-row spacing increased from 20 to 40 cm, total sweetpotato yield pooled across both locations in 2023 decreased from 30,223 to 21,209 kg ha−1 for ‘Covington’ and from 24,370 to 20,848 kg ha−1 for ‘Monaco’; however, jumbo yield increased for both cultivars. Findings from this study suggest that an in-row spacing of 20 cm may provide greater yield than the standard spacing of 30 cm for both ‘Monaco’ and ‘Covington’.

High-density Planting and a Smaller Row Width Increased Yield and Decreased Fruit Size of Pumpkins

Pumpkins (Cucurbita sp.) grown in North Carolina are a nascent specialty crop that has only risen to a national production level in the past 10 years. There are only general cultural management guidelines for this region, resulting in variation in plant density and inefficient production. Production field studies of the cultivar Kratos were conducted to investigate the impact of plant density and row width on marketable yield and individual fruit size for large carving pumpkins. Plant densities of 2691, 3588, 5382, and 10,764 plants per hectare with row widths of 1.5 and 3.0 m were grown in 2020 and 2021 in North Carolina. Data regarding fruit size, fruit size variance, and yield per area were collected. Fruit size in terms of weight, length, and diameter increased as plant density decreased. There was no difference in fruit size variation between plant densities and row widths. The fruit number per hectare and fruit weight per hectare increased as plant density increased, with the highest production at 10,764 plants per hectare. For years combined, reducing the row width from 3.0 to 1.5 m increased the fruit weight and diameter, but not the length. Additionally, the 1.5-m row width produced more fruit weight per hectare than the 3.0-m row width for both years. Growers can optimize fruit weight per area and fruit number per area by using a density of 10,764 plants per hectare. Overall, using a row width distance that is more equidistant to the in-row spacing promotes higher fruit yield and larger fruit size.

Plant Density Recommendations and Plant Nutrient Status for High Tunnel Tomatoes in Virginia

Open-field tomatoes in Virginia are traditionally planted in a single row with 2 ft (0.60 m) of in-row spacing, resulting in a plant density of 4356 plants per acre (10,890 plants/ha). However, there has been increasing interest among small and medium-sized farmers in high tunnel production. In order to be profitable, farmers must maximize their yield per unit area and take advantage of the potential benefits of producing under high tunnels. A common approach under greenhouse conditions is to increase the planting density to enhance yield per area. However, high tunnel farmers often extrapolate open-field practices to their high tunnels as they believe both systems are closer related together than to greenhouse production. In those cases, high tunnel farmers could potentially be neglecting yield increases due to their planting density selection. Additionally, irrigation and fertilization management (fertigation) under high tunnels tend to be more efficient than open-field systems, as the frequency of application is increased with a lower volume per application. A higher efficiency of fertigation could alter plant yield responses, especially under traditional planting-density systems. Hence, this study aimed to identify the effect of high planting density on high tunnel tomatoes and their nutrient status on the Eastern Shore of Virginia. The experiment was established on a completely randomized block design with four replications, with 20 ft (6.09 m) experimental plots. We evaluated the combination of two in-row distances and single and double planting rows, with treatments consisting of 2 ft of in-row distance in a single row (4356 plants/acre—current open-field recommendation), 1.5 ft (0.45 m) of in-row distance in a single row (5808 plants/acre [14,520 plants/ha]), 2 ft of in-row distance in a double row (8712 plants/acre [21,780 plants/ha]), and 1.5 ft of in-row distance in a double row (11,616 plants/acre [29,040 plants/ha]). Summer-grown tomatoes produced on the Eastern Shore of Virginia under high tunnel conditions should be planted with 2 ft of in-row spacing and with a single row of plants per planting bed. Increasing the plant density or modifying the current recommended plant distribution could result in yield losses per plant between 32% and 46% and substantial increases in production costs compared with the traditional planting density. Throughout all treatments, tomato plants did not show deficient nutrient status. We hypothesized that irrigation water and pollination were the limiting factors that promoted a decrease in yield per plant for the high-density treatments.

