Plant Row Spacing Research Articles

Effects of plant population and row spacing on grain yield of aerial-sown and drill-sown rice

Objective guidelines about plant population are essential to ensure that yield potential of rice grain is not compromised. Drill-sowing of rice is increasing in popularity in many rice-growing regions of the world in response to a requirement for increased water productivity, but little information is available on row-spacing widths required to maximise grain yield potential. This research investigated the impacts of plant population on grain yield and yield components for aerial- and drill-sown rice, and the effects of row-spacing width for drill-sown rice grown in a temperate environment. Ten aerial-sown and five drill-sown experiments were conducted in south-eastern Australia over three seasons using four semi-dwarf rice varieties. Plant populations ranged from 7 to 396 plants m–2. Plant populations as low as 30 plants m–2 were able to achieve grain yields >12 t ha–1 but only when the plants were uniformly distributed. At a population of ~100 plants m–2, the impact of plant-stand distribution was negligible. Grain yield was maintained across a large range of plant populations, mainly through compensatory effects of more tillers per plant and more grains per panicle at lower plant populations. For aerial-sown rice, maximum grain yield (up to 14.9 t ha–1) was always achieved with a minimum plant population of 100 plants m–2, and likewise for drill-sown rice provided the row spacing was ≤27 cm. At equivalent plant populations, 36-cm row spacing produced lower grain yield than narrower row spacings. When large gaps existed between plants within the rows, neighbouring plants could not compensate for the gap at the wider 36-cm row spacing, and grain yield was reduced. A practical optimal plant population of 100–200 plants m–2 was found to be suitable for the semi-dwarf varieties used in this study for both aerial- and drill-sowing methods.

Automatic Detection of Plant Rows for a Transplanter in Paddy Field Using Faster R-CNN

Uniform plant row spacing in a paddy field is a critical requirement for rice seedling transplanting, as it affects subsequent field management and the crop yield. However, current transplanters are not able to meet this requirement due to the lack of accurate navigation systems. In this study, a plant row detection algorithm was developed to serve as a navigation system of a rice transplanter. The algorithm was based on the convolutional neural network (CNN) to identify and locate rice seedlings from field images. The agglomerative hierarchical clustering (AHC) was used to group rice seedlings into seedling rows which were then used to determine the navigation parameters. The accuracies of the navigation parameters were evaluated using test images. Results showed that the CNN-based algorithm successfully detected rice seedlings from field images and generated a reference line which was used to determine navigation parameters (lateral distance and travel angle). Compared with mean absolute errors (MAE) test results, the CNN-based algorithm resulted in a deviation of 8.5 mm for the lateral distance and 0.50° for the travel angle, over the six intra-row seedling spacings tested. Relative to the test results, the CNN-based algorithm had 62% lower error for the lateral distance and 57% lower error for the travel angle when compared to a classical algorithm. These results demonstrated that the proposed algorithm had reasonably good accuracy and can be used for the rice transplanter navigation in real-time.

Planting Dates, Rates, and Methods of Agronomic Crops

Document (table) about planting dates, seeding rates and row spacing for field and forage crops that are sexually propagated. Information for Florida that considers factors as climate and weather conditions; fertility, moisture-holding capacity, temperature, and moisture content of the soil; depth to the water table; size and germination of the seed; plant size and growth habit; growing season and water requirements of the crop; and the habits of insects, disease, and other pests.

Effects of planting configuration and row spacing on growth and production of potato under mulched condition in Dadeldhura, Nepal

