Sowing Density Research Articles

Developing Production Guidelines for Baby Leaf Hemp (Cannabis sativa L.) as an Edible Salad Green: Cultivar, Sowing Density and Seed Size

Scientific literature is lacking on cultural practices of baby leaf hemp production even though hemp (Cannabis sativa L.) is a widely grown crop for fiber and grain. The objective of this study was to develop a standard protocol to optimize yield and quality of baby leaf hemp production: cultivar screening, sowing density and seed size. Fresh weight (FW) and germination percentage was significantly affected by cultivars. Cultivars ‘Picolo’ and ‘X-59’ had a greater FW mainly due to greater germination percentage. In the sowing density experiment, ‘Ferimon’ and ‘Katani’ were evaluated at five seed densities, 0.65, 1.2, 1.75, 2.3 and 2.85 seeds·cm−2 (42 to 182 seeds per cell). The FW and FW per plant (FWPP) had a positive quadratic response and negative quadratic response, respectively. Regarding seed size, cultivars ‘Anka,’ ‘Ferimon’ and ‘Picolo’ had the largest percentage of seeds, 26% to 30%, within the medium width size between 3.18 and 3.37 mm. Using the largest sized seeds (3.77 mm) increased FW by 34%, 26% and 23% as compared to non-sorted ‘Anka’, ‘Ferimon’ and ‘Picolo’ seeds, respectively. Overall, a greater understanding of cultivar selection, sowing density and seed-size distribution can promote greater yield and quality of baby leaf hemp as an edible salad green.

SOIL PROTECTION BY USED OF COVER CROPS CONSORTIA AND SINGLE CULTIVATION

The no-till system has been growing over the years and for this system to be successful, it is essential to maintain permanent vegetation cover over the soil, an adequate crop rotation system with minimal overturning. A strategy for soil protection is to introduce species of cover crops in winter under single or intercropping. The objective was to evaluate the rate of soil cover by intercropping between black oats (Avena strigosa L.) and forage turnip (Raphanus sativus L.) at different sowing densities, as well as the isolated species in terms of soil protection under no-tillage. The study was conducted at the Federal Technological University of Paraná (UTFPR), campus Santa Helena, with a randomized block design, with five treatments and three repetitions. The treatments were: 100% black oats (BO); 100% forage turnip (FT); 75% BO + 25% FT; 50% BO + 50% FT and 25% BO + 75% FT. The cover crops were sown in May 2019. The percentage of soil cover from 21 to 91 days after sowing (DAS) was evaluated using the photographic method, with weekly collection of images in an area delimited by a metallic frame (25 m²), positioned on the ground at two fixed points per plot. The coverage rate quantification was estimated by overlaying a grid with 100 points of intersection over each image. The rate of soil cover by consortia and single crops did not show a statistically significant difference. To 49 days, consortia had coverage equal to or greater than 70%, while for single species, this percentage was reached at 56 DAS and 70 DAS, for BO and FT, respectively. All treatments showed high potential for soil protection and coverage rate from 70 DAS.

Biological features of formation of productivity of a new variety Hlukhivski 51

The dependence of sowing density, duration of interphase periods, intensity of plant growth in height by vegetation phases and signs of productivity of the new variety Hlukhivski 51 in comparison with the standard variety Hliana are emphasized. In contrast to the standard variety, the Hlukhivski 51 variety has a number of biological features of the genotype: longer interphase periods, plant growth intensity, fiber layer thickness and primary and secondary cell sizes, which ensures high productivity in terms of stem, fiber and long fiber yields. The high yield potential of the new variety is of great interest to producers of stem processing and fiber production.

Growth and productivity of Salvia officinalis L. under Mediterranean climatic conditions depends on biofertilizer, nitrogen fertilization, and sowing density