Summer Mechanical Hedging to Prune Eight Cider Apple Cultivars

Mechanical hedging was evaluated at Washington State University Northwestern Washington Research and Extension Center, Mount Vernon, WA, in 2019 and 2020 on eight cider apple (Malus ×domestica) cultivars with four bearing habits: tip—Golden Russet, Harrison; spur—Brown Snout, Cap of Liberty; semispur—Tom Putt, Campfield; and crab—Puget Spice, Hewe’s Virginia Crab. Trees were planted on ‘Geneva 935’ (Malus hybrid) rootstock in one replicate block in 2014 and the second replicate block in 2016 and the central leader of all trees was headed in 2017 to equalize tree size and stage of development. Summer hedging was carried out on all cultivars on 16 July in 2019 and 7 July in 2020. The response of different cultivars was evaluated both years by measuring canopy area removed, shoot biomass removed, and fruit removed, and the amount of time to hedge was measured. Additionally, fruit diameter and fruit yield per tree were measured at harvest both years, and fruit weight was measured at harvest only in 2020. The hedger traveled at an average speed of 1.32 mph; it took 6 seconds on average to hedge both sides of one tree when in-row spacing was 6 ft and took 1.25 minutes to maneuver around the end of a row. The estimated time to hedge 1 acre was 1.45 hours when the hedger traveled at 116 ft/min and the orchard had 10 rows spaced 12 ft apart. Biomass removed on an area and weight basis was less in 2020 than in 2019, whereas yield per tree was 2.6 times greater in 2020 than 2019, and cultivars within a bearing habit differed in these responses to hedging both years. Fruit damaged by the hedger was assessed but observed to be negligible for all cultivars. Yield per tree was negatively correlated with fruit diameter (P < 0.001) and positively correlated with the number of fruit removed per tree (P < 0.025). Further research is needed to assess the long-term effects of hedging on biomass removal, yield, and biennialism to determine whether summer mechanical hedging is a cost-effective and suitable method for managing cider apple orchards.

Plastic Mulch and In-row Spacing Effects on Sweetpotato Yield in Northwest Washington

Sweetpotato (Ipomoea batatas) production in the northern United States is limited due to the perceived barriers of a short growing season and relatively cool summer temperatures, yet recent studies have shown yield in northern regions can be greater than the national average when sweetpotatoes are grown with plastic mulch. A study was conducted in northwest Washington to evaluate the productivity of ‘Covington’ sweetpotato with polyethylene (PE) and soil-biodegradable (BDM) mulches and different in-row spacings (20, 30, and 38 cm) in 2019, and to test accessions resistant to wireworm (Agriotes sp. and Limonius sp.) in 2020. In 2019, slips were shipped from North Carolina, and after 4 days in transit, 60% to 70% died after transplanting in the field. By the end of the season, BDM deterioration reached 11% compared with 0.4% for PE mulch, but there were no differences due to mulch in plant establishment, growth, yield, or the proportion of storage roots damaged by wireworm. Total storage root yield was 22 t⋅ha−1 with PE mulch and 15 t⋅ha−1 with BDM. Percent canopy cover was greatest at 20-cm spacing later in the growing season, likely due to intermingling of vines from adjacent plants, whereas high percent canopy cover at 38-cm spacing was likely due to increased production of secondary vines per plant. Total yield was greatest with 20-cm plant spacing (20.4 t⋅ha−1), intermediate with 30-cm spacing (18.0 t⋅ha−1), and lowest with 38-cm spacing (17.0 t⋅ha−1). In contrast, the greatest number of storage roots per plant was produced with 38-cm plant spacing (3.4). There were more jumbo sweetpotatoes produced with PE mulch (3.4 t⋅ha−1) and with 30-cm spacing (3 t⋅ha−1), and the weight of U.S. No. 2 grade sweetpotatoes was greatest at 20-cm spacing (10.2 t⋅ha−1). Soil temperature was increased by 3 °C under the PE mulch and 2 °C under the BDM compared with bare ground. However, 98% of storage roots were observed to be severely damaged by wireworm in 2019, with more than 10 to 20 holes per storage root. For wireworm-resistant accessions in 2020, 16% of the storage roots were damaged by wireworm, with 1.7 to 4.0 holes per storage root. Total yield of accessions PI 666141 and 04-791 (45.5 t⋅ha−1 on average) was greater than the national average (24.7 t⋅ha−1). Overall, sweetpotatoes appear to be suitable for production in northwest Washington, but low yield in 2019 highlights the importance of healthy slips for successful production. Future research should evaluate cultivars with maximum adaptation to the region, techniques to reduce wireworm damage including genetic resistance, and the economics of producing sweetpotatoes in northern regions.

