Sowing Density Research Articles

Assessment of Sowing Density Impact on Water Front Advancement and Infiltration in Furrow Irrigation

This research aims to evaluate the impact of durum-wheat sowing density on wetting front advancement and water infiltration rate along the furrow length. In addition, durum wheat yield and furrow irrigation performance under the different sowing densities were assessed. For that purpose, a field experiment was conducted under semi-arid conditions in Tunisia using four durum-wheat sowing densities: SD1 (250 seeds m−2), SD2 (350 seeds m−2), SD3 (450 seeds m−2) and SD0 (bare soil). The results reveal that water front advancement tends to be inversely proportional to sowing density. In fact, under the SD3 treatment, both irrigation duration and applied water volume increased about twofold compared to those recorded under SD0, resulting in an increasing soil infiltration rate. Furthermore, the two-point method performed well in estimating water front advancement, with an R2 value close to 1. Regarding durum wheat yield, values varied between 3.5 and 4.9 t ha−1 with the highest value attributed to the SD3 treatment. Meanwhile, higher irrigation water productivity was recorded under SD1. Considering irrigation performance indicators, the results indicate that distribution uniformity (DU) increases with increasing sowing density. Moreover, the lowest application efficiency values (75%) were recorded under the SD0 and SD3 treatments as compared to 82% for SD2 and 80% for SD1.

Yield of common bean depends on the effect of agrotechnical measures in the conditions of the Forest Steppe of the right bank

Aim. To study the peculiarities of the formation of grain productivity of new varieties of common beans depending on the method of sowing and the density of plants. Methods. Field, measuring­weighing ­ for crop harvest accounting, mathematical and statistical. Results. The results of research on the study of the peculiarities of the formation of grain productivity of new varieties of common bean under different methods of sowing and plant density on typical low­humus chernozems, conducted during 2020­2022 at the experimental field of the SE « RF Salivonkivske» of the Institute of Bioenergy Crops and Sugar Beet of the National Academy of Sciences of Ukraine, are presented. Conclusions. All varieties of common beans studied in the experiment formed the highest grain productivity under wide­row sowing with a row width of 45 cm and a plant density of 600 thousand/ha ­ 2.72­3.24 t/ha.With the same density and the usual row method of sowing with a row width of 15 cm, crops formed no more than 2.33­2.75 t/ha of grain. With both methods of sowing, both a decrease and an increase in the density of plants on the area negatively affected the formation of the yield of bean crops. Under the optimal technological model of cultivation, the maximum grain productivity ­ at the level of 3.24 t/ha ­ was provided by the bean variety of ordinary Bilosnizhka. Ros and Slavia varieties were inferior to it, respectively by 0.44 and 0.52 t/ha. According to the results of pairwise correlation, a correlation dependence was established for the culture between the amount of grain yield of common bean and hydrothermal conditions during its growing season in relation to: the sum of active temperatures (r = 0.56) and the amount of precipitation (r = 0.57).

PHYSIOLOGICAL AND BIOCHEMICAL ASPECTS OF OPTIMISING THE SOWING RATE OF SPRING AND WINTER Pisum sativum FORMS

The winter and spring varieties of peas (Pisum sativum) require careful study of the entire range of technological measures, including seeding rates, as the basis for optimal sowing density and the formation of phytocenose crops. This issue has not been resolved to date, not only in the context of agrobiological justification but also in everyday practice in Ukraine. This research was carried out in a field experiment in a three-way factorial experiment: factor “A” was the type of development - winter and spring; factor “B” was the variety - spring peas (Svit and Darunok Stepu) and winter peas (Moroz, Enduro and Baltrapp); and factor “C” was the seeding rate. According to the field studies, differences in the physiological and biochemical parameters of the P. sativum test culture characterised the photosynthetic activity of the plants, considering the type of development and variety. The winter varieties of P. sativum were characterised by a higher chlorophyll content (by 35–40%) compared to the spring varieties, which had an economic effect with an increase in the yield of dry biomass of the experimental crop and a decrease in seeding rates, with the formation and increase in grain yield by 14–18%. The intensity of chlorophyll in the process was not a determining factor in the accumulation of organic biomass. The extensive nature of the integration complex was noted (the amount of chlorophyll - the amount of biomass). At the optimal seeding rate, a certain specificity was observed in different types of P. sativum: for spring varieties, the sufficient rate was 0.9 million seeds/ha, and for winter varieties, it was 0.7 million seeds/ha. For varieties with a low productivity level (spring - Svit and winter - Moroz), the optimum sowing rate was around 0.7 million seeds/ha. The increase in the seeding rate was accompanied by a decrease in the content of various chlorophyll fractions from 10–12% to 20–26%.

