In-row Spacing Research Articles

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.

Planting Geometry Effects on the Growth and Yield of Dryland Cotton

The declining Ogallala Aquifer beneath the Southern High Plains may necessitate dryland crop production and cotton (Gossypium hirsutum L.) is a well-adapted and potentially profitable alternative crop. The limited growing season duration of the Texas Panhandle and southwestern Kansas, however, imposes significant production risk due to incomplete boll maturation. Emphasizing earlier boll production that is usually confined to sites on lower fruiting branches may reduce risk, but offsetting high planting densities are needed to maintain desirable lint yield. Our objectives were to quantify planting: 1) row width and 2) in-row spacing effects on growth, yield, and fiber quality of dryland cotton. Field tests of row widths from 0.25 to 0.76 m and plant densities with in-row spacing ranging from 0.075 to 0.15 m were conducted from 1999 to 2005 on a nearly level Pullman clay loam (fine, mixed, superactive, thermic Torrertic Paleustoll) managed in a wheat (Triticum aestivum L.), cotton, fallow (W-Ctn-F) rotation. To expand the basis of comparison, cotton growth and yields were simulated using GOSSYM and long-term (1958-2000) weather records from Bushland, TX, as input for all combinations of 0.38 or 0.76 m row widths and plant spacing of 0.075, 0.10 and 0.15 m. Experimental and computer simulated plant height and harvested boll number increased significantly with increased row spacing and, occasionally, in-row plant spacing. Modeled lint yield for 0.38 m rows decreased by approximately 50% compared with the 582 kg·ha-1 yield for conventional row spacing, which was practically duplicated by field observations in 2001 and 2004. Measured fiber quality occasionally improved with conventional row spacing over ultra-narrow rows, but was unaffected by plant spacing. Because narrow rows and frequent plant spacing did not improve lint yield or fiber quality of dryland cotton, we do not recommend this strategy to overcome a thermally limited growing season.

MECHANIZATION OF SUGAR CROPS TRANSPLANTING

The main aim of this research was study the factors affecting the mechanical transplanting of main sugar crops related to development a single row transplanter prototype to fit the conditions of the Egyptian agriculture. Sugar cane is planted once every four or five year, and use of the transplanter prototype in transplanting sugar beet crop increases the number of annual operating hours and reduces the machine operation costs. The field experiments of the transplanter were conducted at four forward speeds of (0.7, 0.9, 1.2 and 1.4 km/h) and included the energy required, actual field capacity, field efficiency, actual in-row spacing, and missing hills percentage. Final results show that the average lower actual seedlings spacing 41.5 and 20.6 cm at forward speed 0.7 km/h for theoretical seedlings spacing 40 cm (sugar cane) and 20 cm (sugar beet) respectively, lowest values of missed seedlings (1.28%) and (1.53%) at forward speed of 0.7 km/h for crops of sugar cane (λ=0.262) and sugar beet (λ=0.525), Maximum field efficiency of transplanter was 82% and 76% at forward speed 0.7 km/h crops in case of sugar beet and sugar cane respectively and the transplanting costs were 830 L.E. and 597 L.E. per feddan with forward speeds 0.7 km/h for sugar beet and sugar cane crops respectively.

Evaluating Soil Solarization for Weed Control and Strawberry (Fragariaxananassa) Yield in Annual Plasticulture Production

Field studies were initiated in the 2013-14 and 2014-15 growing seasons to evaluate the potential of soil solarization (SS) treatments for their efficacy on weed control and crop yields and to compare SS to 1,3-dichloropropene (1,3-D)+chloropicrin (Pic) fumigation. Each replicate was a bed with dimension 10.6 m long by 0.8 m wide on top. The center 4.6 m length of each bed, referred to as plots, was used for strawberry plug transplanting and data collection. Treatments included: i) 1,3-D+Pic (39% 1,3-dichloropropene+59.6% chloropicrin) that was shank-fumigated in beds at 157 kg ha−1and covered with VIF on August 30 in both seasons; ii) SS for a 6 wk duration initiated on August 15, 2013 and August 21, 2014 by covering the bed with 1 mil clear polyethylene tarp; iii) SS for a 4wk duration initiated on September 6, 2013 and September 3, 2014; iv) SS 4 wk treatment initiated September 6, 2013 and September 3, 2014 and replaced with black VIF on October 4, 2013 and October 1, 2014 and v) a nontreated control covered with black VIF on October 4, 2013 and October 1, 2014. In both seasons, following completion of the preplant treatments, ‘Chandler’ strawberry was planted in two rows at a 36 cm in-row spacing in plots during the first wk of October. Over both seasons, the 6 wk SS treatment consistently lowered the weed density compared to the nontreated control. Weed density in the 6wk SS treatment was not statistically different from the 4wk SS treatments in the 2013-14 growing season. In both seasons, crop yield in the 4 wk SS was significantly lower than other treatments.