Modelling the effect of variation of in-row spacing on kernel m-2 in maize

Maize (Zea mays L.) yield is often reduced when the in-row plant spacing is not uniform. I used a variant of the KNMAIZE model to investigate the mechanisms responsible for the reductions. KNMAIZE determines kernels per plant from the relationship between the proportion of the assimilate supply from photosynthesis that is partitioned to the kernels and the assimilate required to sustain kernel growth. Kernels abort when their assimilate requirement exceeds the supply. Algorithms were developed to create variation of in-row plant spacing (characterized by CV) and emergence percentage. The effect of spatial variation on kernels m−2 depended upon the ability of the dominant plants (higher plant growth rates associated with larger in-row spacing’s) to increase kernels per plant to compensate for the reduction on the dominated plants (lower plant growth rates resulting from smaller in-row spacing’s). When the ability of the dominant plants to respond was zero (kernels ear−1 = florets ear−1, excess capacity = 0), kernels m−2 started decreasing as soon as the CV > 0. When the dominant plants had excess capacity (i.e., kernels per ear < florets per ear), the beginning of the decline occurred at progressively larger CVs depending upon the magnitude of the excess capacity. Populations greater than the minimum needed for maximum yield provide the excess capacity on dominant plants to buffer kernels m−2 and yield against variation of in-row spacing and reductions in emergence.

A Win–Win Situation: Performance and Adaptability of Petite Sweetpotato Production in a Temperate Region

New-found interest in sweetpotato production in the Mid-Atlantic and Northeastern U.S. has been steadily increasing in the last several years. Sweetpotatoes are usually grown for fresh market use and novel marketing strategies and new consumer niches are providing farmers options of growing new sweetpotato varieties with exciting colors and flavor profiles that are adapted to the Mid-Atlantic and Northeastern U.S. Petite sweetpotatoes have gained market attention because they are easier to handle and faster to cook compared to U.S. No. 1 storage roots. The goal of this research was to determine the performance and adaptableness of eight commercial sweetpotato varieties and two unreleased accessions for U.S. No.1 and Petite sweetpotato production under black plastic mulch tailored for the mild temperate growing conditions of the Mid-Atlantic and Northeastern U.S. Two in-row spacings (15 cm and 30 cm) and two harvest dates (90 and 120 days after planting, DAP) were evaluated during the 2018 and 2019 growing seasons. Our results showed that the ideal harvest time is at least 120 DAP compared to an early harvest at 90 DAP as there was a 2-fold difference in marketable yield at both 15 and 30 cm in-row spacing with marketable yield between 20 and 54 t ha−1. ‘Averre’ and ‘Beauregard’ produced the highest U.S. No. 1 and Petite yields under both in-row spacing treatments harvested at 120 DAP for both years evaluated, though the general effect of in-row spacing and DAP interaction (separate years) on yield performance was cultivar specific. We also found that growing degree days is a better predictor for harvest than days after planting, with an accumulation of at least ~700 GDD (base temperature 15.5 °C) or ~1300 GDD (base temperature 10 °C) for both U.S. No. 1 and Petite roots. Additional studies are required to identify the stability of cultivars tested and treatments imposed with environmental interactions in this region. In addition, there is an urgency for updated sweetpotato management practices exclusively designed for sweetpotato varieties for the Mid-Atlantic and Northeastern U.S.

The Features of Taxonomic Structure Formation of Soil Microbial Biome in Beta vulgaris Rhizosphere