Salvia officinalis L. is an important medicinal herb of high soil and climatic adaptability and thus the main goal of the current study is to investigate the effect of mycorrhizae, the plant density and the nitrogen fertilization (using bio-fertilizers) on the yield and growth characteristics. For the purpose of the study, a field experiment was established at the Experimental Farm of the University of Thessaly, Velestino, in 2017, 2018 and 2019, respectively. The experimental design was a factorial split-split-plot design with Mico-plus being the main factor (Trt1: control, Trt2: mico-plus which contains non composed plant residues, 3% Glomus mosseae and Glomus intradices, 1 × 108UFC/g Bacillus spp, Pseudomonas spp., and Streptomyces spp., and 1 × 108UFC/g Trichoderma), plant density the sub-factor (P1: 10,000 and P2: 20,000 plants ha−1) and N-fertilization the sub-sub factor using bio-fertilizers (N1: 0, N2: 40, and N3: 80 kg N ha−1) with three replicates. Height, leaf area index and leaf yield were measured by samplings at the ideal collection stage (start of the flowering period). The use of mico-plus and nitrogen fertilization resulted in significantly higher yield. Furthermore, plant density had a negative effect on measured values, leading to reduced leaf yield and lower leaf area. The higher produced leaf yield and leaf area (7296 kg ha−1 and 4.47 leaf area index, respectively) were recorded in the third year for the treatment of the lower plant density with the higher N-dressing where mico-plus was used (MP1N3). Therefore, sage seems to be a promising perennial cultivation characterized by satisfactory yields under low inputs in similar soil-climatic environment, while the use of mico-plus should be taken into consideration, especially in the case of poor and abandoned lands.

Optimizing sowing density-based management decisions with different nitrogen rates on smallholder maize farms in Northern Nigeria

AbstractIn this study, the CERES-Maize model was calibrated and evaluated using data from 60 farmers’ fields across Sudan (SS) and Northern Guinea (NGS) Savannas of Nigeria in 2016 and 2017 rainy seasons. The trials consisted of 10 maize varieties sown at three different sowing densities (2.6, 5.3, and 6.6 plants m−2) across farmers’ field with contrasting agronomic and nutrient management histories. Model predictions in both years and locations were close to observed data for both calibration and evaluation exercises as evidenced by low normalized root mean square error (RMSE) (≤15%), high modified d-index (> 0.6), and high model efficiency (>0.45) values for the phenology, growth, and yield data across all varieties and agro-ecologies. In both years and locations and for both calibration and evaluation exercises, very good agreements were found between observed and model-simulated grain yields, number of days to physiological maturity, above-ground biomass, and harvest index. Two separate scenario analyses were conducted using the long-term (26 years) weather records for Bunkure (representing the SS) and Zaria (representing the NGS). The early and extra-early varieties were used in the SS while the intermediate and late varieties were used in the NGS. The result of the scenario analyses showed that early and extra-early varieties grown in the SS responds to increased sowing density up to 8.8 plants m−2 when the recommended rate of N fertilizers (90 kg N ha−1) was applied. In the NGS, yield responses were observed up to a density of 6.6 plants m−2 with the application of 120 kg N ha−1 for the intermediate and late varieties. The highest mean monetary returns to land (US$1336.1 ha−1) were simulated for scenarios with 8.8 plants m−2 and 90 kg N ha−1, while the highest return to labor (US$957.7 ha−1) was simulated for scenarios with 6.6 plants m−2 and 90 Kg N ha−1 in the SS. In the NGS, monetary return per hectare was highest with a planting density of 6.6 plants m−2 with the application of 120 kg N, while the return to labor was highest for sowing density of 5.3 plants m−2 at the same N fertilizer application rates. The results of the long-term simulations predicted increases in yield and economic returns to land and labor by increasing sowing densities in the maize belts of Nigeria without applying N fertilizers above the recommended rates.

ОПТИМІЗАЦІЯ ГУСТОТИ СТОЯННЯ РОСЛИН СОЇ ЗАЛЕЖНО ВІД ГРУПИ СТИГЛОСТІ СОРТУ ДЛЯ УМОВ ПІВНІЧНО-СХІДНОЇ ЧАСТИНИ ЛІСОСТЕПУ УКРАЇНИ

