Low Plant Density Research Articles

Planting density effect on poplar growth traits and soil nutrient availability, and response of microbial community, assembly and function

BackgroundThe interaction between soil characteristics and microbial communities is crucial for poplar growth under different planting densities. Yet, little is understood about their relationships and how they respond to primary environmental drivers across varying planting densities.ResultsIn this study, we investigated poplar growth metrics, soil characteristics, and community assembly of soil bacterial and fungal communities in four poplar genotypes (M1316, BT17, S86, and B331) planted at low, medium, and high densities. Our findings reveal that planting density significantly influenced poplar growth, soil nutrients, and microbial communities (P < 0.05). Lower and medium planting densities supported superior poplar growth, higher soil nutrient levels, increased microbial diversity, and more stable microbial co-occurrence networks. The assembly of bacterial communities in plantation soils was predominantly deterministic (βNTI < -2), while fungal communities showed more stochastic assembly patterns (-2 < βNTI < 2). Soil available phosphorus (AP) and potassium (AK) emerged as pivotal factors shaping microbial communities and influencing bacterial and fungal community assembly. Elevated AP levels promoted the recruitment of beneficial bacteria such as Bacillus and Streptomyces, known for their phosphate-solubilizing abilities. This facilitated positive feedback regulation of soil AP, forming beneficial loops in soils with lower and medium planting densities.ConclusionsOur study underscores the critical role of planting density in shaping soil microbial communities and their interaction with poplar growth. This research carries significant implications for enhancing forest management practices by integrating microbiological factors to bolster forest resilience and productivity.

Mechanized Transplanting Improves Yield and Reduces Pyricularia oryzae Incidence of Paddies in Calasparra Rice of Origin in Spain

The rice variety Bomba is grown in Calasparra—a rice of origin in southeast Spain—resulting in a product with excellent cooking quality, although its profitability has declined in recent years due to low grain yields and susceptibility to rice blast disease (Pyricularia oryzae Cavara). An innovation project to test the efficacy of mechanized transplanting against traditional direct seed sowing was conducted in 2022 and 2023 at four locations for the first time. A lower plant density (67–82 plants m−2) and shorter plants with higher leaf nitrogen content were observed in transplanted plots compared with seed sowing (130–137 plants m−2) in the first year. The optimal climatic conditions for P. oryzae symptom appearance were determined as temperatures of 25–29 °C and a 50–77% relative humidity. The most-affected sowing plots presented 3–20% leaf area damage and a reduction in yield to values of 1.5 t ha−1 in the first year and 2.12 t ha−1 in the second year. In transplanted plots, there was generally less humidity at the plant level and therefore, disease incidence was low in both seasons. Grain yields did not significantly differ among the treatments studied; however, there were differences in the yield components of panicle density and the number of grains for panicles. Principal component analysis revealed two principal components that explained 81% of the variability. Variables related to yield contributed positively to the first component, while plant biomass variables contributed to the second component. Plant density, tiller density, and panicle density were found to be positively correlated (r &gt; 0.81 ***). Overall, transplanting (frame of 30 × 15–18 cm2) resulted in uniform crop growth with less rice blast disease, as well as higher grain yields (2.92–3.89 t ha−1), in comparison with the average for the whole D.O. Calasparra (2.3–2.5 t ha−1) in both seasons and a good percentage of whole grains at milling. This is novel knowledge which can be considered useful for farmers operating in the region.

Planting Density and Sowing Date Strongly Influence Canopy Characteristics and Seed Yield of Soybean in Southern Xinjiang