The Effects of Different Sowing Density and Nitrogen Topdressing on Wheat Were Investigated under the Cultivation Mode of Hole Sowing

Hole sowing is a new and efficient cultivation method with few studies. This study investigated the effects of different sowing densities and nitrogen topdressing at the jointing stage on dry matter, quality, and yield under wheat hole sowing to provide a theoretical basis for integrating wheat fertilizer and density-supporting technology. In this study, a two-factor split-plot design was used. The sowing density was the main plot, and four levels were set: D1, D2, D3, and D4 (238, 327, 386, and 386 suitable seeds·m−2). The four sowing levels were sown according to 8 grains/hole, 11 grains/hole, 13 grains/hole, and 16 grains/hole, respectively, with a row spacing of 25 cm and a hole spacing of 13.5 cm; the amount of nitrogen fertilizer applied at the jointing stage was the sub-area, with four levels: N1, N2, N3, and N4 (0, 60, 120, and 180 kg·ha−1). After two years of experimental research, the following main conclusions are drawn: the use of high sowing density and nitrogen topdressing is helpful to improve the dry matter quality of wheat spikes at the maturing stage; the sowing density had significant or highly significant effects on protein content, starch content, and sedimentation value. The yield from 2018–2019 reached a maximum of 8448.67 kg·ha−1 under D4N4 treatment, and the yield from 2019–2020 reached a maximum of 10,136.40 kg·ha−1 under D4N3 treatment. Therefore, the combination of 225 kg·ha−1 sowing density and 120–180 kg·ha−1 nitrogen topdressing at the jointing stage can be used in field production, which can help improve wheat production potential. Similarly, understanding the interaction between wheat hole sowing and different sowing densities and nitrogen topdressing amounts provides a practical reference for high-yield wheat cultivation techniques.

Production and Growth Performance of Nannochloropsis oculata (Droop) Hibberd in the Helical Photobioreactor

Phytoplankton species preferred in marine fish farming are the primary food source in the larval and young stages of bivalve mollusks, along with some fish and shellfish larvae. For this reason, selecting the appropriate phytoplankton and production technique for feeding marine fish larvae is crucial. Nannochloripsis oculata microalgae species, widely used in rearing sea bream and sea bass larvae and feeding rotifers, has an essential place in our country. N. oculata microalgae species, which is used in rearing sea bream and sea bass larvae and feeding rotifers, was produced in a helical photobioreactor by applying a continuous production technique at 30 ‰ salinity, and its growth performance was aimed to be investigated. In the study, N. oculata was grown in a helical photobioreactor at 30‰ salinity by applying the continuous production technique for two weeks, and the daily cell number and specific growth rate were determined. The study was repeated three times. The supply of live feed for marine fish fry and hatcheries established for this purpose is one of the most critical problems. The latest technology in the production of microalgae, which is the primary link of the live feed chain in this sector, is continuous algae production in helical tubular reactors. The helical tubular reactor used in the study consists of a transparent hose system consisting of a completely tubular helical reactor designed for microalgae production. The helical tubular continuous production system offers more efficient and economically more convenient alternatives than existing production systems. One of the most essential advantages of this system is that the system can be designed without requiring significant capital. The continuous culture technique allows the application of long-term and safe algae cultures. With this system, besides providing continuity in production, the negativities in batch production can be eliminated with adequate light. Since the algae production with the continuous method in the spiral photobioreactor remains in the maximum growth phase for a longer time than the batch production, it is a system with high production efficiency and quality, and production capacity is guaranteed. In addition, the algae product harvesting in the continuous system ensures the daily harvesting of algae as much as half of the system volume. A helical reactor enables automation in algae production and high-quality production over long periods. In the study, the sowing density of N. oculata was determined as 1.068x106 ±0.006 cells/mL. Algin cell growth increased logarithmically during the first five days. From the 5th day to the 15th day, the increase in the number of cells was determined as 12.35x106±0.165 cells/mL at the highest and 8.76x106±0.709 cells/mL at the lowest. However, on the 13th day, it was determined that the increase in algin cells was 12.35x106±0.165 cells/mL, and the specific growth rate decreased by 0.189±0.016 divisions/day. As a result of the study, the number of cells of N. oculata algae 5-15 increased. It was determined that it increased 10 times between days. In this context, it was possible to harvest half of the reactor volume of algae daily at maximum cell density for long periods in the helical reactor