Plant Spacing Implications for Grafted Grapevine I. Soil Characteristics, Root Growth, Dry Matter Partitioning, Dry Matter Composition and Soil Utilisation

Six plant spacings (3 x 3 m, 3 x 1,5 m, 2 x 2 m, 2 x 1 m, 1 x 1 m, 1 x 0,5 m) were evaluated for their effect on aboveground and subterranean growth, dry matter partitioning and dry matter composition of different plant parts of vertically trellised Vitis vinifera L. cv. Pinot noir vines grafted onto rootstock 99 Richter. The vines were pruned to six buds/m2 soil surface area and supplementary irrigated just after pea berry size and veraison stages. Root distribution was studied by using the profile wall method and by excavating the whole plant. Apparently higher bulk densities occurred in the top soil layers of closer spacings. In the case of fine ( < 0,5 mm), extension (0,5 • 2 mm) and permanent (2 - 5 mm) roots, closer spaced vines significantly compensated in terms of root number per profile wall area. Higher root densities occurred with closer spacing. Aboveground and subterranean growth of the closerspaced vines were reduced; a distinction between in-row spacings of 1,5 m and wider and those 1 m and narrower occurred. Aboveground and subterranean growth were positively related. The angle of root penetration and size of the root system increased with wider spacing. The spread of the root system was apparently not affected by either inter-row or in-row spacing. The majority of roots were located within the allocated in-row distance. Cane and root mass and total vine dry mass per m2 soil surface indicated optimum utilisation of soil volume for medium-spaced vines (2 x 2 m, 2 x 1 m). Evidently higher starch concentrations occurred in the cordons, trunks and roots of widerspaced vines. Roots contained the highest starch concentrations, followed by the trunk, cordon, canes and rootstock trunk. Starch contents of aboveground and subterranean plant parts were similar. The ratio of aboveground:subterranean starch content was, however, lower for closely spaced vines.

Seed Piece Spacing for Spring Chipping Potato Cultivars in Florida

The cost of seed accounts for nearly 10% of the estimated production cost of chipping potato (Solanum tuberosum) production in Florida. Optimizing seed piece spacing can reduce costs without affecting potato yield. This study evaluated the effects of seed piece spacing on yield, quality, and economic revenue of chipping potato production in north Florida. A field experiment was conduct during the spring of 2013, 2014, and 2016 in Hastings, FL, with a split-plot randomized complete block design. In-row seed piece spacings of 10, 15, 20 (industry standard), 25, and 30 cm were assigned as the main plot and S. tuberosum potato cultivars (Atlantic, Harley Blackwell, and Elkton) as the subplots. Marketable tuber yield ranged between 10.8 and 15.2 Mg·ha−1 in 2013, 10.1 and 12.8 Mg·ha−1 in 2014, and 9.9 and 19.7 Mg·ha−1 in 2016. Overall lower yields in 2013 were due to three freeze events early in the season. Widening seed piece spacing resulted in a linear decrease in total and marketable yield in 2013 and 2014. Conversely, seed piece spacings of 10 and 15 cm showed lower marketable yields in 2016. There was no interaction between in-row spacing and cultivar in any year tested. Cultivars performed variably across years for total and marketable yield and specific gravity. Tuber specific gravity was unaffected by seed piece spacing, except in 2013, when 25 and 30 cm resulted in slightly higher values. There was no significant difference in total and marketable yield between the industry standard seed piece spacing 20 and 25 cm in any year. In-row spacing of 25 cm in 2013 and 30 cm seed piece spacing in 2014 and 2016 provided the greatest economic return. Net revenue can be increased by adjusting the in-row seed piece spacing from the commercial standard of 20 to 25 cm, which reduces production cost without negatively impacting yields.