Southern Xinjiang is an important soybean production region in China. However, the short growing season and the cultivation of winter crops (such as wheat) in the region limit the expansion of soybean planting areas. An increased planting density can compensate for the loss in yield due to delayed sowing. To identify the quantitative relationship between increased density and delayed days, a two-year field experiment was conducted at the Tarim University Agronomy Experiment Station. Two sowing dates (April 7 (S1) and May 7 (S2)) and three planting densities of 206,800 plants·ha−1 (D1), 308,600 plants·ha−1 (D2), and 510,200 plants·ha−1 (D3) were used to compare various plant growth parameters and canopy characteristics. Late sowing and a high planting density significantly increased the plant height (S2 was 37.3% higher than S1, and D3 was 17.6% and 8.8% higher than D1 and D2), main stem internode, petiole length, and the mean tilt angle of the leaves (S2 was 22.5% higher than S1, and D3 was 11.7% higher than D2) but reduced the stem diameter (D3 was 28.6% and 12.5% lower than D1 and D2), branch number (S2 was 26.7% lower than S1, and D2 was 75% lower than D1), canopy light transmittance (S2 was 49.2% lower than S1, and D3 was 36.7% and 20.8% lower than D1 and D2), photosynthetic rate, and dry matter. The highest yield was achieved at S1D1, but the lowest yield was found for S2D1. Overall, the results suggest that earlier sowing and a lower planting density contribute to achieving an optimum canopy structure and higher yield. Our conclusions provide a reference for soybean production in southern Xinjiang.

Effect of Tree Density on Yield and Fruit Quality of the Grafted Hazelnut Cultivar 'Tonda Francescana®'.

Optimizing planting density is crucial for balancing resource competition, light penetration, and tree productivity in orchard systems. This study investigateed the impact of planting density on the yield and fruit quality of the hazelnut cultivar 'Tonda Francescana®' grafted onto Corylus colurna L. rootstocks. The research aimed to assess how different planting densities influenced light penetration, canopy volume, yield, and the nutritional profile of hazelnuts during their sixth growing season. Three planting densities were tested: 625, 1250, and 2500 trees per hectare (low, medium, and high density, respectively). The results show that medium-density planting provided the best balance between light availability, canopy development, and yield efficiency. The synthesis of monounsaturated fatty acids (MUFA) and α-tocopherol (vitamin E) was more prominent in the medium-density system (80.2% and 10.3%, respectively), suggesting a favorable metabolic response to moderate competition for resources. In contrast, high-density planting yielded the most per hectare (2898 kg/ha) but exhibited lower individual tree productivity (1.16 kg). Low-density planting had the highest light penetration (53%) but lower overall yield (822 kg/ha) and quality, with greater starch accumulation in the fruit. In general, medium-density planting optimized both yield and kernel quality, with potential implications for orchard management and breeding strategies to enhance hazelnut production and nutritional value.

Enhancing the Performance of Unmanned Aerial Vehicle-Based Estimation of Rape Chlorophyll Content by Reducing the Impact of Crop Coverage

Estimating leaf chlorophyll content (LCC) in a timely manner and accurately is of great significance for the precision management of rape. The spectral index derived from UAV images has been adopted as a non-destructive and efficient way to map LCC. However, soil background impairs the performance of UAV-based LCC estimation, limiting the accuracy and applicability of the LCC estimation model, and this issue remains to be addressed. Thus, this research was conducted to study the influence of soil pixels in UAV RGB images on LCC estimation. UAV campaigns were conducted from overwintering to flowering stages to cover the process of soil background being gradually covered by rapeseed plants. Three planting densities of 11.25, 18.75, and 26.26 g/m2 were chosen to further enrich the different soil background percentage levels, namely, the rape fractional vegetation coverage (FVC) levels. The results showed that, compared to the insignificant difference observed for the ground measured LCC at a certain growth stage, a significant difference was found for most of the spectral indices extracted without soil background removal, indicating the influence of soil background. Removing soil background during the extraction of the spectral index enhanced the LCC estimation accuracy, with the coefficient of determination (R2) increasing from 0.58 to 0.68 and the root mean square error (RMSE) decreasing from 5.19 to 4.49. At the same time, the applicability of the LCC estimation model for different plant densities (FVC levels) was also enhanced. The lower the planting density, the greater the enhancement. R2 increased from 0.53 to 0.70, and the RMSE decreased from 5.30 to 4.81 under a low planting density of 11.25 g/m2. These findings indicate that soil background removal significantly enhances the performance of UAV-based rape LCC estimation, particularly under various FVC conditions.