The necessity to increase the production of quality agricultural products in order to minimize using of agrochemicals while maintaining high profitability of production are required a comprehensive study of the determining factor of soil fertility – its biological component. Research of the microbiocenoses formation in the plants rhizosphere at all ontogenesis stages will allow to uncover the mechanisms of microbial-plant interaction and develop effective ways to increase crop productivity with high functional activity and homeostasis of the soil microbiome. The goal is to study the structure of the microbial complex and biodiversity of Beta vulgaris rhizosphere during ontogenesis by classical microbiological and molecular-biological methods. Methods. The number of microorganisms was determined by the method of inoculation soil microbial suspension on agar nutrient media, the structure of the qualitative composition of microorganisms was identified by morphologically-cultural properties, the morphology of isolated isolates – by microscopy of fixed preparations. The diversity of soil microbial complexes was evaluated by the Shannon, Simpson, and Berger-Parker ecological indices. The taxonomic structure of prokaryotes was determined by pyrosequencing. Results. The differentiation of the soil microbiota number was observed during the Beta vulgaris ontogenesis due to the intensity production of root exudates by the plant. The number of bacteria and micromycetes are increased 1.8–2.3 times, however, in the phase of leaves closing in-row spacing, the number of fungal microbiota decreased by 46.4%. Microbial complexes were differed in the number of detected morphotypes (27–50) and in the structure of the distribution of dominant forms (the total number of dominant forms of bacteria was decreased during the growing season, micromycetes – was increased). Analysis of the prokaryotes metagenome by pyrosequencing made it possible to identify 214 operational taxonomic units, 10.1% of which are forms that are not cultivated on nutrient media, 23.3% are unclassified. Among the identified taxonomic units, 96.2% were identified at the order level, 85.7% – at the family level, 76.7% – at the genus level. Among the identified taxonomic units were 15 phyla bacteria and 1 – archaea, among which 96 taxonomic units, families – 167, genera – 214 we found at the level of microbial orders. The dominant forms among the identified phyla were Proteobacteria (65.7%) and Actinobacteria (20.5%); orders – Burkholderiales (38.7%) and Pseudomonadales (20.1%); families – Alcaligenacea (37.9%), Pseudomonadaceae (20.1 %); Gaiellaceae (5.7%), Nitrososphaeraceae (4.2%); genera – Achromobacter (31.5%) and Pseudomonas (19.9%). The soil microbial complex was characterized by high biodiversity according to the indicators According to the indicators of ecological indices, determined on the basis of the results of classical microbiological and molecular biological research methods, it is established that the microbial complex of the soil was characterized by high biodiversity. Although the Shannon (ISh=5.36) and Simpson (IS=0.87) indexes, based on the pyrosequencing method results, were significantly higher than similar indicators identified by classical microbiological methods. Conclusions. During the ontogenesis of Beta Vulgaris, including due to the intensity of plant production of root exudates, the number of bacteria and micromycetes in the rhizosphere of plants increased. It was accompanied by a redistribution of structural composition and an increase of the microorganisms’ diversity (ISh=5.36). It found that among the identified 214 taxonomic units, 10.1% – forms that are not cultivated on nutrient media, 23.3% – are unclassified. Our studies showed that the structure of the microbial complex of the plants’ rhizosphere reflects the characteristics of the soil and can be used as an indicator of ecological status. The obtained results (conducted for the first time in the Forest-Steppe of Ukraine) deepen the knowledge about the true scale of natural genetic diversity of microbial complexes and are a valuable asset for substantiating practical proposals for effective adaptive interactions in the plant-microorganism system to preserve the homeostasis agroecosystems.

Growth habit and in-row distance for bell pepper under protected culture

ABSTRACT Bell pepper (Capsicum annuum L.) production under high tunnels requires appropriate plant density and growth habit to ensure efficient use of space. This study assessed the effects of in-row spacing and bell pepper growth habit on growth and yield under high tunnels. Determinate, cv. Crusader, and indeterminate, cv. Maria, seedlings were transplanted in single rows spaced at 20, 25, and 30 cm between plants (equivalent to 31,245; 24,996; and 20,830 plants∙ha−1, respectively) with growth habit as the main plot and in-row distance as sub-plot. Leaf greenness, plant nutrient status, plant height and marketable fruit weight and number were measured. Yield per plant and per unit area were affected by growth habit and in-row distance. The indeterminate cultivar produced 33% more fruit and 13% more yield per plant than the determinate cultivar, while the determinate cultivar produced 24% heavier fruit than the indeterminate cultivar. In-row distances of 20 and 25 cm resulted in similar fruit number per hectare, while 30 cm plant spacing reduced fruit per hectare by 20%. Overall yield was not affected by in-row distance. An economic analysis is necessary to evaluate the potential profitability of a bell pepper system based on indeterminate cultivars and an in-row distance of 30 cm.

Managing eucalyptus trees in agroforestry systems: Productivity parameters and PAR transmittance

Agroforestry systems, in which trees and crops are cultivated in rotation, succession, or association with pastures, are alternatives for the sustainable implementation of agriculture. This study estimated the productive characteristics from eight years old eucalyptus trees in different agroforestry systems and transmission of photosynthetically active solar radiation (PAR). These were composed of a pasture of palisade grass (Urochloa brizantha “BRS Piatã”) and eucalyptus trees (Eucalyptus urograndis “GG100”) planted in April 2011 in single rows 15 m apart with 2 m in-row spacing, totaling 333 trees ha−1. In 2016, half of the trees were thinned, and the spacing was changed to 15 × 4 m. The two systems were then evaluated using an integrated crop-livestock-forestry system (agrosilvopasture with pasture renewal, ICLF) and an integrated livestock-forest system (silvopasture with no pasture renewal, ILF). Each system had 12 paddocks of 5000 m2. In ICLF, pasture was renewed in one-third of each replication of area (two paddocks) per crop year, where the grass was simultaneously sown with corn for silage. Pasture renewal was carried out in the 2013–2014, 2014–2015, 2016–2017, and 2017–2018 growing seasons. Data were collected in April 2016 and June 2019, when 110 trees were harvested to determine wood volume and 28 to gather wood rings and samples of the canopy, roots, and carbon content. These data were used to build the equations for estimating stem volume (m3 tree−1) and tree biomass (kg tree−1). Stem diameter at breast height (DBH, 1.3 m above the ground) and tree height (H) were measured in 10% of the trees in each plot to estimate stem volume and biomass; these were compared by t-test (5%). PAR was measured continuously from 2013 to 2019 at 70 cm aboveground with linear quantum sensors at the four ICLF positions across the tree line. Using these data, equations for volume = exp[(− -10.21 + 1.68 × ln(DBH)+1.29 × ln(H)] and biomass = exp[−3.88 + 2.41*ln(DBH)+0.62 × ln(H)] were built. The stem volume was greater in ICLF (225.7 m3 ha−1) than in ILF (215.2 m3 ha−1) (p = 0.0369). The total biomass was 148.3 Mg ha−1 for ICLF and 141.0 Mg ha−1 for ILF, with no significant differences between systems. The agroforestry systems accumulated 64.5 Mg ha−1 of carbon in tree biomass by eight years after system implementation. The basal area of trees in both agroforestry systems showed a strong relationship with the transmission of PAR to the pasture.