The aim of the article is to establish the optimal sowing density of soybean plants depending on the maturity group of the variety to obtain consistently high yields. For this purpose, new varieties of soybeans Siverka, Medison and Sihaliia were taken for research, which differ not only in the duration of vegetation, but also in morphological characteristics. The object of the research is the process of forming soybean yield depending on the variety and standing density. The subject of the research is the varieties: early-ripening Siverka from the Institure of Agriculture of the National Academy of Agrarian Sciences of Ukraine (NAAS), year of registration - 2013, plant growth type - intermediate; middle-early Medison from Hyland seeds: it has been in the Register of the varieties of Ukraine from 2008; type of growth - indeterminate; middle-ripening Sihaliia fro Dunai Agro, which was brought in the Register of the varieties of Ukraine in 2014, type of growth - indeterminate; seeding rates of 600, 700 and 800 thousand per ha; soybean grain yield. The forerunner in the experiments was winter wheat. Soil preparation consisted of stubble peeling and fallow plowing. Before sowing cultivation with harrowing was conducted. Sowing was carried out at a time when the soil at thr depth of 10 cm warms up to 100C in the usual row manner with a row spacing of 15 cm to the depth of 4-5 cm. Crops care laid in carring out preemergence and two post-emergence harrowings. Studies have shown that soybean yields depended on the variety and density of plants. Thus, on average over the years of research, the yield in the variety Siverka varied from 2.01 t per ha at a density of 800 thousand pieces per ha and decreased as it thickened to 2.26 t per ha at a density of 600 thousand pieces per ha. In the Medison variety, the yield ranged from 2.18 t per ha at a density of 600 thousand units per ha to 2.41 t per ha at a density of 700 thousand units per ha. In the Sihaliia variety, the yield varied from 2.28 t per ha at a density of 600 thousand pieces per ha to 2.50 t per ha at a density of 800 thousand pieces per ha. The maximum yield for the years of research (2.09-2.39 t per ha) the variety of Siverka formed at a density of 600 thousand pieces per ha. In the Medison variety the highest yield (2.31-2.52 t per ha) was obtained at a standing density of 700 thousand pieces per ha. The yield of the Sihaliia variety depended to a greater extent on the weather and climatic conditions of the year. Thus, under drier conditions in 2017, the highest yield of the variety (2.44 t per ha) was formed at a density of 700 thousand pieces per ha. Under more favorable conditions, the highest yield was obtained at a density of 800 thousand pieces per ha - 2.51-2.69 t per ha. Depending on the weather and climatic conditions of the years of research, the highest yields of all varieties were obtained under favorable conditions in 2019 - 2.27-2.56 t per ha. Under drier and cooler conditions in 2017, the yield of all varieties was lower by 0.13-0.41 t per ha. Thus, in the conditions of the north-eastern part of the forest-steppe of Ukraine, in order to obtain a high soybean yield, it is necessary to take a differentiated approach to the choice of the optimal standing density depending on the maturity group of the variety. Optimal conditions for the formation of maximum productivity of early-ripening soybean variety Siverka were created in the agrophytocenosis at densities of 600 thousand per ha, for medium-early variety Medison - 700 thousand per ha, and for medium-ripening variety Sihaliia - 700-800 thousand pieces per ha.

CARBON, NITROGEN, AND ORGANIC MATTER OF SOIL IN AN INTEGRATED CROP-LIVESTOCK SYSTEM

This study aimed to evaluate the effect of the integrated crop-livestock system on the contents and stocks of total organic carbon, total nitrogen, and soil organic matter. The experiment was carried out between April 2016 and February 2017, in a randomized block design in a strip-block scheme, with additional control treatment (fallow) and four repetitions. The treatments consisted of two densities of oat sowing (40 and 60 kg ha-1) in strips A and different grazing frequencies (without grazing - WG, one grazing - 1G, and two grazing - 2G) in strips B, besides fallow as a control treatment. The determinations of the contents of total organic carbon (TOC), total nitrogen (TN), and organic matter (SOM) were carried out in the soil layers of 0-5, 5-10, and 10-20 cm. Samplings were carried out after oat management, in the winter, and after soybean harvest, in the summer. The sowing density of black oats and the grazing frequencies were not able to promote changes in the total organic carbon and in the TOC stock, regardless of the time of evaluation. The use of 40 kg ha-1 of oat seeds would be recommended, as it does not promote changes in the increase in MOS, thus generating savings in the acquisition of seeds. The use of the lowest density of oat without grazing and one grazing promoted changes on the total nitrogen in the 5-10 cm layer after the removal of oats, when compared to the fallow, and it presented content similar to the management with two grazings.