An experiment was conducted at the research site of Dadeldhura, Nepal in 2019 to identify optimum plant spacing for potato under mulched condition. Three levels of inter row spacing; 60 cm with single row per bed (1RB), 45 cm with double row per bed (2RB) and 30 cm with triple row per bed (3RB) and intra row spacing (20, 30 and 40 cm) were laid out in factorial randomized complete block design with three replications. Results showed that there was significant difference (p<0.05) for all parameters except on days to 50% germination, 90% flowering, 50% maturity and on main stem number and graded large sized tuber number and it's weight. Growth parameters namely canopy, leaf number and leaf area were significantly higher (p<0.05) in 60 cm (1RB) ×30 cm spacing. Plant height and leaf area index was significantly higher (p<0.05) in 60 cm (1RB) × 20 cm and 30(3RB) ×20 cm spacing respectively. Total number of tubers m-2 , weight of tubers m-2, weight of marketable tubers m-2, harvest index, number of small sized tuber m-2 ,weight of small sized tubers m-2 and weight of medium sized tubers m-2 were found to be 56.24%,39.79%, 47.98%,4.41%,90.56%, 113.23% and 70.15% significantly higher (p<0.05) in 30 cm (3RB) compared to 60 cm on (1RB) inter row spacing respectively and 59.72%, 61.15%, 58.30%, 4.41%, 114.90%, 137.31%, 55.39% higher in 20cm compared to 40 cm intra row spacing. Interaction effect was significant (p<0.05) in marketable tuber number and medium sized tuber number in which the average highest number of marketable tubers (134.44) and medium sized tubers (121.08) was found in 30(3RB) ×20 cm spacing which was 165.95% and 235.03% significantly higher compared to 60×40 cm spacing respectively. So, this study showed that 30(3RB) ×20 cm spacing would be best spacing combination under mulched condition.

Growth and Yield Responses of Curry Plant (Murraya koenigii) to Plant Row Spacing in an Utisol

Curry plant (Murraya koenigii) is one of the most important vegetable spices crops use for food, spice, medicinal and industrial purposes in Nigeria. However, curry plant production in commercial scale in Nigeria is highly constrained by several factors: it is not cultivated in regular farming system mainly due to lack of planting materials and improper plant spacing of this crop among others.
 Therefore, field experiments were conducted to determine the effect of different levels of plant row spacing on growth and yield of Curry plant (Murraya koenigii) in Cross River University of Technology, Teaching and Research farm, Department of Agronomy, Obubra, Cross River state, Nigeria in 2017 and 2018 cropping seasons. The experimental design was a randomized complete block design. Treatments were nine plant row spacing (70 x 50 cm, 70 x 70 cm, 80 x 40 cm, 80x60 cm, 90 x 30 cm, 100 x 50 cm, 100 x 70 cm, 100 x100 cm and 100 x130 cm) inter and intra row respectively with four replications. Results showed that plant row spacing have significantly affect the growth and yield of Curry plant. Closer plant row spacing of 70 x 50 cm significantly promoted the tallest plant height and highest leaf area inde x values of curry plant. Fresh and dry leaf yield on per hectare basis were significantly higher in closer plant row spacing than wider row spacing. The highest fresh and dry leaves yield per hectare at 20 weeks after planting (WAP) of 0.9742t/ha and 0.9871t/ha were obtained in closer row spacing of 70 x 50 cm in 2017 and 2018 cropping seasons respectively .
 The number of leaves and branches per plant and their fresh leaf yield and dry matter of plant fractions were higher in wider plant row spacing plots. The wide plant row spacing of 100 x 130 cm produced the highest fresh leaf yield per plant of 88.54 g in 2017 and 83.46 g in 2018 cropping seasons. Based on this result farmers are advised to cultivate Curry plant (Murraya koenigii) using the plant row spacing of 70 x 50 or 80 x 60 cm for optimum growth and yield per hectare of the crop under the utisoil condition.

Categorization of Plant Sapling using Deep Learning

According to the latest research, the current increment of the food production will not be able to satisfy the market due to the lack of farmers, and land areas with limited resources. Weeds are grown along with the plant seedlings, The Amount of water and fertilizers needed for the plant seedlings, Crop placement, and row spacing, are being the Major problems. The usage of deep learning using digital image processing could be an efficient way to overcome these problems. Deep Learning is based on Data Representations, Artificial and Neural networks. Plant species can be recognized using RGB images especially in the problem of weed detection. The resources and the row spacing needed for the seedlings can be fulfilled by recognizing the image with the preloaded datasets of the seedling.

A Rubber-Tapping Robot Forest Navigation and Information Collection System Based on 2D LiDAR and a Gyroscope.

