Increasing Plant Density Research Articles

Unveiling constraints and cultivating potential: Optimizing spring sugar beet yield through boundary line analysis

To enhance crop yields, narrowing the gap between actual and achievable yields is crucial. One approach involves identifying yield-limiting factors and their optimal levels. Boundary line analysis (BLA), a statistical method, quantifies yield response to environmental or managerial factors while accounting for variable factors. In 2020, a study surveyed 180 spring sugar beet farms in Iran. The findings revealed a 50.7 % yield gap (11.13 t ha−1) between farmers’ average sugar yield (10.84 t ha−1) and potential yield (21.97 t ha−1). BLA implicated low plant density, soil organic content, lack of potassium (K)-containing fertilizers, and non-adherence to crop rotation principles in 81.3 %, 75.5 %, 53.4 %, and 51.1 % of farms, respectively. Optimal levels were estimated at 9.5 plants m−1, 1.15 % soil organic content, 100 kg ha−1 K fertilization rate, and 5–9.8 as the rotation numerical value. Other limiting factors included time from cultivation to thinning and sowing date. The optimal minimum time between planting and thinning stood at 38 days, with the latest sowing date estimated at 94 Julian days (May 5). Achieving attainable yield necessitates limiting root exposure to 4.9 days, keeping disease damage below 15.3 %, and increasing irrigation frequency to over 10 times. In the short term, increasing plant density to optimal levels, promoting K fertilizer use, and adjusting thinning and sowing dates can significantly boost sugar yield per unit area.

Photosynthetic capacity and assimilate transport of the lower canopy influence maize yield under high planting density.

Photosynthesis is a major trait of interest for the development of high-yield crop plants. However, little is known about the effects of high-density planting on photosynthetic responses at the whole-canopy level. Using the high-yielding maize (Zea mays L.) cultivars "LY66," "MC670," and "JK968," we conducted a 2-yr field experiment to assess ear development in addition to leaf characteristics and photosynthetic parameters in each canopy layer at 4 planting densities. Increased planting density promoted high grain yield and population-scale biomass accumulation despite reduced per-plant productivity. MC670 had the strongest adaptability to high-density planting conditions. A physiological analysis showed that increased planting density primarily led to decreases in the single-leaf area above the ear for LY66 and MC670 and below the ear for JK968. Furthermore, high planting density decreased chlorophyll content and the photosynthetic rate due to decreased canopy transmission, leading to severe decreases in single-plant biomass accumulation in the lower canopy. Moreover, increased planting density improved presilking biomass transfer, especially in the lower canopy. The yield showed significant positive relationships with photosynthesis and biomass in the lower canopy, demonstrating the important contributions of these leaves to grain yield under dense planting conditions. Increased planting density led to retarded ear development as a consequence of reduced glucose and fructose contents in the ears, indicating reductions in sugar transport that were associated with limited sink organ development, reduced kernel number, and yield loss. Overall, these findings highlighted the photosynthetic capacities of the lower canopy as promising targets for improving maize yield under dense planting conditions.

Positive Correlation of Lodging Resistance and Soybean Yield under the Influence of Uniconazole

Increasing planting density is one of the most effective ways to increase soybean yield, but supra-optimum density leads to an increase in the risk of lodged soybean. In this study, two varieties were selected. Heinong84 (lodging-susceptible variety, HN84) had planting densities of 200,000 plants/hm2, 300,000 plants/hm2, and 400,000 plants/hm2. Henong60 (lodging-resistant, HN60) had planting densities of 300,000 plants/hm2, 400,000 plants/hm2, and 500,000 plants/hm2. When the foliar application of uniconazole (50 mg/L) occurred at the beginning of the flowering stage (R1), the plant morphology, fiber composition, and mechanical properties of soybean internodes were determined at the podding and seed filling stages, and the yield was measured at the harvest stage. The results showed that spraying uniconazole at the R1 stage changed the morphology structure of soybean plants (i.e., plant height and petiole length reduction; stem diameter and leafstalk angle increase), improved the internode quality (i.e., increased breaking force, lignin content, cellulose content, hemicellulose content, and stem dry weight per unit length), and increased the number of grains per plant at the harvest stage. Thus, it is concluded that the application of uniconazole improved the plant population structure by changing the morphology of soybean plants, which was conducive to good light transmission and ventilation, improved the internode quality and lodging resistance, and increased the yield.