The effect of Elymus nutans sowing density on soil reinforcement and slope stabilization properties of vegetation\u2013concrete structures

Elymus nutans is an herbaceous plant that can be used to restore degraded alpine and subalpine ecosystems. Here, we evaluated how sowing density affects soil reinforcement and slope stabilization properties of vegetation–concrete structures. To investigate the optimal sowing density of E. nutans in vegetation–concrete applications for slope protection, six experimental treatments were established with different plant densities: control, I (1100 seeds/m2), II (2200 seeds/m2), III (3300 seeds/m2), IV (4400 seeds/m2), and V (5500 seeds/m2). Several parameters of plant growth in addition to soil reinforcement and slope stabilization properties were measured in each treatment, as well as the associations among parameters. As density increased, aboveground biomass continually increased, and plant heights, root surface areas, root lengths, and underground biomass all first increased and then decreased. In contrast, tiller numbers and the average root diameter gradually decreased with increasing density. Increased density also resulted in increased maximum water interception levels by aboveground stems and leaves. The maximum water interception by the aboveground stems and leaves was 41.75% greater in the highest density treatment (V) compared to the lowest density treatment (I). However, the enhancement of erosion resistance and soil shear strength first increased and then decreased as density increased, with maximal values observed in the medium-high density treatment (IV). Sowing density was highly correlated with aboveground biomass, plant heights, tiller numbers, and the maximum level of water interception by stems and leaves. Thus, sowing density directly influenced soil reinforcement and slope stabilization properties of aboveground plant components. However, density was not significantly correlated with belowground biomass, root lengths, root surface areas, the enhancement of erosion resistance, and soil shear strengths. Therefore, sowing density indirectly influenced soil reinforcement and slope stabilization of belowground plant components. Following from these results, we suggest that the optimal sowing density of E. nutans is approximately 4400 plants/m2 in their application within vegetation–concrete structures used for slope protection.

Ancient Wheat Species (Triticum sphaerococcum Perc. and T. persicum Vav.) in Organic Farming: Influence of Sowing Density on Agronomic Traits, Pests and Diseases Occurrence, and Weed Infestation

Crop management should be determined to reintroduce ancient wheat. This study aimed to determine: i. the response of the yield of ancient wheat on sowing density; ii. the impact of sowing density on plant health, weed infestation and pest occurrence. Field experiments were carried out in Poland, on three organic farms. The factors were: (1) wheat species: Persian wheat (Triticum persicum Vav.) and Indian dwarf wheat (T. sphaerococcum Perc.), (2) sowing density (400, 500, and 600 grains m−2). Increasing the sowing density of T. sphaerococcum from 400 to 600 grains m−2 increases the grain yield and reduces the pest pressure (Oulema spp. and Aphididae). Sowing densities did not affect the severity of powdery mildew at stem elongation as well as root rot and eyespot at the development of fruit. At the highest sowing density, the leaf area with tan spot symptoms was the highest. The eyespot symptoms occurred more frequently and the damaged plant surface caused by Oulema spp. was larger on T. sphaerococcum. Persian wheat turned out to be more susceptible to weed infestation. Indian dwarf wheat and Persian wheat are useful for organic farming, and the sowing density should be 500 or 600 grains m−2 and 400 grains m−2, respectively.

Effects of rare arable plants on plant diversity, productivity and soil fertility in agricultural fields

Agricultural intensification has caused a strong agro-biodiversity decline in Europe, with high losses in rare arable plants. A better understanding of the relationship between these species, agricultural productivity, and other ecosystem functions can improve conservation management. The study was performed on an experimental field near Munich. To examine the results under field conditions, study plots were additionally established on ten arable fields distributed in the Munich Plain, an area with nutrient poor soils in southern Germany. We sowed a mixture of ten rare arable plant species at varying crop densities and compared them to plots without rare arable plants. To assess the effects on plant diversity and productivity, the cover and species richness of rare and common arable plants and the crop and arable plant biomass were assessed. The organic matter, nitrogen concentration, as well as the biomass and abundance of earthworm (biannually sampled for two years) were analyzed to determine the impact on soil fertility.Our results showed that sowing rare arable plants did not negatively affect crop biomass. Arable plant biomass and cover of rare arable plants were highest when no crops were sown. There was no difference between reduced and regular crop sowing densities on rare arable plant cover. In our field experiment, earthworm occurrence and soil organic matter were probably influenced by pre-crops (two years of clover grass before the experiment) and summer droughts during the study period. However, no significant effects of sowing rare arable plants on soil fertility were detected. These results were partly verified from results of the field study.At least on nutrient-poor soils, rare arable plant sowing may be a suitable tool to promote plant diversity conservation without negatively affecting crop production. That the sowing of rare arable plants did not significantly affect the indicators for soil fertility suggests that biomass production of rare arable plants was too low to have an impact on the crops and a benefit for soil fertility. Insignificant effects on crop biomass also suggest that sowing rare arable plants does not automatically lead to crop losses. As organic matter, nitrogen concentration and earthworm occurrence slowly respond to environmental changes, they should be investigated in further long-term experiments. This study shows that conservation of rare arable plants and food production on nutrient poor fields can be combined. Therefore, land sharing may be a suitable tool for nature conservation and ecosystem functionality on arable land.