Natural rubber is widely used in human life because of its excellent quality. At present, manual tapping is still the main way to obtain natural rubber. There is a sore need for intelligent tapping devices in the tapping industry, and the autonomous navigation technique is of great importance to make rubber-tapping devices intelligent. To realize the autonomous navigation of the intelligent rubber-tapping platform and to collect information on a rubber forest, the sparse point cloud data of tree trunks are extracted by the low-cost LiDAR and a gyroscope through the clustering method. The point cloud is fitted into circles by the Gauss–Newton method to obtain the center point of each tree. Then, these center points are threaded through the Least Squares method to obtain the straight line, which is regarded as the navigation path of the robot in this forest. Moreover, the Extended Kalman Filter (EKF) algorithm is adopted to obtain the robot’s position. In a forest with different row spacings and plant spacings, the heading error and lateral error of this robot are analyzed and a Fuzzy Controller is applied for the following activities: walking along one row with a fixed lateral distance, stopping at fixed points, turning from one row into another, and collecting information on plant spacing, row spacing, and trees’ diameters. Then, according to the collected information, each tree’s position is calculated, and the geometric feature map is constructed. In a forest with different row spacings and plant spacings, three repeated tests have been carried out at an initial speed of 0.3 m/s. The results show that the Root Mean Square (RMS) lateral errors are less than 10.32 cm, which shows that the proposed navigation method provides great path tracking. The fixed-point stopping range of the robot can meet the requirements for automatic rubber tapping of the mechanical arm, and the average stopping error is 12.08 cm. In the geometric feature map constructed by collecting information, the RMS radius errors are less than 0.66 cm, and the RMS plant spacing errors are less than 11.31 cm. These results show that the method for collecting information and constructing a map recursively in the process of navigation proposed in the paper provides a solution for forest information collection. The method provides a low-cost, real-time, and stable solution for forest navigation of automatic rubber tapping equipment, and the collected information not only assists the automatic tapping equipment to plan the tapping path, but also provides a basis for the informationization and precise management of a rubber plantation.

DENSIDADE POPULACIONAL, ESPAÇAMENTO E ADUBAÇÃO NITROGENADA NA SEMEADURA DE MILHO DE SEGUNDA SAFRA

A adequada distribuição das plantas e a adubação nitrogenada são práticas de manejo que afetam a produtividade do milho. Para o cultivo de milho segunda safra são necessárias informações quanto à resposta do arranjo das plantas à adubação nitrogenada. Sendo assim, o objetivo desse trabalho foi avaliar a interação entre densidade populacional, espaçamento entrelinhas e aplicação de nitrogênio (N) em semeadura na cultura do milho de segunda safra, cultivado em sistema de semeadura direta. O delineamento experimental empregado foi de blocos ao acaso, dispostos em parcelas subsubdivididas, com quatro repetições. Nas parcelas foram alocadas as densidades populacionais (60.000 e 75.000 plantas ha-1); nas subparcelas os três espaçamentos entrelinhas (0,40; 0,60 e 0,80 m) e nas subsubparcelas foram aplicadas quatro doses de N (20, 35, 50 e 65 kg ha-1) em semeadura. A adubação de cobertura foi realizada aplicando-se 100 kg ha-1 de N para todos os tratamentos na forma de ureia. Independentemente da dose de N, a densidade populacional de 60.000 plantas ha-1 e o espaçamento entrelinhas de 0,40 m proporcionaram maior produtividade de grãos de milho segunda safra. Maior número de grãos/espiga, número de fileiras/espiga, comprimento de espiga, massa de cem grãos e produtividade de grãos de milho segunda safra são verificados na dose de 65 kg ha-1 de N na semeadura.

Influence of Plant Densities on Some Yield Elements in Several Local and Foreign Soybean Cultivars in Transylvania Plain Conditions

Soybean can play an important role in securing the European protein resources. Transylvania Plain is a very favourable area for soybean crop. To optimise the crop management in these conditions, thirteen soybean cultivars (9 created at Agricultural Research and Development Station Turda and 4 of foreign origin) were studied with different plant densities and row spacing, in the specific environment of Transylvanian Plain. The yield increased by increasing the plant density up to 60 germinating seeds m-2, after which yield declined at the highest plant density. 60 g.s. m-2 plant population recorded the highest positive significant differences (approximately 10%), as compared to the average of all tested plant densities. The distance of 25 cm between rows produced a significantly higher yield as compared with the average of the trial. The climatic conditions influenced very significantly the yield variation (55.95%) while the genotypes, plant populations, and distances between rows had a statistically significantly lower influence (8.72%, 4.42% and 1.57%) compared to the effect of climatic conditions. The interaction between genotype and plant density contributed significantly (2.26%) to grain yield per unit area, while the interaction between plant density and row spacing had a statistically not significant effect of 1.09%).

