Optimum Plant Density Research Articles

Study on Effect of Spacing and Nutrient Management in Cabbage Cultivation in Medium Land Situation of East Medinipur

Background: Cabbage (Brassica oleracea var. capitate L.) is a nutritionally and economically high-value leafy vegetable. Therefore, the optimum plant density and the judicious application of fertilizers with organic supplements must be ensured to achieve the desired quality and quantity of cabbage. Methods: A field experiment was conducted in farmers’ field to study the effect of spacing and nutrient management on the growth, yield and economics of cabbage in East Medinipur’s medium land situation under the lower Gangetic plain of West Bengal during the Rabi season in 2020. Three technology options with three distinct spacing (TO-I: 60 × 30 cm2 + RDF, TO-II: 60 × 45 cm2 + RDF and TO-III: 60 × 60 cm2 + RDF) along with one farmer’s practice (FP: Random spacing and fertilization) were evaluated using randomized block design (RBD). Result: The findings showed that the maximum plant height (37.2 cm), the lowest number of aberrant heads (7.81%) and the highest individual head weight (1.89 kg) were recorded in TO-III. Individual head weight was decreased in the following order: TO-III greater than TO-II greater than TO-I greater than FP. Though TO-I recorded the maximum harvestable (59.45 t/ha) and marketable yield (53.28 t/ha), TO-II had the maximum net return (Rs. 237069 ha-1) and the highest benefit-cost ratio (2.78). In contrast, the lowest net return (Rs. 112115 ha-1) and benefit-cost ratio (1.81) were recorded in FP. The decreasing order of net return, as well as the benefit-cost ratio, was found to be: TO-II greater than TO-III greater than TO-I greater than FP.

Değişik Bitki Sıklıklarının Tek ve Çift Sıralı Ekimlerde Hibrit Mısırın (Zea Mays L.), Büyüme ve Verim Özelliklerine Etkisi

This research was conducted to compare single and twin-row planting patterns and to determine optimum plant density for hybrid maize varieties (DKC5364, P0573), grown in Western Blacksee conditions of Türkiye, in the main crop growing season in 2020. The experimental design was a randomized complete block in a split-split plot arrangement with three replications. Hybrid maize varieties were in the main plots, planting patterns (single row (70 cm) and twin row (70-20cm) were in the split plots and plant densities of 8, 9, 10, 11 and 12 plants/m2 were in the split- split plots. In the current study, plant height, first ear height, stem diameter, ears number per plant, ear length, ear diameter, and ear weigth were examined. Effects of varieties, planting patterns and plant densities on plant heights, first ear heights, ears numbers per plants and ear weigths were statistically significant. Higher values were observed at DKC5364 maize variety than P0573 variety for examined characteristics. The most suitable plant densities were determined as 11 plants/m2 for grain production and 12 plants/m2 for silage production in twin row plantig in Western Blacksee conditions of Türkiye

Physiological responses, yield and medicinal substance (andrographolide, AP1) accumulation of Andrographis paniculata (Burm. f) in response to plant density under controlled environmental conditions.

Agricultural practice in adjusting planting density and harvest date are important factors for plant development and crop improvement, reaching maximum yields and enhancing the production of secondary metabolites. However, it is unclear as to the optimal planting densities during mass production that encourage consistent, high yield secondary metabolite content. For this, controlled environment, crop production facilities such as plant factories with artificial lighting (PFAL) offer opportunity to enhance quality and stabilize production of herbal plants. This study assessed the effect of plant density and harvest date on physiological responses, yield and andrographolide (AP1) content in Andrographis paniculata (Andrographis) using hydroponic conditions in a PFAL system. Andrographis, harvested at vegetative stage (30 days after transplanting; 30 DAT) and initial stage of flowering (60 DAT) exhibited no significant differences in growth parameters or andrographolide accumulation according to planting densities. Harvest time at flowering stage (90 DAT) showed the highest photosynthetic rates at a planting density of 15 plants m-2. Highest yield, number of leaves, and Andrographolide (AP1) content (mg per gram of DW in m2) were achieved at a more moderate planting density (30 plants m-2). Finally, five out of seventeen indices of leaf reflectance reveal high correlation (r = 0.8 to 1.0 and r = -0.8 to -1.0, P<0.01) with AP1 content. These results suggest that a planting density of 30 plants m-2 and harvest time of 90 DAT provide optimal growing condition under the hydroponic PFAL system.