A million kernels of truth: Insights into scalable satellite maize yield mapping and yield gap analysis from an extensive ground dataset in the US Corn Belt

Crop yield maps estimated from satellite data increasingly are used to understand drivers of yield trends and variability, yet satellite-derived regional maps are rarely compared with location-specific yields due to the difficulty of acquiring sub-field ground truth data at scale. In commercial agricultural systems, combine harvesters with onboard yield monitors collect real-time yield data during harvest with high spatial resolution, generating a large ground dataset. Here, we leveraged a yield monitor dataset of over one million maize field observations across the United States Corn Belt from 2008 to 2018 to evaluate the Scalable Crop Yield Mapper (SCYM). SCYM uses region-specific crop model simulations and climate data to interpret vegetation indices from satellite observations, thus enabling efficient sub-field yield estimation across large regions and multiple years without reliance on ground data calibration. We used the ground dataset to compare alternative SCYM model implementations, define minimum required satellite observation criteria, and evaluate the sensitivity of satellite-based yield estimates to on-the-ground variation in management, soil, and annual weather. We found that smoothing annual time series data with harmonic regression increased 30 m pixel-level accuracy from r2 = 0.31 to 0.40 and reduced dependency on specific satellite observation timing, enabling robust yield estimation on 97% of annual maize area using only Landsat data. Agreement improved as the assessment was aggregated to field-level (r2 = 0.45) and county-level (r2 = 0.69) scales, demonstrating the need for fine-resolution ground truth data to better assess sub-field level accuracy in high resolution products. We found that SCYM and ground data showed a similar yield response to management and environmental variation, particularly capturing linear and nonlinear responses to sowing density, soil water holding capacity, and growing season precipitation. However, sensitivity to factors like soil quality and planting date was muted for SCYM estimates compared to ground-based yields. Random forest models were able to match SCYM performance when trained on at least 1000 ground observations, but performed poorly when tested on years and locations not represented in the training data. Our results demonstrate that satellite yield maps can provide much-needed information on multidecadal yield trends and inform yield gap analyses.

The Intraspecific competition as a driver for true production potential of soybean

Phenotypic plasticity of agricultural plants is considered to be one of the main means by which plants cope with the variability of environmental factors. A major contributor to plant plasticity is sowing density, which has a relevant impact on competitive intensity concerning plant density in different environments (CI) and absolute severity of competition (ASC) concerning plant-plant responses to each other in canopy. A field experiment with soybean was set up at the Experimental Station in Prusy, Krakow, to determine the impact of intraspecific competition on growth, plant architecture, nitrogen accumulation, and yield of soybean as an effect of seven different plant densities and weather conditions. The study showed that intraspecific competition in soybean was conditioned by sowing density and access to water, thus revealing the true plant productive potential. Low intraspecific competition increased with plant density causing an increase in the yield of plants. In the wet year of 2014, strong intraspecific competition resulted in high yield and nitrogen accumulation only up to a density of 42 plants m–2, compared to dry years when nitrogen uptake of soybean increased with plant density in full range. The CI and ASC competition indices were sensitive to the varying amount of rainfall. Greater rainfall during crop vegetation increased the intensity of competition as well as the absolute severity of competition and decreased the relative yield with increasing density. In contrast, drought reduced intraspecific competition, eliminating it entirely at over 52 plants m–2.
 Highlights - It is recommended to increase the sowing density in areas with less rainfall to compensate number of pods and number of seeds. - Low intraspecific competition increased yield and nitrogen accumulation in the seeds as the plant density increased.- In the wet year, strong intraspecific competition resulted in high yield and nitrogen accumulation only up to a density of 42 plants m–2. - At very low crop density, the intensity of intraspecific competition is very low and blocked the manifestation of the plants’ true production potential. - In the dry year, nitrogen uptake of soybean increased with plant density in the canopy up to the maximum density.