The influence of planting density on the oil and fatty acids content of soybean in hydroponic and soil conditions of the Ararat Valley

Background: Plant seed oils are major renewable resources from nature that can be used in multiple applications. Oils and fats are a vital component of human diets. About 1/3 of the daily energy requirements of a healthy diet come from fats. Each branch of the food industry has its own demands for the fatty acid composition of seed oils. High amounts of polyunsaturated fatty acids are a requirement of healthy diets. However, food manufacturers need highly saturated fatty acids because they need oil that is resistant to high temperatures and oxidation. Soybean oil is second only behind palm oil as the most commercially abundant plant oil globally. Soybean has been recognized for its agricultural importance and their various positive effects on human health. Objective: to identify the quantitative changes of soybean fatty acids depending on the planting density and growing conditions in the Ararat Valley of Armenia. Methods: Soybean was grown in hydroponic and soil conditions of the Ararat Valley. The seeds were sown in the middle of April. Experiments were carried out in hydroponic equipment and soil with different planting densities (30, 50, 70 and 90 plants/m2). The oil content was measured by using the pulsed nuclear magnetic resonance method. The composition of fatty acids in seed oil was analyzed by chromatographic method on "Chromatec Crystal 5000" GC. Results: Oil content ranged from 19.6% to 24.4% in all variants. The maximum content was registered in soil with 30 plant/m2 planting density. Linoleic acid content ranged from 46.35 to 51.28% of the total fatty acid content, regardless of planting density and growing media. The content of linolenic acid ranged from 4.13 to 5.11% in all variants. The maximum content of ω-3 and the minimal content of ω-9 was recorded in hydroponics at 30 plants/m2 planting density. The highest percentage of stearic acid was observed in the soil variant with a planting density of 30 plants/m2. Interestingly, the variants did not differ in the total content of the 5 main fatty acids (98.84-98.95%). Growing medium had no significant effect on the total saturated fatty acids content; in all variants it ranged from 14.29% to 14.83%. Total unsaturated fatty acids content ranged from 85.2% to 85.7%. The hydroponic variant with a planting density of 30 plants/m2 had the lowest ratio of ω-6 and ω-3 fatty acids (10:1). Conclusion: Planting density and growing media had a significant influence on the content of monounsaturated and polyunsaturated fatty acids. Under hydroponic conditions the lowest content of monounsaturated and the highest content of polyunsaturated fatty acids were observed at the lowest planting density (30 plants/m2), which can be used as a functional food for daily consumption. Keywords: Glycine max (L.) Merr., soilless culture, ω-3, ω-6, ω-9, saturated acids.

Impact of planting density and shoot thinning on alstroemeria flowering, soil attributes and cost economics

A field experiment was conducted to assess the impact of various planting densities and levels of shoot thinning on cut flower yield, quality, soil chemical properties and cost economics in the commercially cultivated alstroemeria cultivar 'Capri'. The experiment involved three planting densities (4, 6 and 8 plants/m2) along with three shoot thinning levels (10 %, 20 % and 30 %). It was observed that higher planting density (4 plants/m2) promoted the length of cut stem, early bud formation, and flowering, optimal quality parameters, including maximum stem thickness, cut stem weight, floret quantity/stem, floret size, number of flowering stems/plant (yield) and vase life. Exclusive use of higher vegetative mass removal (30 % shoot thinning) was found to improve quality parameters such as the length of cut stem, number of flowering stems, stem thickness, weight of cut stem, floret quantity/stem, floret size, vase life, and early flowering. Soil samples were collected from each treatment and the consequent lab analysis revealed that the lower planting density and shoot thinning level resulted in maximum soil organic carbon, nitrogen, phosphorous and potassium content. In conclusion, planting density of 4 plants/m2 and 30 % shoot thinning emerged as the optimal combination for enhancing quantitative parameters in commercial alstroemeria cultivation. The study underscores the importance of strategic planting practices and vegetative mass management for maximizing yield and quality in alstroemeria production, along with ensuring higher economic returns.