Development and Field Test of an Autonomous Strawberry Plug Seeding Transplanter for Use in Elevated Cultivation

Abstract. Transplanting seedlings is one of the most important but labor-intensive operations in strawberry cultivation. However, oversized strawberry seedlings, the planting environment of elevated cultivation facilities and the requirement of positioning the arched back outward are unique challenges compared with current transplanters for other plants. First, we investigated the working environment and goal of the transplanter. In this research, a new system was proposed that is completely different from existing transplanters. The main components, including the autonomous vehicle navigated with an arc array of photoelectric switches, the pneumatic rotary dual-gripper unit, the dual-hole punching unit, the grip-punch coupled transportation unit, and the easy plug-feeding unit, were developed. Then, the structure and basic control logic of the control system was introduced, and an autonomous control mode with minimal manual intervention was described. In field tests, it was found that the prototype achieved the autonomous transplantation of oversized strawberry seedlings into elevated facilities, ensuring the proper orientation of the arched back. The overall success rate and speed reached 95.3% and 1047.8 plants/h, respectively, and the coefficients of variation of plant distance, row spacing, and row straightness were 4.67%, 6.55% and 5.77%, respectively. The transplanter developed here has good application prospects to replace manual operation. Keywords: Autonomous, Elevated cultivation, Strawberry, Seedling, Transplanter.

Yield response to plant density, row spacing and raised beds in low latitude spring wheat with ample soil resources: An update

This paper reviews the results of published and unpublished experiments over 30 years looking at the effect on yield of planting density and row spacing, and of raised bed planting, of modern irrigated short wheat cultivars under the favourable climatic conditions of northwest Mexico. With optimum planting dates (mid Nov. to mid Dec.), regardless of row spacing, wheat yield was remarkably insensitive to planting density within the range normally studied (80–400 plants/m2). However yield was sensitive to row spacing: the most sensitive cultivars (erect dwarf cultivars) lost yield at spacing 30 cm and greater, while the least sensitive (some taller vigorous semidwarf cultivars) tolerated spacing up to at least 50cm without yield loss. Yield sensitivity to wide spacing was unaffected by density but varied between years, being less in favourable cooler years, and was markedly greater with later plantings (Jan.). The response to yield on narrow raised beds (2–3 rows per bed, 75–90 cm between bed centres), which have many agronomic advantages, could be explained by the aforementioned yield responses to spacing, in this case the furrow gap or distance between rows on adjacent beds being critical. Yield testing with a furrow gap of 44–50 cm appeared to select cultivars more suited to this system, but it wasn’t clear whether such cultivars represented the best option under normal 20 cm row spacing in the absence of raised beds. When testing was extended to very low plant densities, yield was remarkably insensitive (maximum yield often achieved with only 16/m2), provided the planting date was normal and the planting arrangement did not deviate greatly from a square grid, with the honeycomb design giving an additional small yield advantage.These yield responses reflect the great plasticity in wheat imparted especially by tillering, and appear to be reasonably well explained by the notion that maximum yield requires close to full light interception no later than just before flag leaf emergence, being the onset of dry weight accumulation in growing spikes. Greater leaf greenness and probably higher radiation use efficiency with very low densities (and wide gaps), and associated delays in 50% flowering, may also assist in compensation for gaps. In contrast to much conventional wisdom, it is suggested that a worthwhile breeding objective would be selection for high per spaced-plant yield, with a view to achieving normal (or better) commercial yields at very low plant densities (< 20/m2), thereby opening up opportunities for new breeding and agronomic strategies in this era of precision cropping.