Effect of Plant Density on Mechanical Harvest Efficiency of New Mexico Pod-type Green Chile Pepper

Summary. New Mexico green pod-type chile (Capsicum annuum) has significant importance as a vegetable crop. The cultivation and trade of New Mexico pod-type green chile are culturally significant within New Mexico (USA) and contribute to the state’s economy by providing income and employment to farmers and through supporting industries. However, because of the high cost and limited availability of labor, New Mexico pod-type green chile acreage has declined. Traditionally, New Mexico pod-type green chile is hand-harvested when the fruit are full-size but physiologically immature. To preserve and expand the production of New Mexico pod-type green chile, the adoption of mechanical harvest technologies is essential. In 2015 and 2016, experiments were conducted at New Mexico State University’s Los Lunas Agricultural Science Center (Los Lunas, NM, USA) to examine the effects of increased planting density on New Mexico pod-type green chile fruit size, plant architecture, and mechanical harvest efficiency. Two commercial New Mexico pod-type green chile cultivars, NuMex Joe E. Parker and AZ-1904, were direct-seeded on 17 Apr 2015 and 14 Apr 2016. On 11 Jun 2015 and 14 Jun 2016, three plant density treatments were implemented at 39,000 (high), 23,000 (medium), and 15,000 (standard) plants/acre. Before harvest, plant measurements, including height, width, height to first bifurcation, stem diameter, and number of lateral basal branches, were obtained. Plots were mechanically harvested using an inclined double helix harvester, and harvested material was sorted into marketable green fruit, machine-broken fruit, and nonpod plant material. Fruit measurements, including fruit weight, width, length, pericarp thickness, and number of locules, were obtained. Both cultivars exhibited a 9% increase in height to bifurcation accompanied by fewer basal branches grown at high density. Plant density did not significantly affect the fruit length, width, number of locules, and pericarp thickness. Plants grown at high density had an increased percentage of marketable fruit, with ‘NuMex Joe E. Parker’ having a higher percentage of marketable green fruit compared to ‘AZ-1904’. The results demonstrated that an increase in planting density in production fields to 39,000 plants/acre coupled with cultivar selection enhanced efficiency in a mechanical harvest system.

Optimizing nitrogen application and planting density improves yield and resource use efficiency via regulating canopy light and nitrogen distribution in rice

Coordinating light and nitrogen (N) distribution within a canopy is crucial to improve rice yield and resource use efficiency. However, little attention has been paid to light and N distribution in response to planting density and N rate, and its relationships with grain yield, radiation use efficiency (RUE), and N use efficiency for grain production (NUEg) in rice. Here, a two-year field experiment was conducted with two hybrid varieties under three N levels, 0 (N1), 90 (N2) and 180 kg ha−1 (N3), and two planting densities, 22.2 (D1) and 33.3 hills m−2 (D2). On average, a 3.4% higher yield and 4.4% higher NUEg were observed under N2D2 compared with N3D1. The extinction coefficient for N (KN) and light (KL) and their ratio (KN/KL) at the heading stage were significantly affected by the N rate, planting density, and their interaction. KN decreased with the increase of N input or planting density. Compared with N1, KN decreased by 43.5 and 58.8% under N2 and N3, respectively, and KN under D2 decreased by 16.0% compared with D1. Higher KL and KN/KL values were observed under a low N rate, while the opposite trend was shown under a high N rate. Moreover, increasing planting density resulted in a decrease in KL and KN/KL values. Compared with N3D1, N2D2 had higher KL and KN, and thus comparable KN/KL. Correlation analysis further revealed that KL was negatively correlated with RUE, while KN and KN/KL were positively correlated with NUEg. Therefore, increasing planting density under reduced N input could ensure rice yield while improving resource use efficiency via regulating canopy light and N distribution.

Lespedeza potaninii Vass seed yield response to plant density and phosphate fertilization in Northwest China