Effects of planting date and density on cotton cultivars in sub‐Saharan Africa rainfed conditions: A case study in Mali

AbstractMali is among Africa's three biggest cotton (Gossypium hirsutum L.)‐producing countries, and cotton growing is the principal driving force behind Mali's agricultural sector. Cotton production is rainfed on small‐scale family farms as a commercial crop alongside staple crops grown for subsistence. Cultivar choice, planting date, and planting density are critical elements for seed cotton yield that should be optimized. This study aimed to understand the interactions between planting dates and planting densities for the optimal production of four cotton cultivars in Mali. Two trials were set up in two seasons at the Finkolo and N'Tarla research stations. A split‐plot design with four replications was used, with planting dates (early and delayed by 3 weeks) as the main plots and planting density (41,666; 83,333; and 166,666 plants/ha) and cultivar (Malian NTA MS334, Togolese STAM 129A, Australian SIOKRA L23, and Brazilian BRS 293) as the subplots. In 2021, seed cotton yield was 1263 kg/ha for early planting versus 361 kg/ha for late planting. Medium and high planting densities produced the same yield level, higher than the low planting density. Regardless of the planting density, early plantings' average capsular weight and seed index were higher than those of late plantings. The African cultivars (STAM 129A and Malian cultivar NTA MS334) were the most productive. Due to significant interactions on fiber percentage and to optimize cotton yields in Mali, planting should be early, with planting densities higher than 41,666 plants/ha, and either of the African cultivars tested should be used.

Rainforest Alliance-UTZ cocoa certification scheme adoption: Determinants and financial implications for cocoa production in the Centre region of Cameroon

This study evaluates the level of adoption of the Rainforest Alliance-UTZ cocoa certification scheme in the Centre region of Cameroon, ascertains the drivers of adoption, and evaluates the financial implications of the levels of adoption. Using cross-sectional data obtained from 100 cocoa growers in the Central region of Cameroon and employing a Generalised Ordered Logit estimation technique alongside a one-way ANOVA test and Tukey’s test for post-hoc estimations, we show that 50%, 17%, and 33% of cocoa growers are complete adopters, partial adopters, and non-adopters of the Rainforest Alliance-UTZ cocoa certification scheme, respectively. The findings also reveal that the likelihood of having partial or complete adoption is higher among farmers who have introduced orange trees in their orchards, own more extensive orchards, and have more years of experience in cocoa farming. Furthermore, the likelihood of having complete adoption is higher for farmers with a lower planting density in their orchards and a tertiary level of schooling. Farmer’s age has a mitigated effect on the likelihood of adopting certification schemes by reducing the likelihood of having partial or complete adoption against non-adoption and at the same time raising the likelihood of complete adoption against no or partial adoption. The study also concludes that the financial performance of cocoa growers varies based on their level of adoption of the Rainforest Alliance-UTZ certification scheme. Farmers who have achieved certification status tend to have higher farm earnings. Based on these findings, non-adopters and partial adopters are encouraged to fully adhere to the Rainforest Alliance-UTZ certification standards. By doing so, they can increase their financial gains, enhance their livelihoods, and reduce the negative environmental impacts of cocoa farming.

APW: An ensemble model for efficient wheat spike counting in unmanned aerial vehicle images

The accurate estimation of wheat ear is of great significance to gain high yield for ensuring food security. The use of computer vision for wheat ear counting to improve the estimation efficiency and accuracy has been explored by many scholars. However, existing single-computer vision recognition methods have insufficient robustness and recognition of adherent wheat ears. This study mainly focused on to solve the problem of adherent wheat ears, and proposed a combined algorithm called “APW” that ensemble with alternating direction methods of multipliers (ADMM), Potts algorithm and Watershed to achieve fast recognition and counting of wheat ears. The images of wheat ears were collected under three different scenarios including growth stages, planting densities, and flight heights by using unmanned aerial vehicle (UAV), and the Potts model was used to recognise the images. The masked images of the wheat ear were converted into a greyscale image, and were layered using a greyscale gradient. Finally, the watershed algorithm was used to segment adherent wheat ears in the layered image, and the centroids were labelled and counted. The results shows that the best accuracy was obtained under low planting density scenario, with an R2 of 0.89 and a root mean square error (RMSE) of 3.72, suggesting that APW can handle scenarios with large background differences and low target adherence. These findings provides a new approach for efficient counting of wheat ears in UAV acquired images.