The response of corn (Zea mays L.) cultivars to row spacing under weed interference condition

This study was carried out in order to study the response of corn cultivars to row spacing and weed interference at the Research Farm of Agricultural and Natural Resources Faculty, Razi University, Kermanshah, Iran in 2011. The experiment was a split block factorial based on a randomized complete block design with three replications. Factors consisted of three corn cultivars ('KSC 704', 'Simon' and 'Maxima') and three plant row spacings (45, 60 and 75 cm) under weeded and un-weeded conditions for all of the growing season. Results indicated that for all three corn cultivars, the highest weed dry mass occurred in the row spacing of 75 cm. Weed interference throughout the growing season reduced corn grain yield by 20 %. This condition also significantly decreased corn yield components except the 100-seed mass. Increasing plant row spacing increased weed density, while decreased corn yield by 16.5 %. Corn cultivars were significantly different in terms of the number of seed per ear and 100-seed mass, as 'KSC 704' and 'Simon' showed the highest values for these yield components, respectively. However, the number of ear per plant and grain yield were not significantly different between the corn cultivars under study.

Exploring agronomic strategies to improve oat productivity and control weeds: leaf type, row spacing, and planting density

The trade-off between crop production and weed control is a fundamental scientific issue, as it is frequently influenced by individual crop competitive ability, population density, and planting pattern. A 2 yr field study was conducted to examine the relationship between planting density and row spacing, using two contrasting oat varieties. On average, high planting density (480 plants m−2) reduced weed biomass at oat maturity by 59% in 2012 and by 56% in 2013, when compared with a low density (120 plants m−2). The droopy-leaf variety suppressed weed biomass by up to 69% and weed density up to 72%, compared with the erect-leaf variety. In a drier year, the greatest grain yield was achieved with the droopy-leaf variety under the intermediate density, while in 2013, the erect-leaf variety under the high density had similar yield to the droopy-leaf variety at the intermediate density. A general trend was that increasing plant density suppressed weed infestation, and promoted crop biomass and yield. The droopy-leaf variety exhibited a strong competitive ability under the intermediate planting density, while the erect-leaf variety had a strong competitive ability under the high density. Taken together, there was a complex variety-by-environment interaction to achieve the balance between crop production and weed suppression, which was mediated by growing-season conditions.

Plant Population and Maize Grain Yield: A Global Systematic Review of Rainfed Trials

Maize (Zea mays L.) productivity has increased globally as a result of improved genetics and agronomic practices. Plant population and row spacing are two key agronomic factors known to have a strong influence on maize grain yield. A systematic review was conducted to investigate the effects of plant population on maize grain yield, differentiating between rainfall regions, N input, and soil tillage system (conventional tillage [CT] and no‐tillage [NT]). Data were extracted from 64 peer‐reviewed articles reporting on rainfed field trials, representing 13 countries and 127 trial locations. In arid environments, maize grain yield was low (mean maize grain yield = 2448 kg ha−1) across all plant populations with no clear response to plant population. Variation in maize grain yield was high in semiarid environments where the polynomial regression (p &lt; 0.001, n = 951) had a maximum point at ∼140,000 plants ha−1, which reflected a maize grain yield of 9000 kg ha−1. In subhumid environments, maize grain yield had a positive response to plant population (p &lt; 0.001). Maize grain yield increased for both CT and NT systems as plant population increased. In high‐N‐input (r2 = 0.19, p &lt; 0.001, n = 2 018) production systems, the response of plant population to applied N was weaker than in medium‐N‐input (r2 = 0.49, p &lt; 0.001, n = 680) systems. There exists a need for more metadata to be analyzed to provide improved recommendations for optimizing plant populations across different climatic conditions and rainfed maize production systems. Overall, the importance of optimizing plant population to local environmental conditions and farming systems is illustrated.

Practical aspects of grass forage seed production and quality with particular reference to planting row spacing and nitrogen fertilization in tropical regions: A review