Experimental Study on Mechanical Properties of Hemp Fibers Influenced by Various Parameters

Hemp fibers produced by different extraction techniques that were cultivated in the Portuguese districts of Bragança and Mirandela under various nitrogen fertilization and planting density conditions are examined and mechanically described in this paper. The objective of this study is to evaluate the influence of sowing density, nitrogen fertilization, sample location, and extraction method in order to improve the mechanical properties of hemp fibers. To achieve this, we determined the modulus of elasticity, the tensile strength, and the density. The mean value for the modulus of elasticity was 92.44 ± 7.44 GPa, the mean of tensile strength was 564.98 ± 167.03 MPa, and the mean of the density was 1.64 ± 0.24 g cm−3. We performed a statistical analysis of all parameters using ANOVA and found that the retting method had the greatest influence among all parameters. The associated effects of nitrogen fertilization and sowing density revealed an important influence on tensile strength and specific tensile strength, respectively.

Varietal features of elements of soybean cultivation technology during irrigation

An important advantage of soybean (Glycine max (L.) Merr.) over other crops is a prominent protein content and a balanced amino acid composition, in connection with which the creation of a wide range of varieties becomes relevant, as their cultivation could meet the needs of processing industries, as well as the development of optimal varietal cultivation technologies, which allow unleashing the genotypic potential of productivity. The purpose of this study was to substantiate the specific features of the formation of productivity of modern soybean varieties depending on the elements of cultivation technology in irrigation conditions. Research methods: field, morphometric, laboratory, statistical (correlation and regression analysis). Field studies were conducted during 2019-2021 in the agroecological zone of the Southern Steppe within the Kakhovka Irrigation System. Features of the growth and development of soybean varieties of different maturity groups were established: fast crops – Monarkh, Arnika, early crops – Pysanka, Sofia, mid-early – Sviatohor, Evridika. The yield of soybean varieties varied depending on the timing of sowing, plant density, and varietal characteristics. The maximum productivity of crops of early varieties Arnika and Monarkh at 2.81-3.39 t/ha was formed during the sowing period of May 1 and the optimal sowing density of 700 thous. plants/ha. In the group of early crops, Sofiia and Pysanka varieties showed the maximum yield of 3.17-3.22 t/ha during the sowing period of May 1 and plant density of 700 thous. plants/ha. Varieties of the mid-early crops Sviatohor, Evridika gave the maximum yield of 3.76-4.28 t/ha for sowing on May 1 and a density of 500 thous. plants/ha. To obtain the maximum yield of soybeans under irrigation conditions, there is an optimal sowing period and an optimal density of coenosis for each maturity group of varieties: fast crops showed the maximum yield when sowing on May 1 and with a density of 700 thous. plants/ha, early and mid-early crops – when sowing on May 1 and with a plant density of 500 thous. plants/ha. The results of this study can be used in production conditions to adjust the elements of agricultural technology of soybean seed production and obtain high yields with a prominent level of profitability

Pod positioning and grain yield of common bean as affected by sowing density, nitrogen fertilization and fertilization depth

The positioning of pods in common bean directly affects grain losses in mechanized harvesting. However, only few studies have assessed facttors that can affect pods positioning. The objective of this work was to determine the effect of plant density, nitrogen fertilization, and fertilization depth on the distribution of pods of the common bean. The field experiments were carried out in two cropping seasons, 2017 and 2018, during the winter period in the Cerrado region. The experimental design was randomized blocks in a 4x2 factorial scheme, with four replications. The treatments consisted of the combination of four sowing densities (5, 10, 15, and 20 plants m-1) with two depths of fertilizer application (6 and 12 cm). The results allowed inferring that the depth of the fertilization does not affect the distribution of pods in the common bean. Plant density does not affect common bean grain yield. More than a quarter of the common bean pods of the BRS FC104 are positioned close to the ground, below 100 mm, in the area where harvester machines operate. Nitrogen fertilization and plant density affect the distribution of pods in common bean plants. At higher doses of N (90 kg ha-1), plant density should be increased. On the other hand, at lower doses (45 kg ha-1), plant density must be reduced. It is concluded that the sowing density can be an efficient strategy to provide the highest positioning of pods in the upper part of the common bean plants, reducing harvest loss.