Soil respiration response to reductions in maize plant density and increased row spacing (Southeast pampas, Argentina)

Previous studies have recognized the influence of crop cover and agricultural management on variables (soil temperature, soil moisture, and root biomass) that influence soil respiration. However, despite the influence of plant density and row spacing on these variables in the maize crop (Zea mays L.), their impact on soil respiration has received little attention. Thus, the aims of this study were (i) to investigate whether reducing plant density and row spacing influences soil respiration, and (ii) to identify the controlling variables (soil temperature and soil moisture) underlying this response. We conducted field experiments in Balcarce, Argentina, over two seasons. Treatments included (i) maize crops at high plant density (≈8 plants m−2) and narrow rows (0.52 cm, HDN), and (ii) maize crops at low plant density (≈6.5 plants m−2) and wide row spacing (0.70 cm; LDW). Leaf area index (LAI), soil CO2 fluxes, soil superficial temperature, and moisture (characterized by the water-filled pore space, WFPS) were assessed throughout the growing season. Grain yield and cumulative soil CO2 emissions were determined at the final harvest. Major findings relevant to understanding the influence of reducing plant density and wider row spacing on instant CO2 fluxes include: (i) LAI reductions were related to higher superficial soil moisture, which was consistent at LAI ≥ 3; suggesting higher decreases in water uptake than increases in soil evaporation, and in turn (ii) increments in soil moisture were associated with higher CO2 fluxes. While lower plant density and wider row spacing had notable short-term effects on WFPS and soil respiration fluxes, they did not significantly affect cumulative soil respiration throughout the growing season. However, the combination of this practice with low-yield potential genotypes that exhibit low stability to changes in resource availability can increase CO2 emissions per unit of grain yield. These findings contribute to a better understanding of the impacts of management practices on soil respiration and, consequently, on carbon cycling within agricultural ecosystems.

The genotypic variation in the positive response of sorghum to higher sowing density is linked to an increase in water use efficiency

In semi-arid tropical areas, sorghum is sown at very low planting densities. Hence, increasing plant density represents an opportunity to improve productivity. However, assessing the expected increase in water needs is critical prior to testing higher densities under rainfed conditions. This was tested with a panel of elite cultivars in field and lysimiter experiments, and testing the effects of two density treatment, high (HD, 22 plants.m-²) and low (LD, 11 plants.m-²), on grain and biomass yield and on water use and water use efficiency (WUE). Doubling the conventional sowing density significantly increased biomass and grain yield, with a genotypic variability in the biomass response. No link was found between the response to density and the maintenance of the tillering capacity, whereas the response to density was somewhat explained by a differential increase in the leaf area index under high density (r=0.43 P<0.05). Lysimeter experiments showed that, compared with the conventional density, the high-density treatment had 62% increase in biomass vs a 38% increase in water use, resulting in a 17% higher WUE on average of the genotypes tested. There was an appreciable genotypic variability in this degree of WUE increase under high density. The most striking result was the very tight positive link between the biomass response to density and the differential increase in WUE in the dry season (r=0.91 P<0.0001), whereas in the wet season this link was negative (r=-0.48 P<0.02). This work shows that intensifying sorghum production by increasing sowing density is possible, in the short term using cultivars that show the largest WUE increase under high density, in the longer term by breeding high-density adapted cultivars, targeting plant traits that explain the tight link between higher WUE and higher yield under high density.