The poor seed yield from some pasture grasses may result from a number of causes, such as the choice of site production, low soil fertility, inappropriate sowing rate, inadequate crop management practices particularly plant density, fertilizer input, poor seed recovery, etc. Compared with sowings of general plant use, seed crops warrant more care and expense during the establishment phase. Seedbeds should be prepared more thoroughly and the seed sown more precisely using adequate seeding rates. The effect of row spacing on the one hand and nitrogen level application on the other hand, have variable effect on grass seed production and there are a conflicting report in some cases depending on species, management practices and environmental conditions, and therefore a case-by-case study for each species and environment is important. In general, seed growers had better to sown seed in row than broadcasting and row spacing of 50-80 cm can be recommended for seed production depending on grass species or cultivars. The selection of optimal production areas depends on soil fertility, the photoperiod and temperature which can interact with rainfall and humidity of the site. The optimum sowing depths was 0-30 mm with some species and cultivars emerging from greater depths than others. With some exceptions, larger seeds were generally able to germinate successfully from greater depths. It was reported that seeds of Brachiaria brizantha and Panicum maximum established better when covered by 20-50 mm. Generally, applying fertilizer nitrogen to seed crops has implications for yield component dynamics such as tiller increasing, number of fertile tillers, floret per spikelet, and seed per head and ultimately increases seed yield and quality. Amounts of nitrogen fertilizer required will depend on species, soil type and rainfall. More often, 100-250 kg of nitrogen per ha and crop and rate more than 300 kg N/ha caused reduction in seed yield by severe plant lodging. For optimum time for nitrogen application, it can be recommended to growers to apply nitrogen in the period from vegetative to spikelet initiation.Keywords: Planting density, sowing, fertilization, seed yield, quality, tropical areas.

Effect of different lateral spacings on yield and quality attributes of drip-irrigated sweet corn

This study was conducted under Konya conditions to determine optimum lateral spacing for drip-irrigated sweet corn. For this purpose, three different drip irrigation systems were planned. Irrigation treatments consisted of two different lateral spacings (0.70 m and 1.40 m) and two different plant row spacings (standart 0.70 m and one narrow one wide row spacing, 45-95-45 cm). Effects of different drip irrigation systems on sweet corn yield and quality attributes were investigated. In the calculation of irrigation water, the percentage of wetted area is taken as 75%.Different lateral arrangements had significant effects on yields. The greatest fresh cob yield and single cob weight was obtained from the drip irrigation system with a lateral line for each plant row. The differences in cob yields of the other two treatments (the ones with a lateral line for two plant rows) were not found to be significant.

Corn (Zea mays L.) Response to Hybrid, Row Spacing, and Plant Populations in the Blacklands of Central Texas

Field studies were conducted during the 2013 and 2014 growing seasons in central Texas near Taylor (30.5326o N; 97.4548o W) to determine the effect of hybrid, row spacing, and plant populations on corn growth and yield. Two corn hybrids (BH 8844 and BH 8900) were compared at 53,000, 62,000, and 71,000 plants ha-1 planted one row on a single bed or twin rows (spaced approximately 20 cm apart) on a single bed. Plant counts were taken 4 to 6 wk after planting while ear height measurements were taken approximately four wk prior to corn harvest. Crop yield was determined by harvesting all eight rows of each plot with a combine. Weights were adjusted to 12% moisture. Experimental design was a factorial arrangement using a randomized complete block design with corn hybrid (2), row spacing (2), and seeding rates (3) as factors. Data were analyzed using PROC GLM with SAS (SAS Institute, Inc., Cary, NC) and treatment means separated by Fisher's protected least significant difference test at P = 0.05. Plant height was not affected by plant populations or row spacing as only hybrid response was significant with BH 8900 being taller in both years. Row spacing affected ear height in one of two years with the twin row spacing having a taller ear placement in the dryer year. No differences were seen with ear placement with respect to plant populations. In the dry year, yield of BH 8844 decreased as plant populations increased; however, no differences were noted with BH 8900. In the wet year, the inverse was seen with increased yield with higher populations with both hybrids. The twin row system increased BH 8900 yield in 2013. In 2014, with BH 8844, the single row system outyielded twin row and no differences noted with BH 8900. The results were quite variable and this was due in part to rainfall events in the two years. Plant and ear height was influenced by hybrid while yield response was somewhat affected by population and row spacing. A hybrid x row width response was noted indicating that certain hybrids will respond to row spacing more than others.