Inter- and Between-row Spacing on Yield and Quality of a Pumpkin Interspecific Hybrid

ABSTRACTPrevious research indicated that the pumpkin (Cucurbita moschata L.) interspecific hybrid ‘MO11 × P25’ had the most positive and negative heterosis for plant yield and plant length, respectively. Due to its negative heterosis for plant length it is possible to culture this plant at a higher plant density. Growers have two options when increasing plant populations per unit area; either within-row or between-row spacing can be decreased. The objective of this research was to determine the effect of altering plant population by varying between-row and in-row spacing on yield of pumpkin interspecific hybrid ‘MO11 × P25’ to increase yield by reducing vegetative growth and increasing reproductive. The interspecific hybrid ‘MO11 × P25’ was established at 1, 2, or 3 m between rows and 0.5, 0.75, or 1 m within rows. There were differences between inter- and between-row distances and their interaction on all characteristics except carotenoids content. Increasing interspecific hybrid ‘MO11 × P25’ plant population by varying both between-row and in-row spacing increased yield; the highest yield (98.4 t•ha−1) was with a spacing of 1 × 0.5 m.

Adensamento de plantio em pessegueiros ‘Chimarrita’

The average peach yield for Rio Grande do Sul State is only 9.8 t ha-1, which is the lowest among the main six Brazilian peach producing states. One of the factors that can contribute decisively to improve productivity is to increase planting density. This research aimed to study the technical feasibility to reduce in-row spacing for ‘Chimarrita’ peach, under edaphoclimatic conditions in Pelotas, Rio Grande do Sul State, Brazil. A non-irrigated experimental field orchard was established and five tree spacing were tested: 6.3 x 1.0 m (1,587 trees ha-1), 6.3 x 1.5 m (1,058 trees ha-1), 6.3 x 2.0 m (794 trees ha-1), 6.3 x 2.5 m (635 trees ha-1) and 6.3 x 3.0 m (529 trees ha-1), in randomized blocks with four repetitions. We concluded that the planting densities tested did not affect fruit weight, transversal and longitudinal fruit diameter, and also did not affect trunk diameter, trunk cross sectional area (TCSA) and yield efficiency. However, 6.3 x 1.0 m or 6.3 x 1.5 m spacing led to significant increases in accumulated yield in the first four years of production. The higher planting density in ‘Chimarrita’ peach presents technical feasibility at adaphoclimatic conditions of Pelotas-RS, Brazil, and we recommended 6.3 x 1.0 m or 6.3 x 1.5 m spacing.

Planting date and in-row plant spacing effects on growth and yield of cabbage under plastic mulch

Florida is ranked third in total cabbage production in the U.S. and it is traditionally grown on bare ground with subirrigation. The use of plastic mulch and drip irrigation is widespread for other vegetable crops and can enhance water and fertilizer use efficiency and yield. The objective of the study was to evaluate plant growth, yield and head quality traits of cabbage using three plant populations and four planting dates on a plastic mulch system. Cabbage was transplanted in mid September (SEP), mid October (OCT), early November (NOV), and early December (DEC) in the 2013–14 and 2014–15 growing seasons, spanning the entire planting season for commercial operations in northeast Florida. There was no interaction among planting dates and plant populations for total and marketable yields or biomass. For both seasons, the SEP and OCT plantings showed a faster growth rate than NOV and DEC during the first 70 days after transplanting; however, differences in total biomass accumulation were only seen in 2013–14. Biomass decreased quadratically in 2013–14 with an increase in in-row spacing. Average marketable yield for both years was 62.7, 60.5, 46.2, and 58.6Mgha−1 for SEP, OCT, NOV and DEC, respectively. As plant population decreased, marketable yield increased linearly in 2013–14 while no differences were seen in marketable yield among plant population treatments during 2014–15 season. Plant growth rate and yield were correlated to growing season average air temperature and solar radiation. The SEP, OCT and DEC planting dates benefited from more favorable weather conditions, while low air temperatures and reduced solar radiation had a negative effected on cabbage yield for the NOV planting.