Increasing the planting density of Cryptolepis sanguinolenta (Lindl.) Schlt increased root biomass and cryptolepine yield

Cryptolepis sanguinolenta (Lindl.) Schlt. is an important multipurpose medicinal plant used for the treatment of ailments such as malaria. Despite the ongoing efforts in domesticating the herb, the ideal planting density and its benefits are unknown. A study was conducted to determine the influence of six C. sanguinolenta accessions and three planting densities (15, 30 and 45 plants/1.8 m2) on root biomass, cryptolepine concentration and cryptolepine yield. Also, benefit-cost ratios were determined for each plant density across the four cultivation periods (9, 12, 15 and 18 months). The cultivation of C. sanguinolenta at the highest planting density (45 plants/1.8 m2) increased root biomass (value), cryptolepine content (2.08 mg/100 mg dry root) and cryptolepine yield (23.31 mg mg/1.8 m2) compared to those cultivated at lower planting densities (15 and 30 plants/1.8 m2). The duration for growing C. sanguinolenta had a more significant influence on cryptolepine yield but not the cryptolepine content. Plants cultivated for 15 months gave the maximum cryptolepine yield (10.33 g/bed), indicating 15 months as the optimum time to harvest the roots. The benefit-cost analysis revealed that growing the plant at a density of 45 plants/1.8 m2 (25,920 plants/acre) for 18 months was a more profitable venture with a benefit-cost ratio of 3.45. Commercial cultivation of C. sanguinolenta at 45 plants per bed area of 1.8 m2 (25,920 plants/acre) for 15–18 months is recommended as the most profitable and promising cropping practice to ensure the sustainable supply of planting material.

Alternative Agronomic Management Practices Through Fertilizer, Irrigation, and Plant Density Adjustments for Hybrid Fodder Sorghum (&lt;em&gt;Sorghum bicolor&lt;/em&gt; L. Moench)

Purpose: The basal fertilizer recommendation for growing hybrid fodder sorghum varieties in uplands involves relatively high quantities of Urea, TSP, and MOP, with rates of 100:90:65 kg/ha for SX-17 and 150:62:37 kg/ha for Dairy green. For both initial and ratoon crops, it is recommended to apply 150 kg/ha of urea as a top dressing. This study investigated the impact of reducing the fertilizer application rate to 75% and employing alternative agronomic practices on hybrid fodder sorghum varieties grown in lowland fallow paddy fields in the dry zone during the Yala and third seasons.Research Method: The agronomic management practices, including four basal fertilizer rates (Urea:TSP: MOP) of 100:90:65 (BD1), 150:62:37 (BD2), 75:68:49 (BD3), and 113:47:28 (BD4); two top-dressing urea fertilizer rates of 150 (TD1) and 112.5 kg/ha (TD2); two plant spacing configurations of 45x30 (WS) and 45x15 cm (NS); and two irrigation interval regimes, 5 days up to 30 days followed by 8 days (SI) and 7 days up to 30 days followed by 10 days (LI) were investigated. These factors were combined into four agronomic management packages: AMP1 (BD1, TD1, WS, SI), AMP2 (BD2, TD1, NS, SI), AMP3 (BD3, TD2, WS, LI), and AMP4 (BD4, TD2, NS, LI). The study used a split-plot design with three replicates and assessed various parameters, including plant height, stem diameter, plant weight, leaf area index (LAI), number of tillers, and fodder yield in both the initial fodder sorghum crop and the first ratoon crop. The crops were harvested when 50% of the panicles on the plants were at the milk and dough grain stages.Findings: The initial crop exhibited significantly heavier plants having wider stems when grown with higher fertilizer rates, wider plant spacing, and shorter irrigation intervals in AMP1. Irrespective of fertilizer rate and irrigation interval, the initial crops tended to have higher LAI with narrow plant spacing in AMP2 and AMP4. In the ratoon crops, wider plant spacing in AMP1 and AMP3 resulted in clumps with a greater number of tillers and heavier plants. However, the ratoon crops also exhibited higher LAI with narrow plant spacing in AMP2 and AMP4. Total fodder dry matter yield (DMY) in AMP2 and AMP4 with narrow plant spacing was significantly greater for both varieties. Furthermore, the DMY was not affected by fertilizer rate and irrigation interval.Value: Hybrid fodder sorghum varieties (SX-17 and Dairygreen) cultivated at higher plant density, along with reduced fertilizer (75%) and irrigation, can produce comparable fodder yield (21.1 and 26.1 MT/ha, respectively) to those grown at lower plant density with more fertilizer and irrigation (24.6 and 28.1 MT/ha, respectively) in lowland paddy fields during Yala and third seasons in the dry zone.