Enhancing maize yield in Ethiopia a meta-analysis

Accurate nitrogen (N) fertilization and optimum plant density increase crop yields. In this study, I report the effects of N fertilization rate and plant density on maize yield in a meta-analysis, by using observations from 15 studies conducted in Ethiopia since the 2000s for possible refinement of N fertilizer and plant density recommendations. I assessed the response of maize to different N rates ha−1 compared to the control using the yield response approach. Application of N fertilizer significantly increased maize yields by 31.5% - 65.9% compared to control. plant density increased maize yields by 42% - 72.4% compared to the control. The interaction effect of the N rate increased maize yields by 27.6% - 95.9%, with Plant density, 58.7% - 152% on loam soil, compared to control yield. The interaction effect of Plant density with soil type increased maize yields by 47% - 108% on loam soil. In conclusion, the grain yield of maize increased with increasing N rate and plant density up to the optimum. Therefore, it’s possible to recommend using a high N rate with both low and medium plant density (&lt; 45,000 plants ha-1) and (45,000 to 65,000plants ha-1) to harvest high grain yield.

Mathematics of the Relationship between Plant Population and Individual Production of Maize (Zea mays L.)

Predominantly, field experiments aim to determine the optimal plant density for a unit area. High spatial variation results in lower attained yield than the genetic potential. To find the highest value of the product of mean individual production and crop density, their mathematical relationship is needed to be known. In this study, the relationship between the population and the weight of the individual fresh, dehusked ear of grain maize (Zea mays L.) was investigated, and a relevant mathematical simulation model was developed. Linear regression was disproved to describe this relationship properly based on the analysis of different mosaic sizes within a plot. The distribution of plant-to-plant distance was found to be binomial. The distribution of the ear weight was found to be lognormal. For the description of the population homogeneity, neither the standard deviation nor the variation coefficient was found to be applicable apart from the scale-independent relative variance. The simulation model, based on the above statistical functions, was validated with a real dataset, and it is recommended for the optimization of the plant population at farm scale.

Optimum Plant Density for Increased Groundnut Pod Yield and Economic Benefits in the Semi-Arid Tropics of West Africa

Groundnut is a very important crop in the West and Central Africa (WCA) region, accounting for almost 70% of Africa’s groundnut production in 2019. Despite its economic importance, the crop’s yield is still low. For a high yield and profitable economic returns, optimal plant density is a fundamental crop management practice. Plant density experiments were conducted at the ICRISAT-Mali research station between 2016 and 2021 over the main rainy and dry seasons to determine the optimum density for maximum groundnut yield and economic benefits. The treatments contained row spacing of 20 cm, 30 cm, 40 cm, 50 cm, 60 cm, 70 cm, 80 cm, 90 cm, and 100 cm, with intra-row spacing of 10 cm, 15 cm, and 20 cm. Results showed that when plant density was increased, dry pod yield, production value, and net economic benefit per hectare increased in a no moisture stress scenario. During the rainy season, the 40 cm × 10 cm spacing gave the highest dry pod yield (1693 kg), production value ($891.6), and net benefit ($403.5) per hectare. The highest dry pod yield (3703 kg), production value ($2173), and net benefit ($1510.2) per hectare were obtained from 30 cm × 10 cm spacing during the dry season. The number of pods per plant and 100 SW increased with lower plant densities. Therefore, it is recommended to increase plant density to at least 222,000 plants per hectare in the Sudan Savannah agroecology of WCA.

Optimizing plant density and balancing NPK inputs in combination with innovative fertilizer product for sustainable maize production in North China Plain