Automated Thinning Increases Uniformity of In-row Spacing and Plant Size in Romaine Lettuce

The low availability and high cost of farm hand labor make automated thinners a faster and cheaper alternative to hand thinning in lettuce (Lactuca sativa). However, the effects of this new technology on the uniformity of plant spacing and size as well as crop yield are not proven. Three experiments were conducted in commercial romaine heart lettuce fields in 2013 and 2014 in Imperial Valley, CA, to compare the effects of automated thinning and hand thinning on uniformity of in-row spacing, plant size, and crop yield. Overhead images taken at 1 week after hand thinning indicate that thinning 8 to 11 days earlier by automated thinners did not affect plant size compared with the hand thinning treatment. However, lettuce plants in the automated thinning treatment were larger than plants in the hand thinning treatment 2 to 3 weeks after hand thinning. Automated thinners increased the uniformity of in-row spacing, increased the percentage of plants with the desired in-row spacing of 24 to 32 cm, and almost completely removed plants with an undesirable in-row spacing of 4 to 20 cm. As a result, individual lettuce plant weight and heart weight from the automated thinning plots was significantly greater and plants were more uniform compared with the hand thinned plants. Despite increases in lettuce plant size and uniformity in all three experiments, yield benefits of automated thinning were only significant in one of the three experiments due to larger plant populations resulting from hand thinning. This study suggests that automated thinning increases lettuce plant size and uniformity and makes it possible for growers to increase plant population and crop yield by optimizing in-row spacing.

Sweet potato production in a short-season area utilizing black plastic mulch: effects of cultivar, in-row plant spacing, and harvest date on yield parameters

The sweet potato (Ipomoea batatas (L.) Lam.) requires a long, hot growing season to attain good yields. In a cool climate, the use of black plastic mulch to heat the soil can improve growth but cultivars, plant spacing, and harvest date must be carefully selected to optimize yields and to attain market quality standards. In this two-year study in Quebec, Canada, two sweet potato cultivars (‘Georgia Jet’ and ‘Beauregard’) were grown at four in-row spacings (15, 30, 45, and 60 cm) and harvested at three dates (mid September, late September, and early October). Cumulative growing degree-days (GDD) with base temperatures of 10°C and 15.5°C were calculated for each harvest date. ‘Georgia Jet’ had higher total and marketable yields than ‘Beauregard’. In-row spacing had no effect on yields per hectare of ‘Beauregard’ and only affected ‘Georgia Jet’ in one year of the study. Average root weight of sweet potatoes, yields per plant, and number of roots per plant increased with wider spacing. Delaying harvest by one or two weeks had little effect on ‘Beauregard’ but increased yields of ‘Georgia Jet’. GDD may be a useful predictor of optimum harvest date but a lower base temperature used to calculate GDD may be desirable with ‘Georgia Jet’ as its yields continued to increase even when growing under cool conditions of late September and early October.

Optimizing Tuber Set and Size Distribution for Potato Seed (Solanum tuberosum L.) Expressing Varying Degrees of Apical Dominance

Plant emergence, apical dominance, tuber set, and size are affected by the physiological age of seed tubers, which can substantially impact overall crop value. This study investigated the efficacy of seed spacing (15, 25, and 35 cm) and 1-naphthaleneacetic acid (NAA) seed treatments in altering these variables in cv. Ranger Russet to improve yield and tuber size distribution of seed expressing low (2.8 stems/seed piece) and high (4.8–5.4 stems/seed piece) apical dominance. Age primed, high-stem seed produced more tubers per plant and per ha than non-aged seed; however, tuber number per ha from both seed lots fell to the same extent with decreasing plant density. Importantly, tuber set per plant increased substantially more for the physiologically older, high-stem seed as plant spacing increased. Average tuber weight also increased with decreasing plant density but the response was greatest for the physiologically younger, low-stem seed. Regardless of seed age, marketable yields were comparable at 25- and 35-cm spacing. Tuber size distributions from the 2.8-stem seed shifted from oversize (>340-g) tubers to higher percentage 113–284-g tubers as spacing decreased from 35 to 15 cm. The 5.4-stem seed produced less undersize ( 284-g tubers when planted at 35-cm spacing. Adjusting in-row spacing relative to seed age and expected stem numbers improved tuber size distribution and value. However, because plants from older seed set more tubers in response to decreasing plant density than younger seed, average tuber weight and size distribution never matched the younger seed at any spacing. Restoration of apical dominance by treatment of seed with NAA was more effective in this regard. Depending on seed age, NAA delayed plant emergence (22–74 %) and decreased stem (24–38 %) and tuber numbers per plant (8–13 %). Stem numbers from age-primed seed fell from 4.8 to 3.0 as NAA concentration increased. Marketable yields were not affected by seed age but decreased slightly (7.3 %, P 284-g) tubers, resulting in a yield profile approaching that of the non-treated younger seed. Although seed spacing and NAA treatments are effective techniques for altering tuber size distribution to maximize crop value in relation to seed age and expected stem numbers, tuber age had a small but residual effect on productivity beyond that attributable to apical dominance.