Lespedeza potaninii Vass is a highly drought-resistant China native legume plant, which plays an important role in animal husbandry and ecological restoration. However, there are few reports on the agricultural practices of its seed production. We evaluated the effect of four plant densities (33,333, 44,444, 66,666, and 133,333 plants ha−1) and five phosphate fertilizer rates (0, 45, 90, 135, and 180 kg ha−1) on seed yield, seed yield components and agronomic traits from the year 2020–2022. Correlation and structural equation model (SEM) analyses were used to determine the contribution of yield components to seed yield per plant. Year, plant density, phosphorus fertilizer rate and their interaction (P<0.05) significantly influenced the seed yield of L. potaninii Vass. The maximum average seed yield over 3 years (570 kg ha−1) occurred at the plant density of 44,444 plants ha−1 and phosphate fertilizer rate of 90 kg/ha. All the yield components, except 1000-seed weight, were significantly correlated with seed yield per plant. The racemes per stem, florets per raceme and pods per raceme had significant positive correlation, and stems per square meter and biomass had significant negative correlation with seed yield per plant. Increasing phosphorus fertilizer increased seed yield per plant. However, increasing plant density decreased seed yield per plant. Our findings enable further understanding of the mechanism of seed yield response to plant density and phosphorus fertilization in L. potaninii Vass and provide a reference for appropriate agronomic measures to improve seed yield of L. potaninii Vass and similar shrubs.

The development of pleiotropic phenotypes in powdery mildew-resistant barley and Arabidopsis thaliana mlo mutants is linked to nitrogen availability.

Powdery mildew-resistant barley (Hordeum vulgare) and Arabidopsis thaliana mlo mutant plants exhibit pleiotropic phenotypes such as the spontaneous formation of callose-rich cell wall appositions and early leaf chlorosis and necrosis, indicative of premature leaf senescence. The exogenous factors governing the occurrence of these undesired side effects remain poorly understood. Here, we characterised the formation of these symptoms in detail. Ultrastructural analysis revealed that the callose-rich cell wall depositions spontaneously formed in A. thaliana mlo mutants are indistinguishable from those induced by the bacterial pattern epitope, flagellin 22 (flg22). We further found that increased plant densities during culturing enhance the extent of the leaf senescence syndrome in A. thaliana mlo mutants. Application of a liquid fertiliser rescued the occurrence of leaf chlorosis and necrosis in both A. thaliana and barley mlo mutant plants. Controlled fertilisation experiments uncovered nitrogen as the macronutrient whose deficiency promotes the extent of pleiotropic phenotypes in A. thaliana mlo mutants. Light intensity and temperature had a modulatory impact on the incidence of leaf necrosis in the case of barley mlo mutant plants. Collectively, our data indicate that the development of pleiotropic phenotypes associated with mlo mutants is governed by various exogenous factors.

Transcriptome Analysis of Intermittent Light Induced Early Bolting in Flowering Chinese Cabbage.

In flowering Chinese cabbage, early booting is one of the most important characteristics that is linked with quality and production. Through fixed light intensity (280 μmol·m-2·s-1) and fixed intermittent lighting in flowering Chinese cabbage, there was early bolting, bud emergence, and flowering. Moreover, the aboveground fresh weight, blade area, dry weight of blade, and quantification of the leaves in flowering Chinese cabbage were significantly reduced, while the thickness of tillers, tillers height, dry weight of tillers, and tillers weight were significantly increased. The chlorophyll contents and soil-plant analysis and development (SPAD) value decreased in the early stage and increased in the later stage. The nitrate content decreased, while the photosynthetic rate, vitamin C content, soluble sugar content, soluble protein content, phenolic content, and flavonoid content increased, and mineral elements also accumulated. In order to explore the mechanism of intermittent light promoting the early bolting and flowering of '49d' flowering Chinese cabbage, this study analyzed the transcriptional regulation from a global perspective using RNA sequencing. A total of 17,086 differentially expressed genes (DEGs) were obtained and 396 DEGs were selected that were closely related to early bolting. These DEGs were mainly involved in pollen wall assembly and plant circadian rhythm pathways, light action (34 DEGs), hormone biosynthesis and regulation (26 DEGs), development (21 DEGs), and carbohydrate synthesis and transport (6 DEGs). Three hub genes with the highest connectivity were identified through weighted gene co-expression network analysis (WGCNA): BrRVE, BrLHY, and BrRVE1. It is speculated that they may be involved in the intermittent light regulation of early bolting in flowering Chinese cabbage. In conclusion, intermittent light can be used as a useful tool to regulate plant growth structure, increase planting density, enhance photosynthesis, increase mineral accumulation, accelerate growth, and shorten the breeding cycle.