Агротехнические приемы возделывания люцерны на семена в условиях орошения в Нижнем Поволжье

Abstract. Legumes play a leading role in providing farm animals with high-quality and highly nutritious feed, while in the Lower Volga region, the traditional alfalfa crop plays a leading role. The productivity of alfalfa in production conditions is only a tenth of its potential. The purpose of the research is to determine the impact of reduced seeding rates, varietal characteristics, seeding time and use of siderates instead of mineral fertilizers on the seed productivity of the crop. The field experience included 2 terms of sowing – spring and summer, 3 variants of the soil nutrient regime: the natural background of nutrition and plowing of two types of sideral mixtures (sunflower + vetch and oats + radish); three variants of the density of herbage (40, 80 and 400 thousand plants/ha). Observations were made on three varieties of alfalfa (Leninskaya mestnaya, Vega 87 and Unitro). Records and observations were made in accordance with the generally accepted methods of experimental work. Results and practical significance. As a result of research, a favorable influence of sideral masses on the formation of a symbiotic apparate on alfalfa roots was revealed. In comparison with the natural background of nutrition, the number of nodules significantly increased in the variants with the plowing of siderates. The yield of seed alfalfa was also influenced by the density of sowing. More productive organs were formed in sparse grass stands, which contributed to an increase in the collection of seeds. The use of sideral mixtures also had a positive effect on productive shoot formation. The number of stems, brushes and seeds in the bean was 25–30 % more than in the control. Summer sowing favourably affected the seed productivity of alfalfa, its indicators were 1.2–1.6 times higher than the data obtained from the grass stands of the spring sowing season. Scientific novelty. For the irrigated conditions of the Lower Volga region, a comprehensive assessment of the participation of the main agrotechnical techniques in the implementation of alfalfa seed productivity is given: terms, methods and seeding rates with the use of siderates for soil fertilization.

Physicochemical and Enzymatic Soil Properties Influenced by Cropping of Primary Wheat under Organic and Conventional Farming Systems

The aim of the study was to assess the content of total organic carbon (TOC), macronutrients (P, K, and Mg), and glomalin (easily extractable glomalin-related soil protein (EEGRSP)) in soil, micronutrients (Zn and Cu) in soil and wheat, and the number of insects on plots in an organic (OF) and a conventional farming (CF) system, all against the background of alkaline phosphatase (AlP) and acid phosphatase (AcP) activity. The experimental design included two spring wheat species, Triticum sphaerococcum Percival and Triticum persicum Vavilov, and three sowing densities (grains m−2): 400, 500, 600. Statistical analysis (ANOVA, η2 effect size) showed significant variation in parameters under the influence of experimental factors. In the duration of the field experiment, TOC content in soil had decreased by 61% compared to the content before starting the experiment. The contents of P, K, and Mg and activity of AlP and AcP were higher in soil under T. sphaerococcum. With a sowing density of 600 grains m−2 under OF and CF, the significantly lowest macronutrient content and the highest AlP and AcP activity were found. The parameters tested (TOC, EEGRSP, P, K, Mg, TZn, TCu, AZn, CU in plant, AlP, AcP) were higher under the CF than under the OF system. The experimental factors (spring wheat species and number of germinating grains) were demonstrated to influence the content of the forms of both microelements in soil and plants. In CF, more content in the amount of Zn and Cu was found than in OF. But the content they had did not exceed the standards set for arable soils. Both wheat species had a significant impact on the concentration of glomalin in the soil from the fields cultivated in the OF system. In CF, a significant difference was caused by sowing density and by interaction between wheat species and sowing density. Insects preferred plants grown in the OF system compared to CF. Regardless of cultivation system, the number of insects was greater on the plots of T. sphaerococcum than on plots of T. persicum. There were more insects at higher sowing densities in plants grown in the OF system only.