Excessive NPK inputs but low grain yield and high environmental impact are common issues in maize production in North China Plain (NCP). The objective of our study was to test whether a combined strategy of optimizing plant density, balancing NPK input, and innovating one-time fertilizer products could achieve a more sustainable maize production in NCP. Thus, a field experiment was conducted at Luanna County NCP with the treatments of unfertilized control (CK), farmer practice (FP, conventional plant density and NPK input), conventional one-time urea-based coated fertilizer (CF, optimized plant density and NPK input), and five newly designed innovative one-time NPK fertilizers of ammonium sulphate and urea synergy (IF, optimized plant density and NPK input), innovative fertilizer with various additives of urea inhibitors (IF + UI), double inhibitors (IF + DI), micro-organisms (IF + MI), and trace elements (IF + TE). The grain yield, N sustainability indicators (N use efficiency NUE, partial factor productivity of N PFPN, and N surplus), and cost-benefits analysis were examined over the maize growing season of 2020. Results had shown that on average the five innovative fertilizers (IF, IF + UI, IF + DI, IF + MI, and IF + TE) and CF that had optimized plant density and NPK input achieved 13.5%, 98.6%, 105.9%, 37.4% higher yield, PFPN, NUE, net-benefits as well as 207.1% lower N surplus compared with FP respectively. Notably, the innovative fertilizer with various effective additives (IF + UI, IF + DI, IF + MI, and IF + TE) which can be commonly found in the fertilizer market hadn’t resulted in a significant improvement in yield and NUE rather a greater cost and lower net benefits in comparison to IF. In summary, our study highlighted the effectiveness of the combined strategy of optimized plant density, balancing NPK input, and innovative NPK fertiliser on sustainable maize production in NCP, however, the innovative fertilisers with effective additives should be properly selected for better economic benefits.

Optimizing planting density and irrigation depth of hybrid maize seed production under limited water availability

Improvement in seed vigor and yield of hybrid maize is required to ensure food security. Optimal planting density and irrigation depth are critical for hybrid maize seed production in arid areas. Using data from 2012 to 2017, a new integrated model optimized planting density and border irrigation depth for achieving high yield and seed vigor of hybrid maize under limited water availability. For field experiments, a planting density of 9.75 plants m−2 under full irrigation was in the control treatment. The results showed that water deficit decreased yield, evapotranspiration, and aboveground biomass per plant. The highest yield was obtained for the planting density of 12.75 plants m−2 under full irrigation. The single crop coefficient and crop water production function models were modified to simulate evapotranspiration and yield, respectively. Using kernel number per plant and plant growth rate during the flowering stage, a kernel weight model was established. The maximum yield and minimum irrigation depth were weighted and kernel weight was constrained. Three minimum relative kernel weight (RKWmin) options were considered, option 1 with RKWmin= 1.00 (control), option 2 with RKWmin= 0 (unconstrained), and option 3 with RKWmin ranged from 0.60 to 0.90. In option 1, the optimal irrigation depth during the growing season under control planting density decreased by 24.3–39.4% compared to the conventional practices. In option 2, yield increased but average kernel weight decreased by 25% than control. In the option 3, average yield and water use efficiency increased by 9.2% and 6.5% compared to option 1, respectively. The average planting density decreased by 10.2%, yield reduced by 2.0%, and water use efficiency reduced by 1.7%, but kernel weight increased by 9% compared to option 2. Thus option 3 can be recommended for hybrid maize seed production with limited water availability in arid regions of Northwest China. Our research provided a new theoretical method to improve yield, and ensure seed vigor of hybrid maize in arid regions.

Effects of N fertilizer rate and planting density on short-season cotton yield, N agronomic efficiency and soil N using 15N tracing technique

Straw returning has been widely used as a nitrogen (N) reduction measure in the North China Plain in recent years. However, little is known of the optimal planting density and N application rate of cotton under straw returning. In order to study the effect of the planting density and N application rate on cotton yield, nitrogen agronomic efficiency (NAE), fertilizer N recovery efficiency (FNRE), N balance and soil N under straw returning, a split-plot design in randomized complete blocks was used in the experiment. The main plots were assigned to plant densities (4.50 × 104, 6.75 × 104 and 9.00 × 104 plants hm−2), and the subplots to N application rates (0, 180, 225 and 270 kg N hm−2). The results showed that the biological yield increased as the planting density and the N application rate increase, but the harvest index decreased. Therefore, the highest biological yield was found under D9.00N270, but the highest cotton yield was found under D6.75N225. Excessive N (N270) application rate was not conducive to the improvement of NAE and FNRE. The amounts of plant N derived from fertilizer (Ndff) was reduced with the increase of planting density. Therefore, soil N would be consumed because the N balance was a negative value when N application rate was decreased at N180, especially at high density. The N balance was closest to zero at D6.75N225. In summary, with the yield, NAE, FNRE, N balance and the stability of soil N taken into consideration, the optimal combination of planting density and N application rate in the North China Plain was D6.75N225, because this treatment had the highest cotton yield, and most importantly, it maintained sustainable cotton production in the field.