Root-shoot ratio and its relationships with physiological characteristics, growth and biomass yield of Gynura procumbens under different shade levels and plant density

Gynura procumbens is one of the most common medicinal plants in the Asteraceae family, with extensive pharmacological properties. The experiment was conducted to evaluate the effects of different shade levels (0 and 30% shade) and plant density (9, 15, and 25 plants m-2) on root-shoot ratio and it is a relationship with physiology, growth, and biomass yield using split-plot design with three replications. Increasing shade level to 30% shade significantly decreased root-shoot ratio (RSR) by22.54%, while total leaf dry weight per plant (TLDW) and total leaf dry weight per square meter (TLDW m-2) increased by 35.64, 11.58, and 32.18%, respectively due to negative correlation with RSR. Increasing plant density from 9 to 25 plants m-2 significantly increased RSR and TLDW m-2 by 67.71 and 18.54%, respectively, while TLDW decreased by 57.31%. There was a negative correlation between RSR and biomass yield per plant. Under stressed conditions (full sunlight and high plant density), G. procumbent plants appeared to change strategy to absorb limited resources, allocate more biomass to the root system, and reduce aboveground parts' size to survive, resulting in high RSR. Keywords: Gynura procumbens, shade, plant density, root-shoot ratio, physiology, growth, biomass

Do newer maize hybrids grow roots faster and deeper?

AbstractUnderstanding historical changes in root depth attributes is needed for crop productivity and sustainability assessments, but such information is rare. We explored whether newer maize (Zea mays L.) hybrids grow roots faster and deeper than older hybrids and quantified the role of management and environment on root trait expression. We measured root front velocity (RFV) and maximum root depth in 11 Bayer Crop Science legacy hybrids released from 1983 to 2017 across five environments in the US Corn Belt during 2021 and 2022. Root depth was measured weekly during vegetative stages with manual probes and the maximum root depth at crop harvest with a Giddings probe. Results indicated that the RFV and maximum root depth slightly increased with the year of hybrid release (0.13% per year, p = 0.1) at 8.7 plants m−2. Historical increases in plant density from 4.7 to 8.7 plants m−2 lowered RFV and maximum root depth, but the new hybrids compensated for this loss, resulting in 4% higher RFV and 3% higher maximum depth when comparing systems from 1983 to 2017. The environment strongly influenced root trait expression (&gt;41%). Rain anomaly and soil bulk density explained a portion of this variation. We found a linear relationship between root depth and leaf number (R2 = 0.95) and a nonlinear relationship between RFV and maximum root depth (R2 = 0.77), which can stimulate crop model improvements. Faster and deeper roots were not correlated with maize yields in our environments. This study enhances our understanding of maize breeding impacts on root traits.

DENSIDADE DE SEMENTES E APLICAÇÃO FOLIAR DE FERTILIZANTE ORGANOMINERAL À BASE DE CÁLCIO E POTÁSSIO NA CULTURA DA AVEIA

Purpose: To present the benefits of increasing oat sowing density on productivity, uniformity, soil quality and reduction of pesticides and the use of an organomineral product based on calcium and potassium as an alternative to lodging control, promoting more sustainable cultivation systems. Theoretical framework: Increasing plant density can promote productivity, rapid soil coverage, reduction of weeds and greater harvest uniformity, reducing the use of pesticides. However, increasing seeding density can promote lodging. Lodging is the phenomenon in which plants leave the vertical position and fall to the ground, affecting the quality of the grains. The commercial product registered to control lodging is highly toxic to the environment. Organomineral sources with potassium and calcium represent an alternative for controlling lodging with reduced environmental impacts. Results: Benefits of increased seeding density to promote grain yield have been found for several crop species, reinforcing the need for adapting seeding density for oat crops. The use trinexapac-ethyl as a growth regulator, it poses risks of phytotoxicity and environmental contamination. In this context, several studies have indicated that potassium and calcium favor cell wall rigidity, potentially contributing to oat stem strength. Originality/value: This study provides significant contribution to the advancement of research on oat in Brazil, bringing new information benefiting farmers, technical assistance agents, and the food industry and improving the production system to ensure food security and care for the environment.