Optimum Planting Configuration for High Population Plasticulture Grown Cabbage

Florida is a major fresh-market cabbage (Brassica oleracea L. var. capitata) producing state in the United States. The current cabbage production system relies on bare ground and subirrigation that requires a large volume of water to irrigate the crop. The bare ground system facilitates a maximum of 48,438 plant/ha, while there is a potential to increase plant population per area using plasticulture and drip irrigation. The objectives of this study were to determine the optimum cabbage plant population and plant arrangement that maximizes marketable yield per area for a high cabbage population plasticulture system. Cabbage was grown on 1.2-m-wide raised beds with black plastic mulch and drip irrigation. Plants were grown in either three or four rows with in-row plant spacings ranging from 15 to 35 cm and plant populations ranging from 41,518 to 129,167 plants/ha. Cabbage marketable yield increased as in-row spacing increased. Yields ranged from 19.7 to 69.7 Mg·ha−1. Marketable yield was not different between 3 and 4 rows for in-row spacings above 25 cm. The 15 and 20 cm in-row spacing produced significantly lower yields in the 4-row configuration as compared with the 3-row configuration in Fall and Winter 2011. Wider in-row spacings produced a greater percentage of heads of marketable size while reducing the percentage of small heads when compared with narrower in-row spacings. Mean head weight increased as in-row spacing increased and a 3- or 4-row configuration with an in-row spacing between 25 and 30 cm had consistently high yields in all three seasons compared with narrower in-row plant spacings. These results indicated that with a high population plasticulture system variable plant populations could be selected. In-row plant spacings between 30 and 35 cm may be beneficial for early plantings while a 25-cm spacing could be more productive for later plantings, especially when weather conditions are favorable.

Increasing In-Row Spacing Enhances Potato Virus Y and Potato Leafroll Virus Spread in Potato

For potato, variety, tuber size, and chip or fresh markets all play a role in deciding which in-row spacing is used. Aphids are attracted to wide row spacings and as plant densities decrease, aphid densities increase. Wide in-row spacing could render ineffective any pest management tactic that exploited aphid colonization behavior through habitat manipulation if it prevented adequate row closure and enhanced aphid landing rates. To understand this, we studied the effect 20.3, 30.5, 45.7, 68.5, and 101.6 cm in-row spacing treatments had on PVY and PLRV spread. PVY infection reached 14.8 % at 101.6 cm in-row spacings and was the lowest (5.9 %) at 20.3 cm spacings. PLRV infection was highest at 101.6 cm spacings (69.1 %) and lowest at 20.3 cm spacings (44.2 %). Optimal potato production occurs on in-row spacing of 25 to 30 cm. Based on our results, current potato cultural practices in relationship to row spacing are not enhancing virus spread.

English

A field experiment was conducted from November to March during the 2012 / 2013 planting season at Africa University farm, Mutare, Zimbabwe to evaluate the effects of plant spacing and different potato varieties on growth, yield and quality of potato (Solanum tuberosum L.). The experiment was designed as a randomized complete block design with 4 × 3 factorial arrangements of treatments. The first factor was plant spacing (in-row spacing); 20, 25, 30 and 35 cm. The second factor was varieties: BP1, KY20 and Mnandi. Very close spacing produced a high number of small sized tubers leading to reduced marketable yield. The highest stem count was observed at high plant densities, the lowest at low plant densities. At low density plantings, leaf number per plant was high and at high density plantings the leaf number was reduced across all varieties. BP1 and KY20 exhibited the highest specific gravity and Mnandi had the least. Results of the study suggest that a wider spacing of 90 by 35 cm can be advantageous for all the three varieties since all the varieties compensated for the additional spacing to produce the highest marketable yield yet with less seed thus reducing production cost. Also from the study, an in-row spacing of 25 cm can be used by seed producers since the highest number of medium sized tubers was obtained and this size is normally used as seed. Key words: Plant spacing, potato yield, potato quality, potato varieties.