Improvement of seedling quality of red jabon (Neolamarckia macrophylla (Roxb.) Bosser) through seed sowing techniques and seed invigoration

Red jabon (Neolamarckia macrophylla) is one of potential tree species, but there are some problems in its cultivation. Intermediate seed character and very small seed sizes with little food reserves often cause the low germination, low growth of the seedlings, and the sowing of the seeds to be too dense, resulting in an abnormal number of seedlings. The purpose of the research was to improve the seed germination and seedling quality of red jabon by adjusting the sowing density and seed invigoration treatment using hormonal and biopriming. Two experiments were conducted, that is, (1) identification of optimal seed density on the several combinations of sowing media (top soil, rice husk and compost) and (2) evaluation of the most suitable hormonal priming (GA3) and biopriming (liquid organic fertilizer, LOF) applications. The use of top soil media with a seed density of 0.5 g/400 cm2 can produce the highest pure live seed (PLS), that is, 721.67 seedlings/0.5 g. The seed treated by hormonal and bio-priming significantly affected the seed germination and seedling growth. Soaking seed in GA3 100 ppm for 4 days produced the highest of the PLS (764 seedlings/0.5 g), followed by soaking in LOF for 3 days and GA3 50 ppm for 4 days. The highest seedling height was generated from soaking the seeds using LOF for 3 days. The highest root collar diameter and biomass of red jabon seedlings were obtained from the treatment of seeds immersed in the GA3 50 ppm for 3 days. The best quality index value of red jabon seedlings was produced from the treatment of seeds immersed in the hormone GA3 50 ppm for 3 days. In general, a sowing density of 0.5 g/400 cm2 in top soil media and seed soaking treatment in GA3 50 ppm or LOF for 3 days can improve germination and growth of red jabon seedlings.

Soybean performance in succession to the intercropping of corn with marandu grass and pigeonpea in an integrated agricultural production system

Integrated agricultural production systems have been improved with the introduction of Urochloa grasses aiming at obtaining straw for a no-tillage system (NTS) and the increase of legumes, which promote physicochemical improvements in soils and guarantee intensification and sustainability of production. This study aimed to evaluate the agronomic traits and yield of soybean in succession to the intercropping of corn with marandu grass and/or pigeonpea in five populations of plants harvested for silage production. The experiment was carried out in the Cerrado region of Selvíria, MS, Brazil, during the 2016/17 and 2017/18 agricultural years, in an Oxisol. The experimental design consisted of randomized blocks, with four replications. The treatments were arranged in a 2×5 factorial scheme, consisting of off-season corn intercropped with pigeonpea (Cajanus cajan (L.) Millsp.) and off-season corn intercropped with marandu grass (Urochloa brizantha) and pigeonpea, in addition to five sowing densities (0, 6, 12, 18, and 24 seeds m-1). Soybean was planted in succession aiming to evaluate the effect of remaining straw on crop performance. Soybean grown in succession to the triple intercropping of corn with marandu and pigeon pea shows increased productivity.

Influence of plant density on productivity and quality indicators of sunflower oilseeds

In the agricultural technology of sunflower cultivation, plant density in crops is one of the main conditions that determine its further productivity [5]. The optimal sowing density of sunflower can vary widely and depend on various factors, such as the varietal characteristics of plant, the soil-climatic zone of its cultivation, specific weather conditions and, above all, the moisture supply of plants, especially in the critical phases of sunflower development (flowering and grain filling) [ 8]. It has been proved that the optimal plant density in sunflower crops is such that not only normal growth processes and development of each plant are ensured, but the maximum possible productivity per unit of sown area is also formed. In this regard, in 2018–2020, in the flat zone on the leached chernozems of LLC «Zarya» of the Shovgenovsky district of the Republic of Adygea, studies were carried out (according to B.A. Dospekhov «Methodology of field experience») in order to study the reaction of new promising sunflower hybrids (Gorstar, Natali, Iren, selection of Federal State Budgetary Scientific Institution «FSC «VNIIMK named after V.S. Pustovoit», Krasnodar) to change the number of plants per hectare. As a result of the research, the degree of influence of the studied factor on the formation of productive qualities of the studied sunflower hybrids has been established– the diameter of the anthode, the number of oil seeds in it, the mass of achenes from one anthode, the weight of 1000 achenes, the fulfillment of achenes, seed yield, total collection of oil from one hectare area). The studies have shown that the maximum seed yield has been achieved in the hybrids Gorstar and Iren, formed on the second variant (50 thousand pieces/ha). In the Natalie hybrid, the maximum yield was recorded in the variant with a plant density of 60 thousand pieces/ha. From this, it should be noted that with the option of 50 thousand pieces/ha, the Natali hybrid turned out to be 0.62–0.61 t/ha less productive than the Gorstar hybrid and 0.52–0.56 t/ha than the Irene hybrid.The studies were carried out on the equipment of the «Expert» Common Use Center of FSBEI HE «MSTU».