Radial distribution of heartwood extractives in second-growth western redcedar

Western redcedar has high economic value and has been traditionally used for cultural purposes by Indigenous communities. Second-growth redcedar is potentially growing faster due to lower planting densities, fertilization, and tree breeding. Little quantitative information is available about the impact of management practices on wood quality, particularly heartwood extractives. This study evaluated the effects of growth rate and site on heartwood extractives at two locations aged 70–90 years in British Columbia, Canada. A three-parameter sigmoid model was fit to the data using nonlinear mixed effects to analyze the relationship between heartwood extractives relative to cambial age, growth rate, and sampling site. The southern site had significantly higher cumulative extractive concentrations, while all extractive concentrations increased faster. This study shows that smaller trees will reach their peak concentrations earlier than larger trees. Results show that faster growth through active management of western redcedar may lead to increased and more uniformly distributed content of heartwood extractives.

Exploring Ecological, Morphological, and Environmental Controls on Coastal Foredune Evolution at Annual Scales Using a Process-Based Model

Coastal communities commonly rely upon foredunes as the first line of defense against sea-level rise and storms, thus requiring management guidance to optimize their protective services. Here, we use the AeoLiS model to simulate wind-driven accretion and wave-driven erosion patterns on foredunes with different morphologies and ecological properties under modern-day conditions. Additional sets of model runs mimic potential future climate changes to inform how both morphological and ecological properties may have differing contributions to net dune changes under evolving environmental forcing. This exploratory study, applied to represent the morphological, environmental, and ecological conditions of the northern Outer Banks, North Carolina, USA, finds that dunes experiencing minimal wave collision have similar net volumetric growth rates regardless of beach morphology, though the location and density of vegetation influence sediment deposition patterns across the dune profile. The model indicates that high-density, uniform planting strategies trap sediment close to the dune toe, whereas low-density plantings may allow for accretion across a broader extent of the dune face. The initial beach and dune shape generally plays a larger role in annual-scale dune evolution than vegetation cover. For steeper beach slopes and/or low dune toe elevations, the model generally predicts wave-driven dune erosion at the annual scale.

PROXIMATE ANALYSIS AND MINERAL PROFILE OF TARO (Colocasia esculenta) IN EMBU, KENYA

&lt;p&gt;&lt;strong&gt;Background.&lt;/strong&gt; Taro (&lt;em&gt;Colocasia esculenta&lt;/em&gt;) is one of the underutilized crops in Kenya, grown under a wide range of environmental and edaphic conditions. This crop has exceptional dietary value and numerous culinary applications due to its edible leaves and corms. However, the mineral nutrient composition of taro in Kenya is still not well known due to a lack of scientific information concerning production. &lt;strong&gt;Objective. &lt;/strong&gt;To determine the proximate composition and mineral profile of taro under different watering regimes and planting densities in Embu, Kenya. &lt;strong&gt;Methodology.&lt;/strong&gt; A study was conducted at the Kenya Agricultural and Livestock Research Organization (KALRO) – Embu Research Centre, during the long rains (LR) 2021, and short rains (SR) 2021/2022. A factorial experiment with a split-plot layout arranged in a completely randomized block design was adopted. The watering regimes (100 %, 60 %, and 30 % based on the field capacity (FC)) were the main factor while the sub-factor was the planting density, with three replications. The planting densities used were 0.5 m × 0.5 m (40,000 plants ha&lt;sup&gt;-1&lt;/sup&gt;), 1 m × 0.5 m (20,000 plants ha&lt;sup&gt;-1&lt;/sup&gt;), and 1 m × 1 m (10,000 plants ha&lt;sup&gt;-1&lt;/sup&gt;), representative of high, medium, and low planting densities respectively. Proximate analysis and mineral content were determined. &lt;strong&gt;Results.&lt;/strong&gt; Significant differences (&lt;em&gt;P &amp;lt; 0.05&lt;/em&gt;) in seasons were noted for protein, fibre, potassium, calcium, sodium, and zinc in the taro corms. The high carbohydrate content observed in this study (35 – 39 %) indicates that taro tubers are a good source of nutritional energy. Potassium (&amp;gt; 5000 mg kg &lt;sup&gt;-1&lt;/sup&gt;) and magnesium (&amp;gt; 1000 mg kg &lt;sup&gt;-1&lt;/sup&gt;) were the most prevalent mineral elements in taro corms and leaves, with copper (&amp;lt; 25 mg kg &lt;sup&gt;-1&lt;/sup&gt;) being the least prevalent. &lt;strong&gt;Implications.&lt;/strong&gt; Consumption of nutrient-rich foods such as taro helps the body to utilize the necessary nutrients to combat malnutrition and promote food security in rural communities. &lt;strong&gt;Conclusion.&lt;/strong&gt; Taro leaves can be recommended as leafy vegetables as they are good sources of potassium, magnesium, calcium, manganese, iron, copper, and zinc; and the corms have low fat and protein content, high calorific energy, and high carbohydrate content. Taro represents one of the main sources of energy in many parts of the tropics and its production can be recommended in sub-humid areas in Kenya.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;