Reintroduction of rare arable plants in extensively managed fields: Effects of crop type, sowing density and soil tillage

Vegetation of arable fields has changed significantly over the past decades as indicated by a marked decline in the abundance and diversity of arable plants. Thus, beyond the preservation of remnant populations, introduction of autochthonous seeds is a necessary measure to promote threatened arable plants and to restore agro-ecosystems. However, there is a lack of knowledge on the most suitable agricultural methods for plant establishment. This topic was investigated for three winter annuals (Legousia speculum-veneris, Consolida regalis, Lithospermum arvense) in a three-year field experiment in southern Germany. We established 14 management treatments with five replicates in a completely randomized block design. In year 1, arable plants were sown in a mixture of 850 seeds m−2 either without crop or with cereal crops in different sowing densities (25 %, 100 %). After crop harvest different types of soil tillage were applied (rotary cultivator, mouldboard plough). In year 2, four different crop types (autumn-sown spelt, spring-sown triticale, pea, clover-grass) were sown, and in year 3, rye was cultivated. Establishment was measured yearly as seed production of the rare arable plants, and their overall population growth rates were calculated at the end of the study period. Highest population growth rates were observed in L. speculum-veneris, followed by C. regalis and L. arvense. Population growth of the target plants decreased significantly with crop and weed cover averaged over the study period. Initial crop sowing densities had a significant impact on first-year establishment, with persisting effects in years 2 and 3. Best results were obtained without cover crop compared to cereals sown with 25 or 100 % sowing density. The establishment of target plants was also affected by crop type in year 2 (spelt > pea > spring triticale > clover-grass). However, establishment was overall high in year 3, when all plots were cultivated with rye. Type of soil tillage had no effect within the crop rotation ‘rye–clover-grass–rye’, while rotary cultivation in ‘without crop–rye–rye’ was positive for the establishment of L. speculum-veneris and L. arvense. The results indicate good opportunities for the reintroduction of rare arable plants under different crop rotations with best results for extensively managed fields with low crop competition.

English

Quinoa (Chenopodium quinoa Willd.) is a crop of increasing interest due to its agro-ecological adaptability and high nutritional properties. Few information is available on the adaptability of quinoa in the Sahel region, and on genotype’s phenological, morphological and agronomical responses to different planting methods and sowing density rates. To test the effect of planting and sowing methods, two separate experiments were carried out in Burkina Faso to examine the performance of different genotypes (Titicaca, Puno, Pasankalla and Negra Collana) to multiple planting methods (ridges, dibbling, broadcasting, transplanting, traditional-pits and flat sowing) and sowing density rates (from 80,000 to 200,000 plants ha-1). The results showed significant differences among genotypes in terms of growth attributes, with higher yields when sown in ridges (10.7, 8.4 and 5.7 g plant-1 Puno, Pasankalla and Titicaca, respectively). In addition, higher yields were observed under low density rates, with plant spacing being compensated by changes in branch system. However, higher yields were reported per unit area (Titicaca with 98.8 g m-2) under high density treatments (200,000 plants ha-1). As a conclusion, the use of short cycle varieties (Titicaca and Puno) sown in ridges at high density rates was recommended. Key words: Africa, agricultural management, genotypes, phenology, physiology. &nbsp

Comparing the Growth Performance and Yield Parameters of Two Cowpea Varieties (Vigna unguiculata (L) Walp.) under Different Sowing Densities

Cowpea is a food legume very popular for its seeds and leaves in Côte d’Ivoire. This plant constitutes a significant source of financial income for vulnerable populations in rural areas. However, it production remains low in the growing areas because of the traditional practice of this food. In other words, the cultivation technique adopted for this plant is not appropriate, in particular the sowing density. To solve this problem, research work has been undertaken in 2019 and 2020 with the aim of improving the production of this crop. The first year consisted of identifying the most productive variety in a complete random arrangement with three replicates. During the second, the trials concerned the optimization of the production of this variety by controlling the seed density. For this purpose, the sowing was carried out according to three sowing densities: low density (40.000 plants/ha), middle density (134.444 plants/ha) and high density (280.000 plants/ha) in a complete random device with three repetitions. The parameters collected from sowing to harvest and after harvest were subjected to statistical analysis. Thus, it emerges from this analysis that the creeping variety recorded the best values of the growth parameters. This variety could be used as fodder for animal feed. For variables related to production, the highest values were obtained with the upright variety. The yield of this variety is doubled when cultivated at low density. Thus, for the financial and food empowerment of cowpea producers, they will have to take an interest in the upright variety and cultivate it in low density.