Relationship between canopy coverage at the initiation of stem elongation and lodging in wheat

While lodging in wheat appears to correlate with the ratio of canopy coverage at the initiation of stem elongation (CC30), a mechanistic understanding of the relationship between lodging index and CC30 is lacking. The objective of this study was to examine more closely the relationship between lodging and CC30 and to identify the most effective sowing densities and/or planting patterns in reducing lodging. The CC30 was adjusted by varying the sowing density and planting pattern, i.e., wide vs narrow-spaced rows and altering the seed spacing within the row and by spread sowing. We found that CC30 was positively correlated with the lodging degree at maturity and was negatively correlated with internode dry weight per unit length. The CC30 for a sowing density of 3 g m−2 (which is about half the conventional sowing density in Japan) was low at a range of 28–75 %. In these treatments, CC30 was lowest under spread sowing where the spacing between plants was greatest. The yield of the 3 g m−2 spread-seed treatments was more than 500 g m−2. This yield is comparable to that of the other treatments even though the sowing density was much lower. The aboveground N accumulation at maturity of the 3 g m−2 spread-seed treatments was similar to that of the other treatments. As found in the spread-seed treatments, our results suggest that lowering CC30 by reducing the sowing density and/or by changing the planting pattern, increased the spacing between seedlings and thus helped to prevent lodging while still retaining high yields.

Influence of seeding density on agronomic parameters of cowpea (Vigna unguiculata L.) accession grown in Daloa, west center of Côte d’Ivoire

Cowpea (Vigna unguiculata L.) is most important food legume in tropical regions of Africa. In Côte d'Ivoire, its cultivation is neglected and is carried out on small surfaces with a strong concentration in North of the country. The objective of this study was to determine, in addition to the sowing density, the ideal number of plants per sowing hole for a better cowpea production. Experimental design used was a completely randomized Fisher block with three replications and six treatments per block. The tested spacings with the number of plants per sowing hole are : 20 cm x 20 cm x 01 plant per sowing hole, 20 cm x 20 cm x 02 plants per sowing hole; 30 cm x 30 cm x 01 plant per sowing hole, 30 cm x 30 cm x 02 plants per sowing hole; 40 cm x 40 cm x 01 plant per sowing hole, 40 cm x 40 cm x 02 plants per sowing hole. Observations were made on nine agronomic parameters (plant height, number of leaves, number of branches, span, fresh biomass, number of pods, fresh weight of pods, dry weight of pods and grain weight. Results show that seeding densities and number of plants per sowing hole significantly influence the agronomic parameters. Thus, the lowest sowing densities (62500 plants/ha) corresponding to 40cm x 40cm spacing with one plant per sowing hole gave the best yields while the highest densities (250000 plants/ha) corresponding to 20cm x 20cm spacing with two plants per sowing hole gave the lowest yields for all agronomic parameters.

Root Characteristics for Maize with the Highest Grain Yield Potential of 22.5 Mg ha−1 in China