Effects of Within-row Intercropping with Snow Peas on Yield and Quality of Cherry Tomatoes in an Organic High Tunnel Production System

Intercropping can increase land use efficiency in high tunnel crop production, but it may also lead to decreases in yield and quality of main crops due to the potential competition for resources. This study evaluated the agronomic viability of intercropping snow pea (Pisum sativum L., ‘Ho Lan Dou’) with cherry tomato (Solanum lycopersicum L. var. cerasiforme ‘Sarina hybrid’) without additional inputs of water and fertilizers on peas in an organic high tunnel production system under Southern Ontario climate conditions in Guelph, Ontario, Canada (lat. 43.5 °N, long. 80.2 °W) during 2015 and 2016. In each 80-cm-wide bed, the tomato crops were planted alternately in double rows spaced 30 cm apart, with in-row spacing of 110 cm, which resulted in a planting density of ≈24,000 plants/ha. The snow pea seeds were sown between the tomato plants (i.e., within the same beds as tomatoes) in holes (two seeds per hole), with four rows in each bed and in-row holes spaced 10 cm and at least 25 cm away from the tomato plants, which resulted in a seeding rate of ≈650, 000 seeds/ha. The same amount of water or fertilizer was applied to the intercropping and nonintercropping plots based on the needs of the cherry tomato plants. Plant growth, fruit yield, and quality were compared between tomato plants with and without intercropping. Intercropping with snow peas did not affect total marketable fruit yield, unmarketable fruit percentage, fruit quality traits (e.g., individual fruit weight, soluble solids content, dry matter content, and postharvest water loss), or early-stage plant growth of the cherry tomato. Therefore, it is at least an agronomical possibility to intercrop snow peas with cherry tomatoes on the same beds without additional inputs of water and fertilizer on snow peas in an organic high tunnel system. The additional yield of pea shoots or pods in the intercropping treatment also increased economic gross returns in the high tunnels, although the economic net return might vary with the costs of seeds and labor involved in snow pea growing.

Optimization of Seed Potato (Solanum tuberosum L.) Production: Effects of Pre-Sowing Gibberellic Acid Treatments and Planting DensityOptimization of Seed Potato (Solanum tuberosum L.) Production: Effects of Pre-Sowing Gibberellic Acid Treatments and Planting Density

Bu araştırma, tohumluk patates yumrusu üretiminde dikim öncesi gibberellik asit uygulamaları ile dikim sıklığının etkinliklerinin belirlenmesi amacıyla Isparta koşullarında 2016 ve 2017 yıllarında yürütülmüştür. Çalışmada, dikimden önce tohumluk yumrulara 0, 1.5, 3.0 ve 4.5 ppm dozlarında GA3 uygulanmış ve yumrular 20, 25 ve 30 cm sıra üzeri mesafelerde dikilmiştir. GA3 uygulamaları patateste ana sal sayısı, ocakta yumru sayısı, tohumluk yumru verimi ve toplam yumru verimini önemli derecede arttırmıştır. Dikim sıklığı arttıkça ocakta yumru sayısı, ocak verimi ve ortalama yumru ağırlığı azalmış, tohumluk yumru verimi ile toplam yumru verimi ise artmıştır. Tohumluk yumru verimi bakımından en etkili uygulamalar 3.0 ve 4.5 ppm GA3 uygulanarak 20 cm sıklıkta yapılan dikimler olmuş, bu uygulamalar ile A sınıfı tohumluk yumru veriminde yaklaşık % 57, B sınıfı tohumluk yumru veriminde ise % 88 artış sağlanmıştır. Çalışmada patates yumrularının dikim öncesi 3.0 ppm GA3 uygulanarak 20 cm sıra üzeri mesafede dikilmeleri ile toplam yumru veriminde azalma olmadan tohumluk sınıfına giren yumru veriminin arttırılabileceği anlaşılmıştır