Potential of cultivar and crop management to affect phytochemical content in winter-grown sprouting broccoli (Brassica oleraceaL. var.italica)

Variety and crop management strategies affect the content of bioactive compounds (phenolics, flavonoids and glucosinolates) in green broccoli (calabrese) types, which are cultivated during summer and autumn in temperate European climates. Sprouting broccoli types are morphologically distinct and are grown over the winter season and harvested until early spring. Thus they show considerable potential for development as an import substitution crop for growers and consumers during the 'hungry gap' of early spring. The present study investigated the effect of variety and management practices on phytochemical content in a range of sprouting broccoli varieties. Yields were significantly higher in white sprouting broccoli varieties. Levels of phenolics and flavonoids were in the range 81.64-297.65 and 16.95-104.80 mg 100 g⁻¹ fresh weight, respectively, depending on year and cultivar, and were highest in variety 'TZ 5052' in both years. In-row spacing did not affect flavonoid content. Phenolic and flavonoid content generally increased with increasing floret maturity and levels were high in edible portions of the crop. Crop wastes (leaf and flower) contained 145.9-239.3 and 21.5-116.6 mg 100 g⁻¹ fresh weight total phenolics and flavonoids, respectively, depending on cultivar, tissue and year. Climatic factors had a significant effect on phenolic and flavonoid content. Levels of total and some individual glucosinolates were higher in sprouting broccoli than in the green broccoli variety 'Ironman'. Levels of total phenolics, flavonoids and glucosinolates are higher in sprouting than green broccoli types. Sprouting broccoli represents an excellent source of dietary bioactive compounds.

Influence of Seed physical properties and speed on the external mechanical damage index and in-row spacing uniformity in an automatic potato planter

Patates dikim makinası patates verimi ve kalitesi üzerine çok önemli bir rol oynar. Bir patates dikim makinasının görevi yumruları düzenli aralıklarla toprağa yerleştirmektir. Bu çalışmada, tohum dağıtma düzeni dikey bir disk olan yeni bir patates dikim makinası kullanıldı. Patates dikim makinasının performansı sıra üzeri düzgünlük (varyasyon katsayısı (%CV), boşluk ve ikili atma) ve yumru yaralanma indeksi dikkate alınarak belirlendi. Denemeler tohum dağıtma düzeninin üç açısal hızında (1.56, 2.39 and 3,22 rad s -1 ), iki farklı patates çeşidi (Marfona and Agria) ve iki patates büyüklüğünde (<45 mm den küçük yumru ve >45 mm den büyük yumru) yürütüldü. Denemeden elde edilen sonuçlar patates dikim makinası performansı üzerine yumru fiziksel özelliklerinin ve hızın önemli derecede etkili olduğunu gösterdi. Elde edilen sonuçlar diğer araştırmacıların rapor ettikleri sonuçlar ile benzerlik gösteriyordu. Ortalamaları karşılaştırma testine göre (LSD testi, P=0.05), en yüksek varyasyon katsayısı 3.22 rad s -1 açısal hız için %26.80, Marfona çeşidi için %25.58 ve 45 mm den küçük yumrular için %26.27 idi. En yüksek yaralanma indeksi 3.22 rad s -1 açısal hız için 1.34, Agria çeşidi için 1.18 ve 45 mm den büyük yumrular için 1.23 idi

Development of Simple Bayesian Belief and Decision Networks as Interactive Visualization Tools for Determining Optimal In-row Spacing for ‘Beauregard’ Sweetpotato

A Bayesian belief network (BBN) model, which we named BxINROW/NET, was developed to represent the relationships among in-row spacing regimes, some agroclimatic variables known to influence storage root initiation, growing degree-days (GDDs) to harvest, and yield grades in ‘Beauregard’ sweetpotato grown in Louisiana. The model was developed from experimental data collected in a subset of years between 1990 and 2010 and assumed that soil moisture, weeds, and chemical injury were not limiting variables during the growing season. The BBN model error rates for storage root yields were 21%, 20%, and 13% for U.S. #1 (US1), canner, and jumbo grades, respectively, as estimated from repeated random partitioning of the modeling data set into training and testing partitions. In comparison, the error rates for a baseline logistic regression model were 56%, 54%, and 53% for US1, canner, and jumbo grades, respectively. The BBN model showed that GDDs to harvest (GDDH) as well as air and soil temperatures during the critical storage root initiation period [20 days after transplanting (DAT)] interacted with in-row spacing regimes to help determine the yield outcomes. Under a uniform irrigation management and minimum to intermediate GDDH (980 to 1495 GDDs), narrow (20 to 22 cm) to intermediate in-row spacing regimes (30 cm) were associated with higher probabilities (56% to 71% of cases) for attaining a high US1 yield (22 to 45 t·ha−1). These outcomes were associated with minimum to intermediate soil and air heat units 20 DAT, representing early to intermediate planting dates. Under similar conditions, wide in-row spacing treatments (38 to 40 cm) were associated with increased probabilities (100% of cases) for achieving a high yield of jumbo or oversized roots if GDDH (1495 to 1710 GDDs) was maximized. BxINROW/NET was also used as the foundation model to construct Bayesian decision networks (BDNs) for fresh market and processing scenarios. The BDNs were constructed by adding a value or gain node associated with each yield grade. Nodes representing price per box and stand deficiency were also added. These nodes allowed the prediction of estimated net return associated with a specific in-row regime given some agroclimatic variables and GDDH. As a result of its reliance on conditions observed in the study, BxINROW/NET is only applicable to a local Louisiana growing area. Further study is necessary to determine the model's applicability in other regions and growing conditions.