Long-Term Optimal Management of Rapeseed Cultivation Simulated with the CROPGRO-Canola Model

Rapeseed (Brassica napus L.) is an important oilseed crop grown worldwide with a planting area of 6.57 million ha in China, which accounts for about 20% of the world’s total rapeseed planting area. However, in recent years, the planting area in China has decreased by approximately 12.2% due to the low yield and economic benefits. Thus, to ensure oil security, it is necessary to develop high-efficiency cultivation for rapeseed production. Crop growth models are powerful tools to analyze and optimize the yield composition of crops under certain environmental and management conditions. In this study, the CROPGRO-Canola model was first calibrated and evaluated using the rapeseed planting data of four growing seasons in Wuhan with nine nitrogen fertilizer levels (from 120 to 360 kg ha−1) and five planting densities (from 15 to 75 plants m−2). The results indicated that the CROPGRO-Canola model simulated rapeseed growth well under different nitrogen rates and planting densities in China, with a simulation error of 0–3 days for the anthesis and maturity dates and a normalized root mean square error lower than 7.48% for the yield. Furthermore, we optimized the management of rapeseed by calculating the marginal net return under 10 nitrogen rates (from 0 to 360 kg ha−1 at an increasing rate of 40 kg ha−1) and 6 planting densities (from 15 to 90 plant m−2 at an increasing rate of 15 plant m−2) from 1989 to 2019. The results indicated that the long-term optimal nitrogen rate was 120–160 kg N ha−1, and the optimal planting density was 45–75 plants m−2 under normal fertilizer prices. The optimal nitrogen rate decreased with increasing fertilizer price within a reasonable range. In conclusion, long-term rapeseed management can be optimized based on rapeseed and nitrogen cost using long-term weather records and local soil information.

Сопряженность семенной продуктивности клевера лугового с полеганием травостоя

Analysis of the problems of increasing the yield of clover seeds shows that, in relation to fodder perennial grasses, the tasks of selection when breeding new varieties are associated with improving the vegetative development of plants. Fodder use provides for the need to further increase the productivity of phytomass, increase the period of active shoot formation, the predominance of vegetative stems in the structure of the herbage, and others. Such natural or selectively induced features of plant development make it difficult to sow varieties for fodder purposes. The growth and development of red clover, the yield value is greatly influenced by the biological characteristics of varieties, as well as agrometeorological conditions during the formation of generative organs, flowering, seed setting and filling. One of the main factors influencing the yield value is the lodging of the herbage. In modern varieties of meadow clover of an intensive type, during the process of growth and accumulation of vegetative mass, lodging of grass stands of varying degrees is usually observed already by the flowering phase, which negatively affects the formation of seed productivity. The purpose of the research is to study the effect of grass stand lodging on the realization of the seed productivity potential of red clover varieties of early and late ripening types. To solve this problem, vertical clover shoots were artificially formed using a special frame. The degree of lodging of seed grass stands of late-ripening clover under field conditions was 56%, and that of early-ripening clover was 36–39%. With the artificial creation of non-lodging grass stands compared to lodging ones, depending on the prevailing weather conditions, the biological yield of meadow clover seeds of late-ripening type increased by 88%, and in early-ripening — in the range from 31 to 48% due to an increase in the number of inflorescences by 14–27% and seeds in heads by 14–28%. To increase the yield of meadow clover seeds, it is necessary to develop and use a complex of agrotechnical techniques that ensure the formation of non-lodging grass stands with optimal plant density per unit area.

Nitrogen-Reduction in Intensive Cultivation Improved Nitrogen Fertilizer Utilization Efficiency and Soil Nitrogen Mineralization of Double-Cropped Rice

Under the current rice cropping system, excessive nitrogen application has become a major issue that needs to be changed, and nitrogen reduction has become a hot research topic in recent years. The use of optimum planting density is becoming a common agronomic management system in addition to nitrogen reduction, especially under double cropping rice systems. In this paper, changes in rice yield, nitrogen-use efficiency (NUE) and net N mineralization under dense planting with a reduced nitrogen rate (DPRN) were studied. By comparing DPRN with high-nitrogen sparse planting (SPHN), we found that the population tiller number (tiller number per unit area) increased by 9–27% under DPRN cultivation. Nitrogen accumulation under DPRN treatment of double-cropped rice was basically stable. NUE under DPRN was significantly higher by 1.3–22.7% compared to SPHN. The partial factor productivity of applied N (PFPN) was significantly higher than that of SPHN, with an increase of 4.3–22.8%. The net N mineralized of double-cropped rice under DPRN increased at different stages, and the increase in late-season rice (LSR) was greater than that of early-season rice (ESR). The highest net N mineralized in double cropping rice at different stages was found in the dense planting treatment (DP) and N2 (120 kg N h−1). In conclusion, DPRN cultivation of double-cropped rice could be accepted as a proper management strategy for reducing nitrogen input, improving NUE and promoting soil nitrogen mineralization under given conditions.