Increasing Planting Density and Optimizing Irrigation to Improve Maize Yield and Water-Use Efficiency in Northeast China

We investigated the effects of variety, planting density, and irrigation amount on grain yield, water-use efficiency (WUE), and evapotranspiration (ETc). The trial was conducted in Tong Liao, Inner Mongolia, from 2021 to 2022, with compact variety Dika159 (DK159) and conventional variety Zhengdan958 (ZD958) as the test materials. The planting density was set to 6.0 × 104 plants/ha (D1, local farmer planting density) and 9.0 × 104 plants/ha (D2), with five irrigation levels: 450 mm (W450, irrigation amount used by local farmers, CK); 360 mm (W360); 270 mm (W270); 180 mm (W180); and 90 mm (W90). The results indicate that the yield and WUE of variety DK159 increased by 7.48% and 5.00%, compared to ZD958, respectively. Increasing planting density enhanced yield by 13.32–15.57% in maize yield and 9.55–11.47% in WUE. Maize yield exhibited a trend of increasing linearly with the irrigation amount before reaching a plateau, reaching a maximum (16.62–17.39 t/ha) and high WUE (2.45–2.49 kg/m3) with DK159-D2-W270. The highest water consumption intensity occurred during the silking stage to the milk stage for different densities and varieties. The results indicate that selecting compact varieties, increasing planting density, and optimizing irrigation amount through integrated drip irrigation and water fertilizer can effectively improve maize yield and WUE.

Increasing planting density increases fruit mass and reduces the dispersal ability of a range‐expanding invasive plant, Mikania micrantha

AbstractAimInvasive plants may evolve a suite of distinctive traits during spread in the new range. Among these traits, dispersal ability is an important trait determining the invasion speed of exotic plants. There is evidence that higher dispersal ability is favoured at the invasion front, where population density may be low. However, no study has explicitly tested how planting density in a common garden affects the dispersal ability of invasive plants.LocationHainan island of China.MethodsIn this study, using 27 populations of an invasive plant, Mikania micrantha, which is expanding its range on Hainan island of China, we examine how three dispersal‐related traits (i.e. dispersal ability, fruit mass, and pappus radius) change with distance from invasion centre and field population density, and how planting density in a common garden affects dispersal traits.ResultsDispersal traits did not change with distance from the invasion centre and field population cover either in the natural environment or in the common garden. In the common garden, increasing planting density from one to five plants per pot increased fruit mass and decreased dispersal ability, indicating that the effect of density on dispersal traits could not be detected in the field. The relationship between dispersal ability in the natural environment and that in the common garden was positive but significant only under the five plants per pot treatment, possibly because dispersal traits in natural conditions were selected under high‐density growth conditions.Main ConclusionsOur results indicate that increasing population density may increase fruit mass and reduce the dispersal ability of range‐expanding invasive plants. We suggest that further studies exploring the patterns of dispersal traits in range‐expanding invasive plants in a common garden should consider intraspecific competition.

From a point to a range of optimum estimates for maize plant density and nitrogen rate recommendations

AbstractThe interaction between nitrogen (N) rate, plant density, and hybrid on net return to seed and fertilizer cost remains unknown but important to be addressed given the multi‐input decision process corn growers make every year. We collected grain yield from a factorial experiment with five N rates (0–291 kg N ha−1), five plant densities (3.7–11.4 plants m−2), and four hybrids (old vs. new) over 2 years in Iowa. Data were sufficiently modeled with a quadratic plateau model with continuous covariate terms to include N × plant density interactions (R2 = 0.925, n = 387). We found a wide range of plant densities (6.7–8.4 plants m−2) and N rate (150–212 kg N ha−1) combinations to achieve 99% of the maximum net revenue. The economic optimum N rate increased with increasing plant density from 4 to 7 plants m−2. The fundamental relationships between grain yield response to N fertilizer and plant density were similar across old and new hybrids; however, the absolute values were different, with newer hybrids having 20% higher economic optimum N rate and 23% higher yield than the older hybrids. We concluded that by accounting for two inputs into the revenue equation, a larger range of combinations was found to achieve 99% of the maximum net revenue. Our study offers new insights into N rate by plant density by hybrid interaction to assist future research.

Bioelectricity generation in plant microbial fuel cells: Influence of vegetation density and unsaturated soil properties

Plant microbial fuel cells (PMFCs) have promising potential in various geoenvironmental engineering applications such as green roofs, biosensors, water purification and soil remediation. However, the vulnerability of PMFCs to drought stress and the unknown interplay between bioelectricity, planting density, and unsaturated soil properties pose significant challenges for their applications. The research objective is to investigate the effects of planting density on bioelectricity generation under drought conditions. The research was conducted using vegetation Hydrocotyle vulgaris at four different planting densities in silty soil. Bioelectricity and unsaturated soil properties, including water content and suction, were monitored. The results indicated that moderate increase in planting density could enhance the power density of PMFCs up to 4.5 times. This is because of the increased availability of root exudates for microbial activity with increasing root biomass and decreased internal resistance by extending the soil pore space. It was also found that plant roots could affect bioelectricity generation by altering unsaturated soil properties, such as the air-entry value of soils and soil pore structure. However, high planting densities reduced bioelectricity due to increased internal resistance from roots occupancy and evapotranspiration-induced crack initiation. This research provides valuable insight into optimizing PMFC performance and sustainability.