Potato Seed Piece Size, Spacing, and Seeding Rate Effects on Yield, Quality and Economic Return

It has been observed that potato producers often focus more on the quantity of potato seed pieces being planted per unit area than on seed piece size and placement within the row. This study compared the effects of seed quantity per unit area (Mg ha−1) or seed piece size and in-row spacing on potato yield and quality. Hand-cut certified seed of three potato cultivars (Alturas, Russet Norkotah, Ranger Russet) of three size classes (42, 64 or 85 g) were planted at in-row seed piece spacings of 20, 30 or 40 cm. Three of the treatments (42-g seed pieces planted at 20 cm, 64-g seed pieces planted at 30 cm, and 85-g seed pieces planted at 40 cm) resulted in equal weights of seed planted (2.28 Mg ha−1). Increasing seed piece size from 42 to 85 g resulted in higher total yield regardless of in-row spacing. U.S. No. 1 yield was increased only at the 40-cm in-row spacing when 42- and 85-g seed pieces were planted. Increasing seed piece spacing from 20 to 40 cm resulted in lower total and U.S. No. 1 yields at all three seed piece size treatments. However, equal seeding rates of 2.28 Mg ha−1 resulted in equal total and U.S. No. 1 yields. Altering seed piece size or in-row spacing had little effect on tuber yields in the 285–397-g size category. A fresh-pack economic gross returns analysis of Russet Norkotah based on tuber size distribution less seed costs resulted in higher gross returns per ha only for 85-g seed pieces planted at 40 cm compared with planting 42- or 64-g seed pieces at a the 40 cm. At an equal seeding rate of 2.28 Mg ha−1, paired t-tests indicated there were no differences in gross returns per ha. However, the effects of seed piece size and spacing on economic return will depend on cost of seed and the selling price of the harvested potatoes.

Narrow row spacing and high plant population to short height castor genotypes in two cropping seasons

Castor plant ( Ricinus communis L.) produces a very important oil for chemical and biofuel industries. However, doubts remain about what the best plant arrangement is to obtain the maximum yield of seeds and oil from short height castor genotypes cultivated in higher plant population. This study evaluated two castor genotypes (FCA-PB and IAC 2028) in 5 plant arrangements (row spacing × in-row spacing): 0.90 m × 0.44 m (traditional), 0.90 m × 0.20 m, 0.75 m × 0.24 m, 0.60 × 0.30 m, and 0.45 m × 0.40 m, in spring–summer and fall–winter cropping seasons in Botucatu, São Paulo State, southeastern Brazil. The traditional plant arrangement comprised an initial plant population of 25,000 plants ha −1, while the others comprised 55,000 plants ha −1. The IAC 2028 genotype presented the greatest plant height, first raceme insertion height, basal stem diameter, number of fruits per raceme and 100 seed weight; however, seed yield and seed oil content were equal between genotypes. Wider stems and higher number of racemes per plant and fruits per raceme were observed with a 0.90 m × 0.44 m plant arrangement, but due to the lowest plant population (25,000 plants ha −1) in this plant arrangement, the higher values of the yield components mentioned above did not result in higher yield. The higher plant population (55,000 plants ha −1) by narrower row spacings (0.45 or 0.60 m) combination produced a higher castor seed yield. The effect of plant arrangement was more intense in the spring–summer cropping season.