In-row spacing and shoot thinning for ‘Chardonnay’ grapevines in the south of Minas Gerais, Brazil

ABSTRACT: The quality of sparkling wine reflects the climate and management of vineyard, since these factors affect grape development, berry composition, and base wine composition. ‘Chardonnay’ vines were subjected to five in-row spacing distances (0.5; 0.75; 1.0; 1.50; and 2.0 m) combined with and without shoot thinning. For each in-row spacing, vines were thinned to 5, 8, 10, 15, and 20 shoots per plant. Vegetative growth, yield, berry composition and base wine composition were analyzed for two years. Vines with decreased in-row spacing, presented fewer clusters and malic acid content in berries, mostly related to the shading effect. Shoot thinning increased bud fruitfulness and decreased leaf area per meter, leaf area per plant, and leaf layer number. In-row spacing from 1.5 m to 0.5 m showed promising results for the Southeast Brazil with higher yield per hectare and sufficient acidity to provide freshness in sparkling wines.

Plant Growth Response of Black Cohosh to Shade Levels in a High Tunnel

Black cohosh (Actaea racemosa L.), a medicinal herb commonly used in herbal supplements for the treatment of various ailments, is a perennial herb that grows naturally under shade conditions in temperate forest regions. This project studied the growth and rhizome yield of Black cohosh under shade conditions of 0%, 40%, 60%, and 80% in a high tunnel (9.1 m wide × 29.3 m long) on the North Carolina Agricultural and Technical University Farm. Seed rhizomes were planted in raised beds incorporated with 9070 kg/acre compost and preplant fertilizer on 29 May 2016. There was one row per bed, with in-row spacing at 45.7 cm, and one drip line per bed for irrigation. Fertigation was done weekly through the drip tapes with Multi-K 13–0–46 (27.2 kg N/acre) during the growing season. Beds were mulched after sprouting. Growth data of fully mature plants were collected on canopy width and length, total number of stems per plant, stem diameter, and length/height; and rhizome fresh and dry weight. Data were analyzed at the 0.05 level of significance. Plant canopy, stem diameter, and length/height were significantly greater in 40% shade (average, 504.7 × 472.6 mm, 3.7 mm, and 135.9 mm, respectively) than in other shade conditions, with the smallest sizes in 0% shade (average, 255.8 × 255.7 mm, 2.1 mm, and 95.4 mm, respectively). There were no significant differences between the 60% and 80% shade conditions in plant canopy, stem diameter, and length/height. However, the total number of stems per plant (4.9) in 0% shade was significantly more than those in other shade conditions, with the least of stems per plant (2.9) in 80% shade. Rhizome fresh and dry weight per plant were the greatest (164.6 and 48.1 g, respectively) in 40% shade, and the least (77.8 and 22.5 g, respectively) in 0% shade. The results indicate that optimum growing conditions for Black cohosh was in 40% shade with a Daily light integral (DLI) between 15 and 0 mol/m2/day, and a day- and nighttime temperature difference between 8.3 and 2.7 °C.

The Impact of Weeding Regime, Planting Density, and Growth Habits on Watermelon Yield in an Organic System

The southeastern United States produces 50% of U.S. conventional watermelon (Citrullus lanatus) but only 7% of U.S. organic watermelon. Weeds are a major threat to watermelon yield in the southeastern United States, and organic weed control is estimated to cost 20-times more than conventional herbicide programs. The objectives of this study were to determine the optimal weed control regime to reduce hand-weeding costs while maintaining yield and to compare the weed suppression of two watermelon types with differing growth habits in an organic system. In 2014 and 2015, watermelon plots were randomly assigned to the following treatments in a factorial arrangement: vine or compact growth habit; 1.0- or 0.5-m in-row spacing; and weekly weed control (kept weed-free by hoeing and hand-pulling weeds) for 0, 4, or 8 weeks after transplanting (WAT). At the time of the watermelon harvest, not weeding resulted in average total weed densities of 86.6 and 87.0 weeds/m2, and weeding for 4 WAT resulted in average total weed densities of 26.4 and 7.0 weeds/m2 in 2014 and 2015, respectively. Nonetheless, weeding for 4 WAT resulted in watermelon yields and fruit counts comparable to those of weeding for 8 WAT during both years. This partial-season weeding regime resulted in 67% and 63% weeding cost reductions for vine and compact plants, respectively, in 2014, and a 43% reduction for both growth habit types in 2015. In 2015, a separate experiment that evaluated weeding regimes that lasted 0, 1, 2, 3, 4, and 8 WAT found that yields resulting from weeding for 3 WAT were greater than those resulting from weeding for 2 WAT. However, the yields did not differ when weeding was performed for 4 WAT and 8 WAT.