Formation of yield and quality of topinambur tubers with different planting techniques

To expand the production of topimanbur in the Russian Federation, it is necessary to develop adaptive cultivation technologies in various regions of the country. Field research was carried out on the territory of the educational and scientific experimental field of the Perm State Technical University. Three variants of the planting scheme were studied: 70x30, 70x40 and 70x50 cm and three variants of the weight of the planting tuber: 20-40 g, 41-60 g and 61-80 g. The applied agrotechnical measures are generally accepted for the non–Chernozem zone. The technology of planting topinambur is a comb. The research results show that with planting schemes of 70x30, 70x40 and 70x50 cm, topinambur forms the exact yield of tubers – 18.3-19.3 t/ha. When used for planting tubers weighing 41-80 g, the yield increases by 1.1-1.7 t/ha, compared with the planting fraction of 21-40 g, due to an increase in plant density by 0.1 pcs. /m2. Biological yield indicators fully reflect the actual yield. Under the studied planting schemes, it was also the same and amounted to 2002.6-2177.9 g/m2, and when planted with larger tubers, it was 271.7-277.0 g/m2 higher than tubers of 20-40 g. The proportion of tubers of the small fraction – 48-59 % prevails in the Jerusalem artichoke crop. The share of the food fraction is 8-16 %. The fractional composition of tubers in the crop does not depend on the mass of the planting tuber. The share of planting tubers in the harvest with schemes 70x30 and 70x40 cm is higher by 6-8 %. A higher dry matter content in tubers was observed when planting tubers weighing 20-60 g – 21.3-21.6 %, and vitamin C – when planting tubers 61-80 g – 14.5 mg/kg. The planting scheme does not affect the biochemical composition of topinambur tubers.

Timing of connection to mycorrhizal networks matters: Nutrition, N fixation, and transfer of fixed N in maize-bean intercropping

The mycorrhiza-mediated transfer of nutrients to plants connected through mycorrhizal networks may be managed through the timing at which plants integrate to the networks and the integrity of those networks. This is particularly relevant for intercropping agrosystems. We used soil tillage to disrupt mycorrhizal networks and sowing time treatments to manipulate the connection time of maize and bean in a field experiment. We hypothesized that 1) the benefits from connecting to mycorrhizal networks would be greater for the crop that is established first and retrieved resources from the network without competition, and 2) tillage disruption delaying colonization and connection to preserved mycorrhizal networks would reduce mycorrhizal colonization in roots and soil, crop nutrition, N fixation by beans, and transfer of fixed N to maize. Mycorrhizal network disruption with tillage reduced early mycorrhizal development in roots and soil, and N and P nutrition of both crops. In general, sowing time had no effect in maize but tillage increased plant density, growth, and the yield of maize by alleviating soil compaction. Reduced tillage and early sowing increased nutrition, development, N fixation and yield of bean. N derived from symbiotic fixation in bean and transferred to maize were higher with bean sown before maize under reduced tillage. Early connection to mycorrhizal networks favored mostly bean and made little difference to maize regardless of sowing time, contrary to our expectations. The greatest overall benefit for both crops was obtained when bean was sown before maize and connected early to preserved mycorrhizal networks under reduced tillage.

Plant Spacing and Nitrogen Fertilizer Effect on Potato (Solanum Tuberosum) Growth, Yield and Quality: Review

Potato is regarded as ahigh-potential food-security crop because of its ability to provide a high yield of high-quality product per unit input with a shorter crop cycle (mostly &lt; 120 days) than major cereal crops. Potato demands high level of soil nutrients due to relative poorly developed and shallow root system in relation to yield. Factors that limit crop yield (both in quantity and quality) can be categorized into four major headings such as soil, genetic, climatic and management practices. Intra-row spacing had great influence on economically important characteristics such as total yield, processing grade yield, tuber size distribution and tuber quality. As plant density increases, there is a marked decrease in plant size and yield plant-1. This effect is due to increased inter-plant competition for water, light and nutrients. Proper N fertilization is critical for optimizing potato yield and quality. application of N exerted significant influence on all the growth parameters that is showing positive increment. Nitrogen supply plays a paramount part in the balance between vegetative and its reproductive for potato. nitrogen fertilization influences the potato tuber yield and quality. Low nitrogen usually causes low dry matter and sugar levels, while excessive nitrogen promotes vine growth and delays tuber initiation. Nitrogen management is critical for building leaf area to harvest sunlight for photosynthesis to maximize yield. Therefore, effective management of nutrients and proper use of plant spacing is critical for potato production, as tuber yield and quality.