The effects of vegetation distribution pattern on overland flow

AbstractSoil erosion is a major environmental problem. Vegetation, on the other hand, plays an important role in controlling soil erosion. The goal of the study is to examine the effects of the distribution pattern of vegetation on water flow. The vegetation parameters involved included the direction of plant rows, plant stem diameter and row spacing. To study how vegetation affects the flow of water on slopes, flume simulation experiments were conducted using three different plant row directions, three different plant diameters and three row spacing. Experimental slope is fixed, slope ratio of 1.0%. The hydraulic characteristics of the slope under the three vegetation distribution patterns are explored. The results showed that the pattern of vegetation distribution significantly affected the resistance of vegetation to water flow and pattern on this slope. When the angle (θ) between plant row and water flow directions decreased, the plant diameter (d) increased, or the row spacing (a × a) decreased, the Darcy–Weisbach resistance coefficient (f) for water flow became larger. Simultaneously, the Reynolds and Froude numbers (Re and Fr) both became smaller. In experimental procedure condition, the change rate of f, Re and Fr were analysed by linear regression, the θ decreased every 10°, the average increase rate of f was 6.6%, the average decrease rate of Re and Fr were 2.0 and 3.0%. The d increased every 0.001 m, the average increase rate of f was 41.6%, the average decrease rate of Re and Fr were 11.2 and 12.2%. The a × a decreased every 0.01 m, the average increase rate of f was 45.2%, the average decrease rate of Re and Fr were 11.7 and 10.7%. The flow depth h increased every 0.01 m, the average increase rate of f and Re were 13.6 and 25.2%, and the average decrease rate of Fr was 10.4%. The experimental procedure results will be valuable for not only revealing the hydraulic characteristics of flow over vegetation land, but also the optimisation of the distribution of vegetation on a slope.

Planting date and row spacing effects on the agronomic potential of sesame in the southeastern USA

ABSTRACTSesame (Sesamum indicum L.) is being considered for commercial production in the southeastern USA, but very little is known about its potential and the appropriate management practices required to achieve sustainable yield potential in the area. This study thus aims to determine the optimal planting date and row spacing for several sesame cultivars. Traits examined were yield, plant height, number of nodes on the main stem, number of branches, height to first capsule on the main stem, and number of plants per meter. A first trial investigated three planting dates in Citra, FL (May, June, and July); whereas a second one examined several row spacings at two locations: 19 and 38.1 cm in Citra; and 19, 38.1, and 76.2 cm in Live Oak, FL. The May planting date showed higher yields, number of nodes, and taller plants than the other dates. Accumulated air and soil growing degree days (GDDs), rainfall, and solar radiation values were calculated for each planting date in both years. Soil GDDs provided similar results to air GDDs; thus, either model would seem appropriate for predicting crop development in this region. Plant height, number of nodes with capsules, and number of branches were increased at wider row spacings in the Live Oak trials as compared with narrow rows. These two trials illustrated the potential of sesame for attaining economically sustainable yields in the southeastern USA, but further exploration and modeling of agronomic traits will be needed to reach the crop’s full yield potential in these regions.

Effect of Cup Size, Seed Characteristics and Angular Speed on the Performance of an Automatic Potato Planter under Laboratory Conditions

The seed metering mechanism is the most important unit of potato planters. Accuracy of row plant spacing depends on the ability of the seed metering mechanism. The ability of the seed metering mechanism is directly associated with the constructive and operational variables of the planter. This study was conducted to evaluate the effects of different cups sizes (C1<C2<C3), different seed sizes (25 to 45 and 45 to 65 mm), different shapes (oblong and spherical), and angular speeds (0.9, 2.04 and 3.18 rad s-1) on the seed metering mechanism in a full automatic potato planter. The cup, angular speed, seed size and shape have an important role on the efficiency of the seed metering mechanism. The seed spacing uniformity was determined including doubles and skips. The coefficient of variation (CV%) was used to determine the seed spacing uniformity. The values of CV% for cups were 29.24, 23.76 and 26.11% for C1, C2 and C3, respectively. C3 has the highest percent value of doubles and the lowest percent value of skips. The seed spacing uniformity of oblong potato seeds was better than that of spherical potato seeds. The percent value of doubles increased and percent value of skips decreased for oblong potato seeds, opposite to the spherical potato seeds. The seed size of 45-65 mm gave a better seed spacing uniformity than the other seed size. It was observed that the seed size of 25-45 mm had higher percent value of doubles. The seed spacing uniformity tended to increase as the angular speed reduced. The CV% values of angular speed were 22.83, 24.90 and 31.39% for 0.9, 2.04, 3.18 rad s-1, respectively. As the angular speed increased, percent value of doubles decreased and percent value of skips increased.