Comparison of two planting systems for several pear cultivars

Choice of orchard system is one of the major factors, on which pear crop size and quality depend. The purpose of this research was to assess the influence of two training systems involving trees trained to different number of leaders on growth, yield, and fruit quality of three pear cultivars. The study was conducted in 2001–2012 near Wrocław (south-western Poland). One-year-old trees of ‘Carola’, ‘Dicolor’ and ‘Erika’ cultivars on the Quince S1 rootstock were planted in the spring 2001 using 3.5 m between rows and a variable in-row spacing: 1.7 m (Drilling form with 3 leaders) and 1.2 m (Güttingen – V system with 1 leader). More vigorous growth was observed from more sparsely planted trees under the Drilling form. The total per-tree yield during 2002–2012 was decreasing as the planting density increased. No differences were observed on yield per hectare between the tested systems. The Drilling trees produced significantly heavier and larger fruit than the trees trained to the V-Güttingen system.

Effect of Textured Dentated Surfaces on 30KhGSA Steel Damage and Life at Fatigue, Fretting Fatigue, and Fretting

Machines and constructions are noted to contain components, units, and assemblies, which are joined together, forming a large number of contacting pairs. At operating loads, the latter become sources of material damage as a result of fretting fatigue and fretting wear. The safety and long-term operation of those items would require studies on the nature of these processes and search for the methods of reducing their intensity. Investigation results for the effect of textured surfaces in the form of a dent (recess) network and electric-spark VK8 alloy embedding over 30KhGSA steel specimen surfaces on fatigue, fretting fatigue, and fretting wear characteristics are presented. The dent network is formed by plastic indentation using a specially developed device. This process initiates residual tensile stresses. Their optimization was carried out with computation-experimental correlation between the geometrical ratios of dent network parameters (spacing between dent rows, in-row spacing, dent depth). Discrete VK8 alloy-embedded surfaces were generated with the electric-spark method, providing optimum process parameters. Textured surfaces reduce fatigue and fretting fatigue resistance, while enhancing the fretting wear one in comparison with smooth surfaces. Additional treatment of the textured dentated surface with the ion-plasma thermocyclic nitriding method greatly increases the fatigue and fretting fatigue resistance of 30KhGSA steel. Electric-spark VK8 alloy embedding results in worse fatigue and fretting fatigue properties, which is determined by the surface formation technology and difference between embedded particle and base metal characteristics.

Vegetative and Reproductive Responses of Mature Cabernet Sauvignon Grapevines Converted from Spur Pruning to Cane Pruning at Five-Foot In-Row Vine Spacing

Summary Goals: Once established, vineyards are generally constrained by vine and row spacing and trellis configuration, which restricts how these variables can be modified. Regardless, such post-planting modifications may be desirable. This project chronicles vine performance following the conversion of seven-yr-old, cordon-trained, spur-pruned vines (“spur-pruned”) to head training and cane pruning (“cane-pruned”) with vines spaced 5 ft (1.5 m) apart in the row. While there are both pros and cons with either system, head training and cane pruning has an operational advantage in that less labor is expended on shoot-thinning because of retention of far fewer basal buds with cane-pruned vines. At issue, though, is a perception or reality that relatively wide in-row vine spacing (e.g., ≥4 or 5 ft) leads to uneven shoot development and nonuniform fruit ripening on long canes. We hypothesized that nonuniformity of shoot growth and development would lead to increased variability of fruit maturity at harvest with the conversion from spur pruning to cane pruning, with mature vines planted 5 ft (1.5 m) apart in the row. Key Findings: In comparison to spur pruning, the cane-pruned vines exhibited: (i) delayed budbreak and bloom; (ii) fewer, but more fruitful shoots; (iii) lower cane-pruning weights; and (iv) similar canopy architecture, primary fruit chemistry at harvest, and uniformity of pruned cane weights. Impact and Significance: Although we hypothesized that a 5 ft (1.5 m) in-row vine spacing might lead to nonuniform shoot development and fruit ripening on bilateral canes, this proved not to be the case. Although there was variation in components of yield for cane-pruned vines compared to spur-pruned vines, fruit maturity indexed as soluble solids concentration was similar between the two systems in the four seasons after conversion. While spur pruning has some advantage from the standpoint of reduced or eliminated time to tie canes following dormant pruning, the disadvantage, at least with Cabernet Sauvignon, as used here, is the propensity of cordon training to produce abundant basal shoots, which add excess crop and canopy density or additional labor to remove those shoots. A closer in-row spacing might be advised for cane pruning in new vineyards; however, it is possible to effectively convert spur-pruned vines back to cane pruning even for mature vines spaced 5 ft (1.5 m) apart in the row should that conversion be desired for labor savings, anticipated fruit quality improvements, or other reasons.