Root morphological traits and distribution indirect-seededrice underdenseplanting with reducednitrogen.

Water and nutrient absorption from soil by crops mainly depend on the morphological traits and distribution of the crop roots. Dense planting with reduced nitrogen is a sustainable strategy for improving grain yield and nitrogen use efficiency. However, there is little information on the effects of dense planting with reduced nitrogen on direct-seeded inbred rice. Two-year field experiments were conducted with minirhizotron techniques to characterize the root morphological traits and distributions under different nitrogen application rates and sowing densities in two representative inbred rice varieties, Huanghuazhan (HHZ) and Yuenongsimiao (YNSM), grown under three nitrogen application rates (N0: 0 kg ha–1, LN: 135 kg ha-1, HN: 180 kg ha–1) and two sowing densities (LD: 18.75 kg ha−1, HD: 22.5 kg ha−1). Our study showed that dense planting with low nitrogen improved grain yield partly due to the increased panicle number. The higher sowing density with low nitrogen significantly affected the total root number (TRN), total root length (TRL), total root surface area (TRSA), and total root volume (TRV). There was a significant positive correlation between grain yield and TRL in the 10–20-cm soil layer (P < 0.05). The root morphological indexes were positively correlated with dry matter accumulation (P < 0.05) and negatively correlated with nitrogen content (P < 0.05) at the maturity stage. This study showed that a high sowing density with low nitrogen application can improve root morphology and distribution and increase grain yield and nitrogen use efficiency in direct-seeded inbred rice.

Sowing density and clipping management: effects on the architecture and yield of dual-purpose wheat

The dual-purpose wheat stands out as a complementary alternative for forage supply during the winter period. Therefore, this work had the objective of evaluate the performance characteristics in five genotypes of dual-purpose wheat submitted to different sowing densities and different clipping managements. The experiment was carried out during the 2016 and 2017 harvests. The experimental design was a randomized block design, organized in a factorial scheme, with five dual-purpose wheat genotypes (BRS Tarumã, BRS Umbu, BRS Figueira, BRS Guatambu and BRS 277) x five sowing densities (75, 150, 225, 300 and 375 seeds m²) x four clipping operations (zero, one, two and three clippings), arranged in three replicates. The measuring of characters were number of fertile tillers, seeds yield, angle of flag leaf, chlorophyll content and flowering. The genotype BRS Tarumâ is superior in number of fertile tillers and chlorophyll index for all the sowing densities, as well, the flowering is influenced direct by clipping managements. The sowing density of 75 seeds m-2 is not indicated for dual-purpose wheat independent of the clipping management. The seeds yield is amplified thought the increase in sowing density, however, advancing in clipping levels there is a decrease in forage yield.

Bromatological composition and dry matter production of corn hydroponic fodder

The objective was to evaluate sowing density influence on hydroponic corn fodder bromatological composition, harvested in different ages raised on grass mix substrate. The experimental design used was completely randomized with six replications for each treatment, using 2.0 m² plots (1.0 x 2.0 m). The densities were distributed into factorial array (4x4), consisting in four sowing densities (1.0, 1.5, 2.0 and 2.5 kg m-²) and four cutting ages (10, 15, 20 and 25 days). The dry matter content (DMC) and production (DMP) and crude protein (CP), acid detergent fiber (ADF), Fiber neutral detergent (FND) and ethereal extract (EE) were analyzed each cutting age. In terms of DMP (kg m-²), EE (%) and DMC (kg m-²), it is recommended to use the density 1.0 kg m-² with cutting age of 25 days. Regarding CP (%) the best result was at 15 days of cut and density 2.5 kg m-² and the values for FND (%) and ADF (%) were higher at 25 days at 2.0 kg density 2,0 kg m-². The choice of both best harvesting age and density will depend on what is desired of the nutritional forage (CP, EE, NDF, ADF, DMC and DMP) as well its destination, since very close values were found in all analyzes, regardless of density and age of harvest analyzed.