In maize (Zea mays L.), rational root structure promotes high grain yield under dense sowing conditions. This study was conducted at Qitai Farm in Xinjiang, China, in 2019 and 2021. A traditional wide and narrow row planting method was adopted, with wide rows of 0.7 m and narrow rows of 0.4 m. The cultivars DH618 and SC704, which have grain yield potentials of 22.5 and 15 Mg ha−1, respectively, were selected for study of the root structure and distribution characteristics under high-yield and high-density planting conditions. The highest yield (20.24 Mg ha−1) was achieved by DH618 under a planting density of 12 × 104 plants ha−1. The root structure of DH618 was well developed at that planting density, and the root dry weight (RDW) was 17.49 g plant−1 and 14.65 g plant−1 at the silking and maturity stages, respectively; these values were 7.56% and 11.86% higher, respectively, than those of SC704. At the silking stage, the proportions of RDW at soil depths of 0–10, 10–20, 20–40, and 40–60 cm were 66.29%, 11.83%, 16.51%, and 5.38%, respectively, for DH618; over the 20–60 cm soil layer, this was an average of 4.04% higher than the RDW of SC704. At maturity, the proportions of RDW at soil depths of 0–10, 10–20, 20–40, and 40–60 cm were 61.40%, 11.19%, 17.19%, and 10.21%, respectively, for DH618, which was an average of 9.59% higher than that of SC704 over the 20–60 cm soil layer. At maturity, DH618 roots were mainly distributed in the narrow rows, accounting for 72.03% of the root structure; this was 9.53% higher than the roots of SC704. At silking and maturity, the root weight densities of DH618 were 471.98 g m−3 and 382.98 g m−3, respectively (5.18% and 5.97% higher, respectively, than the root weight densities of SC704). The root lengths of DH618 were 239.72 m plant−1 and 199.04 m plant−1 at the silking and maturity stages, respectively; these were 16.45% and 25.39% higher, respectively, than the root lengths of SC704. The root length densities were 0.58 cm cm−3 and 0.46 cm cm−3 at the silking and maturity stages, respectively, and these were 16.86% and 17.08% higher, respectively, than the root length densities of SC704. This study indicated that the maize hybrid DH618 had a more developed root structure with increased root distribution in the deep soil and narrow rows under high-density planting compared to cultivar SC704, contributing to high grain yield under dense planting.

Density‐dependent and independent mechanisms jointly reduce species performance under nitrogen enrichment

Nitrogen (N) deposition is a primary driver of species loss in plant communities globally. However, the mechanisms by which high N availability causes species loss remain unclear. Many hypotheses for species loss with increasing N availability highlight density‐dependent mechanisms, i.e. changes in species interactions. However, an alternative set of hypotheses highlights density‐independent detrimental effects of nitrogen (e.g. N toxicity). We tested the role of density‐dependent and density‐independent mechanisms in reducing species performance. For this aim, we used 120 experimental plant communities (mesocosms) comprised of annual species growing together in containers under four fertilization treatments: 1) no nutrient addition (control), 2) all nutrients except N (P, K, and micronutrients), 3) low N (3 gN m−2) + other nutrients, and 4) high N (15 gN m−2) + other nutrients. Each fertilization treatment included two sowing densities to differentiate between the effects of competition (N × density interactions) and other detrimental effects of N. We focused on three performance attributes: the probability of reaching the reproduction period, biomass growth, and population growth. We found that individual biomass and population growth rates decreased with increasing sowing density in all nutrient treatments, implying that species interactions were predominantly negative. The common grass Avena barbata had a higher biomass and population growth under N enrichment, regardless of sowing density. In contrast, the legume Trifolium purpureum showed a density‐independent reduction in biomass growth with increasing N. Lastly, the small forb Silene palaestina showed a density‐dependent reduction in population growth, i.e. the decline occurred only under high density. Our results demonstrate that density‐dependent and density‐independent mechanisms operate simultaneously to reduce species performance under high N availability. Yet, their relative importance varies among species and life stages.

Plant Architecture Influences the Population Transpiration and Canopy Temperature in Winter Wheat Genotypes

To study how plant architecture affects the canopy traits and water use of wheat, the Triticum aestivum L. population is expected to provide important information for cultivar improvement and the ideal population structure establishment for conserving water without causing an enormous grain yield loss. This study was conducted for three consecutive growing seasons using two genotypes with contrasting plant architectures as the materials, the upright-leafed compact type Jing 411 and the flat-leafed loose type Jinmai 47. The population-scale transpiration (PT) and soil evaporation (E) were partitioned from the evapotranspiration (ET) using micro-lysimeters, and the canopy traits population density and the canopy temperature depression (CTD) were also monitored during the period from the jointing to early grain filling stage—the largest water requirement period of wheat crops. Jinmai 47 showed a lower E than Jing 411, but a similar PT and ET, though it had a higher population density at the sowing density. The total evapotranspiration (TET) for the whole growing season was also similar in the two genotypes. This indicated that Jinmai 47 performed better in water conservation than Jing 411. With a similar PT and TET, however, Jinmai 47 showed a rather larger CTD and a significantly higher grain yield than Jing 411. If the higher population density and higher leaf net photosynthetic rate could explain its higher grain yield, the higher leaf stomotal conductance and transpiration rate and the higher population density could not explain the similar PT, ET and TET to Jing 411. Presumably, the involvement of the plant architecture disrupted the original higher transpiration–larger CTD relation, and broke up the prevailing saving water-losing yield concept. Thus, the study might suggest the important water saving value of the flat-leafed loose architecture in wheat crops and demonstrate the possibility of conserving irrigation water without causing serious grain yield loss by taking advantage of the distinct plant architecture to establish an appropriate population structure.