Efficacy of Seed Aging and Gibberellin Treatments for Manipulating Apical Dominance, Tuber Set and Size Distribution of cv. Shepody

The cultivar Shepody has excellent early processing qualities and produces above average tuber yields but sets relatively few tubers that often become excessively large relative to market demand. Optimizing tuber set and size of Shepody for seed and frozen processing markets currently entails adjusting in-row spacing and vine kill date. However, arresting tuber growth by vine killing for size control sacrifices yield potential. Aging seed by storing at 12, 22, and 32°C for 80-, 450-, and 900-degree days, or gibberellin (GA) treatments, were evaluated as more direct approaches for modulating stem number (apical dominance), tuber set, and size distribution relationships. Shepody proved to be inherently resistant to high temperature-induced age-priming treatments. In contrast to other cultivars studied previously, age-priming Shepody seed during storage had no effect on plant emergence and the resulting increases in stem number, tuber set, and associated decreases in average tuber weight were marginal. By contrast, GA applied as seed dip or spray effectively hastened plant emergence, reduced apical dominance, increased tuber set, and decreased average tuber size. The magnitude of these GA-induced effects depended on concentration and application technique (seed dip versus spray). For frozen processing, GA applied as a seed dip at 1 mg L-1 added an additional tuber per plant and decreased average tuber size by 15% without affecting U.S. No. 1 tuber yields and gross returns; however, 2 and 3 mg L-1 GA decreased U.S. No. 1 tuber yields and crop value by an average of 16 and 14%, respectively. Spray applications of 2–6 mg L-1 GA also reduced U.S. No. 1 tuber yield and frozen processing value. Conversely, the increase in tuber set (1.5 tubers plant-1) and associated 25% reduction in average tuber weight induced by 2 mg L-1 GA applied as either dip or spray increased gross crop values on a seed contract by 25 and 38%, respectively. The differential efficacies of dip versus spray applications of GA on tuber set and size distribution were likely attributable to differences in GA deposition on the seed. Applying low concentrations of GA to cut seed of Shepody as either a dip (1–2 mg L-1) or spray (2 mg L-1) effectively modulated tuber set and size to significantly increase gross returns for seed, and to better satisfy the needs of processors for more moderate size tubers.

Development and evaluation of a low-cost precision seeding control system for a corn drill

Precision seeding requires that the corn drill drop seeds into the soil by a specific in-row spacing while its travelling speed fluctuates due to unevenness of the field ground. This paper presents a low-cost precision seeding control system for a conventional corn drill with mechanical metering devices of finger-pickup type. A median filtering method was implemented in the control system to process measurements from a rotary encoder in order to acquire stable values of the corn drill travelling speed. The metering unit was driven by an electric motor controlled by the metering ECU according to the actual travelling speed and the desired in-row spacing in real-time. A user interface was programmed to communicate with ECUs for configuring parameters and displaying operating information during working. The newly-developed precision seeding control system was first calibrated in terms of speed measurement and control for two ECUs. Experiments were conducted on a seeding test platform in the laboratory for evaluating its accuracy in dropping seeds by giving different in-row spacing under different travelling speeds of the conveyor sticky belt. Results showed that the average spacing error was less than 2 cm and the maximum RMS error was 0.78 cm for all spacing values including 25 cm, 30 cm and 35 cm under the travelling speed of 1.0-8.0 km/h. These indicated that the low-cost precision seeding control system worked in a both accurate and stable way. Keywords: precision seeding, corn drill, control system, travelling speed, in-row spacing DOI: 10.25165/j.ijabe.20181105.3369 Citation: Yin X, Noguchi N, Yang T X, Jin C Q. Development and evaluation of a low-cost precision seeding control system for a corn drill. Int J Agric & Biol Eng, 2018; 11(5): 95–99.