ВЛИЯНИЕ РОНКОЛЕЙКИНА НА МОРФОМЕТРИЧЕСКИЕ И ГЕМАТОЛОГИЧЕСКИЕ ПОКАЗАТЕЛИ И ФАГОЦИТАРНУЮ И ГЕМАТОЛОГИЧЕСКИЕ ПОКАЗАТЕЛИ И ФАГОЦИТАРНУЮ

Cultivated hydrobionts under intensive aquaculture conditions are exposed to stress factors associated with artificial habitats, increased planting density, periodic fishing, etc. At the same time, they experience a decrease in resistance and resilience and an increase in morbidity. A good solution to this problem is the use of immunomodulators. This article presents the results of a study of the effect on fish of the immunomodulator Roncoleukin, which is a dosage form of recombinant human interleukin-2 (IL-2) isolated and purified from yeast cells (Saccharomyces cerevisiae). The subject of the study was the three-year-old Arctic char (Salvelinus alpinus). The evaluation was based on morphometric, hematological (erythro- and leukogram) and cytochemical (lysosomal cation test) indicators. The coefficient of variation of the size and weight parameters of the treated fish was low compared to the con- trol group. This indicates uniform growth of fish fed Roncoleukin, which is a great advantage in fish farming and provides more efficient use of feed. Blood for analysis was taken from the tail vein of the fish in vivo. The results showed a positive effect of the drug on the activation of erythropoiesis and leukopoiesis. There was a significant increase in the proportion of mature segmented neutrophils (the main blood microphages belonging to the non-specific link of cellular immunity) in the leukocyte formula due to a decrease in lymphocytes (specific immunity). An increase in the content of nonenzymatic lysosomal cationic proteins (defensins) in blood neutrophils can indicate a high level of cellular protection of microphages (neutrophils). The results of the study showed a positive effect of the drug Roncoleukin, which can be recommended for use in the ferming of Arctic char.

Effect of Change of Agronomic Practices on Nutritive Value of Hybrid Fodder Sorghum Cultivated in Lowland Paddy Fields of the Dry Zone of Sri Lanka

This study was conducted to investigate the effect of low fertilizer rate and irrigation along with increased plant density on nutritive value of hybrid fodder sorghum cultivated in lowland fallowed paddy fields in dry zone during May to September. Seeds were sown in Yala season and continued as a ratoon crop to inter-monsoonal (Third) season. Four agronomic management packages (AMP1, AMP2, AMP3 and AMP4), which differ in fertilizer application rates, plant spacing, and irrigation intervals were tested with two fodder sorghum varieties (SX-17 and Dairygreen) in a split-plot design. The initial and first ratoon crops were harvested at dough grain stage. High fertilizer rate in combination with short irrigation interval, resulted in high (P&lt;0.05) crude protein content in the initial harvest. AMP2 and AMP4 produced equally high (P&lt;0.05) total dry matter yield (DMY) for SX-17 (24.7 and 20.9 MT/ha, respectively) and Dairygreen (27.7 and 25.7 MT/ha, respectively) varieties. Total digestible organic matter, crude protein and metabolizable energy yields were higher under AMP2 and AMP4 compared to other two packages for both varieties. Nutritive value was high in SX-17 under AMP1 for ratoon crop. In conclusion, AMP4 with plant spacing of 45 x 15 cm, low fertilizer rate (338-47-28 kg/ha, urea-TSP-MOP) and extended irrigation interval, could be recommended for cultivation of hybrid fodder sorghum in lowland paddy fields in the dry zone during Yala season. However, for cultivating SX-17 targeting to produce fodder with high nutritive level, AMP1 with spacing of 45 x 30 cm, high fertilizer rate (400-62-37 kg/ha of urea-TSP-MOP) and frequent irrigation could be recommended.