The impact of spring wheat species and sowing density on soil biochemical properties, content of secondary plant metabolites and the presence of Oulema ssp.

The physical and chemical properties of the soil are important factors influencing the yield of crops. One of the agrotechnical factors influencing the biochemical properties of soil is sowing density. It affects the yield components, light, moisture and thermal conditions in the canopy and the pressure of pests. Secondary metabolites, many of which are known to act as a defense mechanism against insects, are of importance in the interaction between the crop and abiotic and biotic factors of the habitat. To the best of our knowledge, the studies conducted so far do not sufficiently reveal the impacts of the wheat species and the sowing density, together with the biochemical properties of the soil, on the accumulation of bioactive ingredients in the crop plants, and the subsequent impacts on the occurrence of phytophagic entomofauna in various management systems. Explaining these processes creates an opportunity for more sustainable development of agriculture. The study aimed to determine the effect of wheat species and sowing density on the biochemical properties of the soil, concentrations of biologically active compounds in the plant and the occurrence of insect pests in organic (OPS) and conventional (CPS) production systems. The research was conducted on spring wheat species (Indian dwarf wheat-Triticum sphaerococcum Percival and Persian wheat-Triticum persicum Vavilov) grown in OPS and CPS at sowing densities 400, 500, 600 (seeds m-2). The following analyzes were performed: (i) soil analysis: the activity of catalases (CAT), dehydrogenases (DEH), peroxidases (PER); (ii) plant analysis: total phenolic compounds (TP), chlorogenic acid (CA), antioxidant capacity (FRAP); (iii) entomological analysis of the number of insects-Oulema spp. adults and larvae. Performing analyzes in such a wide (interdisciplinary) scope will allow for a comprehensive understanding of the soil-plant-insect biological transformation evaluation. Our results showed that an increase in soil enzyme activity caused a decrease in TP contents in the wheat grown the OPS. Despite this, both the content of TP and the anti-oxidative activity of the ferric reducing ability of plasma (FRAP) were higher in these wheats. Bioactive compound contents and FRAP were most favoured by the lowest sowing density. Regardless of the production system, the occurrence of the Oulema spp. adults on T. sphaerococcum was the lowest at a sowing density of 500 seeds m-2. The occurrence of this pest's larvae was lowest at a sowing density of 400 seeds m-2. Research on bioactive compounds in plants, biochemical properties of soil and the occurrence of pests make it possible to comprehensively assess the impact of the sowing density of ancient wheat in the ecological and conventional production system, which is necessary for the development of environmentally sustainable agriculture.

ОСОБЛИВОСТІ РОСТУ ТА РОЗВИТКУ СОРТІВ НУТУ ЗВИЧАЙНОГО ЗАЛЕЖНО ВІД ВНЕСЕННЯ МАКРО- Й МІКРОДОБРИВ

Встановлено, що за проведення позакореневого підживлення мікродобривами у фазі інтенсивного росту й розвитку рослин та, можливо, на початку бутонізації на тлі передпосівного внесення мінеральних добрив тривалість міжфазного періоду нуту від повних сходів до повної стиглості зерна коливалася в межах 89–95 діб, або збільшилася на 4–6 діб порівняно з контролем за нерівномірного вологозабезпечення та зміни температурного режиму в період вегетації. Таким чином, позакореневе внесення бору та молібдену підвищувало енергію проростання насіння нуту і його схожість, а також сприяло збереженню рослин у комплексі з позакореневим підживленням упродовж усього періоду вегетації порівняно з контролем без передпосівного внесення мінеральних добрив.