Light Interception, Photosynthetic Performance, and Yield of Oil Palm Interspecific OxG Hybrid (Elaeis oleifera (Kunth) Cortés x Elaeis guineensis Jacq.) under Three Planting Densities.

Environmental conditions are crucial for crops’ growth, development, and productivity. One of the most important physiological factors associated with the production of crops is the use of solar radiation for the photosynthesis process, which determines the amount of assimilates available for crop growth and yield. Three age classes (4, 6, and 14 years) and three planting densities (143, 128, and 115 palms ha−1) were evaluated in a commercial interspecific Elaeis Oleifera x Elaeis guineensis hybrid Coari x La Mé. The light interception patterns and the photosynthetic performance were determined. Measurements were taken of the leaf area, the number of leaves, and incident and photosynthetically transmitted active radiation. Also, photosynthetic rates, light, and yield were measured. The canopy extinction coefficient (Kc) was estimated using the Monsi and Saeki model. Under the evaluated conditions, the average Kc value for 4-year-old palms was 0.44; for the 6-year-old group of palms, the average value was 0.40, and 0.32 for the 14-year-old palms, with coefficients of determination (R2) greater than 0.8. A pattern associated with the age of the crop was observed, where the Kc decreased in groups of adult palms. The results showed increased Kc as the planting density decreased. No statistically significant differences were observed between planting densities or ages in the light and CO2 curves regarding photosynthesis. The leaf level in which the measurement was made influenced photosynthesis. Thus, the highest values of the photosynthesis parameters were observed in leaf 17. The crop yield tended to stabilize 8 years after planting under 143 and 128 palms per hectare, but 14 years after planting, the Fresh fruit bunch (FFB) production was still growing under 115 palms per hectare. The results showed that, up to year 14 after planting, the highest cumulative yield was achieved with 115 palms per hectare. This was partly caused by a sharp decline in production observed under 128 palms per hectare, which could indicate that in the long production cycle of the OxG hybrids, the 115-palms-per-hectare planting density would result in higher cumulative FFB production. Furthermore, the results showed that the optimum planting density for the hybrids of the present study would be 120 palms ha−1, corresponding to a planting distance of 9.8 m between plants.

Optimum Stand Density of Tropical Maize Varieties: An On-farm Evaluation of Grain Yield Responses in the Nigerian Savanna

Selection of appropriate sowing density is an important yield enhancing management decision in maize (Zea mays L.) production particularly in rainfed conditions. This study aimed at evaluating the optimum stand densities (OSDs) of 10 recently released maize varieties under different crop management decisions and environments. Ten maize varieties of varying characteristics were planted in the Northern Guinea Savanna of Nigeria across 30 farmer's fields in the rainy seasons of 2016 and 2017 under three stand densities: 2.6, 5.3, and 6.6 plants m−2. Grain yield and yield components were greatest under the high density in both years across all locations. The intermediate maturing varieties produced higher grain yields compared to the early and late maturing varieties in both years and locations. The environmental indices from the Factor Analytic Model showed 20% of the fields were optimal, 28.3% moderate, 31.7% poor, and 20% were very poor environments. Increasing planting density did not significantly affect the grain yield of the varieties in very poor environments. A linear increase in grain yield was observed in moderate and optimum environments with every increase in stand density for all varieties except Sammaz 32, however, optimum planting densities could not be reached for all the varieties. Therefore, tropical maize varieties should be planted under specific densities that account for environmental and management conditions to maximize yield.