Increasing Millet Planting Density with Appropriate Fertilizer to Enhance Productivity and System Resilience in Senegal

Climate forecasts show increased frequency and intensity of drought in the semi-arid regions of west Africa, which negatively impacts food and nutrition security. Developing and improving resilient cropping systems will require adequate varieties with improved agronomic practices. The purpose of the study was to evaluate grain and biomass production of newly released dual-purpose millet varieties under different fertilizer rates and planting densities across the millet-cropping regions of Senegal with different rainfall regimes (Bambey: 600 mm, Boulel: 700 mm, Nioro: 650 mm, and Sinthiou Malème: 800 mm). The experimental design was a split-split-plot with three replicates using one traditional variety (Souna 3) and four dual-purpose varieties (Thialack 2, SL28, SL 169, and SL423) as the main factor; two planting densities (E1: 12,500 seed hills ha−1 and E2: 25,000 seed hills ha−1) as second factor; and eight fertilizer combination as sub-sub-plots. Results showed that variety yield response differed with environments. Regardless of variety, increasing sowing density increased grain yields (1600 kg ha−1 for E2 vs. 1000 kg ha−1 for E1) and fodder yields (4200 kg ha−1 for E2 vs. 3100 kg ha−1 for E1). Fertilizer response differed between environments, but the application of 70N–10P–19K + 2.5 t ha−1 cow manure produced appreciable yields in all the environments. The dual-purpose varieties (SL 28, SL 169, and Thialack 2) sown at E2 produced the best grain and fodder yields. Soil water content was greater for all varieties (Thialack 2: 12.32%; Souna 3: 5.32%; SL28: 6.32%; and SL423: 9.23%) at higher planting density compared with normal density (Thialack 2: 9.25%; Souna 3: 3.21%; SL28: 5.43%; and SL423: 7.47%). The highest agronomic-use efficiency (AEg) of inorganic fertilizer applied was observed at 25,000 seed hill ha−1 and averaged 6.63 kg kg−1 at Boulel, 9.20 kg kg−1 at Sinthiou Malème, 4.67 kg kg−1 at Bambey, and 8.32 at Nioro kg kg−1. The AEg significantly varied among fertilizer combinations, with greatest AEg obtained with 70N–22.5P–22.5K (5.53 kg kg−1) at Boulel and with 95N–17P–27K (4.66 kg kg−1) at Bambey. This study provides crop-management options for millet-cropping systems in the semi-arid regions of west Africa for improving millet productivity while enhancing system resilience through better conservation and utilizing of soil water.

Modelling Winter Rapeseed (Brassica napus L.) Growth and Yield under Different Sowing Dates and Densities Using AquaCrop Model

The sowing date and density are considered to be the main factors affecting crop yield. The determination of the sowing date and sowing density, however, is fraught with uncertainty due to the influence of climatic conditions, topography, variety and other factors. Therefore, it is necessary to find a comprehensive consideration of these factors to guide the production of winter rapeseed. A reliable crop model could be a crucial tool to investigate the response of rapeseed growth to changes in the sowing date and density. At present, few studies related to rapeseed model simulation have been reported, especially in the comprehensive evaluation of the effects of sowing date and density factors on rapeseed development and production. This study aimed to evaluate the performance of the AquaCrop model for winter rapeseed development and yield simulation under various sowing dates and densities, and to optimize the sowing date and density for agricultural high-efficient production in the Jianghuai Plain. Two years of experiments were carried out in the rapeseed growing season in 2020 and 2021. The model parameters were fully calibrated and the simulation performances in different treatments of sowing dates and densities were evaluated. The results indicated that the capability of the AquaCrop model to interpret crop development for different sowing dates was superior to that of sowing densities. For rapeseed canopy development, the RMSE for three sowing dates and densities scenarios were 7–22% and 16–23%, respectively. The simulated biomass and grain yield for different sowing dates treatments (RMSE: 0.8–2.1 t·ha−1, Pe: 0–35.3%) were generally better than those of different densities treatments (RMSE: 0.7–3.9 t·ha−1, Pe: 8.2–90%). Compared with other sowing densities, higher overestimation errors of the biomass and yield were observed for the low-density treatment. Adequate agreement for crop evapotranspiration simulation was achieved, with an R2 of 0.79 and RMSE of 26 mm. Combining the simulation results and field data, the optimal sowing scheme for achieving a steadily high yield in the Jianghuai Plain of east China was determined to be sowing in October and a sowing density of 25.0–37.5 plant·m−2. The study demonstrates the great potential of the AquaCrop model to optimize rapeseed sowing patterns and provides a technical means guidance for the formulation of local winter rapeseed production.