Close‐spaced plant arrangement optimizes castor biomass and seed yields in tropical fall–winter conditions

AbstractThe high seed yield and optimum harvesting of short‐height castor (Ricinus communis L.) genotypes have enabled its large‐scale cultivation and introduction in the Brazilian cropping systems. Thus, studies to optimize plant density are essential to adequate plant population since this is the key management to influence castor biomass and seed production. This study aimed to evaluate the influence of plant density by altering plant arrangement (i.e., spacing between and within rows) on growth, biomass production and partitioning, and seed yield of a castor cultivar in fall–winter cropping season. Field experiments were conducted over two seasons in southeastern Brazil. Two close‐spaced (0.45 × 0.23 m and 0.45 × 0.44 m) and a traditional (0.90 × 0.44 m) plant arrangements were tested. Plant arrangements influenced plant growth, biomass production and partitioning, and seed yield. Compared to the traditional layout, close‐spaced plant arrangements resulted in thinner basal stems and lower leaf area per plant, but increased leaf area index. The plant arrangement with higher plant density increased per‐unit area production of stem plus leaf biomass (43–48%), which also resulted in increased (24%) seed yield, compared to traditional layout. Although a greater amount of biomass was partitioned to reproductive organs in close‐spaced plant arrangements, this allocation was not enough to influence the harvest index. Therefore, the adaptive performance of short‐height castor adjusting biomass partitioning to maximize stem plus leaf biomass production and seed yield at close‐spaced plant arrangement demonstrated this to be a suitable option to cultivate in the Brazilian fall–winter season.

Overview of the advantages and limitations of maize-soybean intercropping in sustainable agriculture and future prospects: A review

Intercropping has benefited the global agricultural sector in several ways. It is a critical farming practice for long-term productivity, agro-ecological improvement, land management, and land use. It is a well-known method to increase soil health and crop productivity. The impact of intercropping on the yield and production of maize (Zea mays L.) and soybean (Glycine max (L.) Merr.) has been investigated at the leaf, stem, and root level. However, there is limited information about how to determine the best planting density for maize-soybean intercropping (MSI). The benefits and drawbacks of MSI are discussed in this review. Intercropping maize and soybean improves resource use, lodging resistance, and pest and weed control according to the existing research. Furthermore, soybean has low light use efficiency (LUE) and radiation use efficiency (RUE) due to the deep shade created by the maize canopy. As a result, more research is required to discover the optimal planting density to improve light and radiation efficiency.

Effect of Population Density and Fertilizer Rates on Yield and Yield Components of High Land Maize

A field experiment was conducted for two years (2019 and 2020) during the main cropping seasons at Holeta, Welmera wereda, West Shoa, in the central highlands of Ethiopia to determine optimum planting density and fertilizer rates for maize production. The treatments consists of factorial combination of four population densities (44,444, 53,333, 62,500 and 66,666 plants/hectare) and four fertilizer rates (150:200,150:250, 200:200 and 250:200 NPS:Urea kg/ha) laid down in a randomized complete block design (RCBD) with three replications. The main effect of population density significantly (P &lt; 0.05) affected plant height, ear height, cob diameter and grain yield but not significantly affected cob length, number of cob per plant and thousand seed weight. Even if the main effect of population density did not significantly affect thousand seed weight, the lowest thousand seed weight was recorded at the highest population density. The main effect of fertilizer rates significantly (P &lt; 0.05) affected only plant height and grain yield. As population density increases maize grain yield was also increasing, and the highest grain yield (8894.2kg/ha) was attained by the highest population density (66,666plants/ha). This means that population density more than 66,666plants /ha may be needed because the grain yield was still in increasing manner. On the other hand, the interaction effect of population density and fertilizer rates was not significant to affect all the tasted growth and yield parameters. Based on statistical and economic analysis results, out of the tasted treatments the highest grain yield was recorded at the highest population density (66,666plants/ha) and using fertilizer rate of 250NPS:200Urea. Keywords: highland maize, population density, fertilizer rate, yield DOI: 10.7176/JNSR/13-3-03 Publication date: February 28 th 2022

Complex plant interactions in heterogeneous material require the ecological rethinking of sowing density recommendations for bread wheat. A review

Des pite the growing concerns over the damages and unsustainability of conventional agriculture, arable farmers struggle to convert to organic cropping practices. In wheat farming, the lack of cultivars adapted to organic cropping has prompted a search for alternatives to better cope with unpredictability and stress. In that respect, heterogeneous material (HM) has attracted a lot of attention for its good performances and yield stability across years and environments. These benefits are thought to arise from facilitative plant interactions brought forth by intraspecific diversity, but much remains to be known about the mechanisms at play as well as their interactions with the other elements of the cropping system. Here, we review the literature on plant interactions within organic bread wheat crops through the successive scopes of (i) heterogeneous material, (ii) plant density, and (iii) their interaction. Our major findings are as follows: (1) optimizing heterogeneous material performance and evolutionary trajectories grossly amounts to tipping the balance between competitive and facilitative plant interactions toward the latter. (2) The stress gradient hypothesis applies to the competition/facilitation balance within HM: The more stressful the conditions, the more facilitation happens. (3) Plant density also affects this balance, and the relationship between net facilitation and plant density in HM follows a humped curve. (4) Therefore, the optimal plant density range for HM should be both narrower and lower than for pure lines, and also harder to predict. (5) High-tillering, high individual yielding plant types should probably be aimed for in HM, for two reasons: first, they perform better at the lower-than-the-recommendations plant densities at which HM are expected to best express their potential. Second, optimal plant densities of such plant types are more stable across environments, which should increase the probability of falling within the narrower optimal plant density range of HM, particularly in unpredictable and/or stressed environments.

Technological factors in the cultivation of sterlet sturgeon planting material in a recirculation aquaculture system

Recently, it has not been possible to engage in natural reproduction of sturgeons in Dagestan, because the spawning rivers Terek and Sulak are regulated, and the passage to the spawning grounds is completely closed by dams. There is only one way out for the restoration of sturgeon stocks it is artificial reproduction through industrialization and the creation of complex, closed regulated fish farms that can function both in the form of small fish farms and in the form of large holdings. The purpose of the work was to study technological factors in the cultivation of sterlet sturgeon planting material in a recirculation aquaculture system. The object of the study was a population of sterlet sturgeon (Asirepseg ruthenus Linnaeus, 1758) – a freshwater fish species of the sturgeon family. The study material was normally pigmented and albino (colored) sterlet with an average initial weight of 60 g. Under the conditions of the Republic of Dagestan studies have been carried out to establish the influence of a complex of biotic and abiotic factors (temperature, oxygen, planting density, feed grade, meat and bone attractant, probiotic Subtilis) on the growth, morphometric indicators and survival of juvenile sterlet sturgeon in the recirculation aquaculture system. The fish-breeding and biological characteristics of pigmented and albino sterlet have been given. It has been established that the design features of the recirculation aquaculture system did not allow to meet the biological needs of sterlet in water. The flow rate of water entering fish tanks was limited to 10 l/min per 1 m³, which provided a water change in 1 hour 40 minutes at a standard of 20–60 minutes. The optimal planting density of sterlet with an initial body weight of 58–64 g under conditions of limited water supply (10 l/min/m³) was the density of 250 pcs. /m³. The effectiveness of using two formulations of compound feed when growing both normally pigmented fish and their albinos showed that the highest fish-breeding indicators were obtained in normally pigmented sterlet when feeding with Sturgeon Grower No. 4 (47/13). The economic effect amounted to 373,5 rubles/m³. In albinos, the highest fish-breeding indicators were obtained when feeding productional feed Sturgeon grower 46/18 with. The economic effect was 285,0 rubles/m³.

Aerial Imagery Paddy Seedlings Inspection Using Deep Learning

In recent years complex food security issues caused by climatic changes, limitations in human labour, and increasing production costs require a strategic approach in addressing problems. The emergence of artificial intelligence due to the capability of recent advances in computing architectures could become a new alternative to existing solutions. Deep learning algorithms in computer vision for image classification and object detection can facilitate the agriculture industry, especially in paddy cultivation, to alleviate human efforts in laborious, burdensome, and repetitive tasks. Optimal planting density is a crucial factor for paddy cultivation as it will influence the quality and quantity of production. There have been several studies involving planting density using computer vision and remote sensing approaches. While most of the studies have shown promising results, they have disadvantages and show room for improvement. One of the disadvantages is that the studies aim to detect and count all the paddy seedlings to determine planting density. The defective paddy seedlings’ locations are not pointed out to help farmers during the sowing process. In this work we aimed to explore several deep convolutional neural networks (DCNN) models to determine which one performs the best for defective paddy seedling detection using aerial imagery. Thus, we evaluated the accuracy, robustness, and inference latency of one- and two-stage pretrained object detectors combined with state-of-the-art feature extractors such as EfficientNet, ResNet50, and MobilenetV2 as a backbone. We also investigated the effect of transfer learning with fine-tuning on the performance of the aforementioned pretrained models. Experimental results showed that our proposed methods were capable of detecting the defective paddy rice seedlings with the highest precision and an F1-Score of 0.83 and 0.77, respectively, using a one-stage pretrained object detector called EfficientDet-D1 EficientNet.