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.

Influence of soil properties on woody vegetation structure, diversity and seasonality in Neotropical savannas

AbstractUnderstanding how savanna soil properties influence vegetation diversity and function is a major challenge in ecological studies. We investigated the effects of soil properties on woody species density, richness, composition, and vegetative phenology (inferred by the Normalized Difference Vegetation Index (NDVI)) in two alluvial and two interfluvial savanna sites (1 block of 10 plots of 20 × 50 m in each site), in the Brazilian Cerrado. We showed that plots in alluvial savannas present less fertile soils and have lower plant densities and species richness and higher seasonality of NDVI than plots in the interfluvial savannas. The species composition of the sites was associated with the P, Fe, K, and Mn content of the soil. Soil K, Fe, and Ca contents were the main variables associated with plant density in a linear mixed model (LMM) that explained 79% of data variability (r2c = 0.79%), and K, Fe, and Al were the main predictors to explain species richness (r2c = 0.81%). Soil K, pH, and Silt were the best predictors of the seasonality in NDVI (r2c = 0.14%). We highlight the all‐encompassing effect of K soil content on species density, richness, composition, and NDVI and argue that this macronutrient and a few other soil properties (e.g., P, Fe, Al, and Silt) are the main factors mediating plant responses to water and nutrient stress in woody savanna communities occurring in the Cerrado–Amazônia transition.

Effect of nitrogen fertilization levels and plant density on dry weight, yield components and bulb quality of onion plant

A field experiment was carried out during the two successive winter seasons of 2020/2021 and 2021/2022 to study the effect of mineral nitrogen levels and plant density on dry weight, yield and its components, as well as bulb quality of onions (cv. ‘Ahmar Tanawy’). This experiment included 12 treatments, which were combinations between four levels of mineral nitrogen (0, 192, 240 and 288 kg N/ha) and three plant densities (4, 5 and 6 rows/ridge equal 33.33, 41.67 and 50 plants/m2, respectively). These treatments were arranged in a split-plot design with three replications. Nitrogen levels were randomly arranged in the main plots, and plant densities were randomly distributed in the subplots. Nitrogen application at 192,244 and 288 kg N/ha led to increase dry weight/plant compared to control (zero N) and 288 kg N/ha gave the highest values of dry weight of leaves, dry weight of bulbs, and total dry weight per plant at 100 days in both seasons. The increases in total dry weight per plant were about 4.84 and 4.80 g per plant for 192 kg N/ha, 4.76 and 3.87 g per plant for 244 kg N/ha, and 6.86 and 5.74 g per plant for 288 kg N/ha over the control at 100 days in the 1st and 2nd seasons, respectively. The interaction between N at 288 kg/ha and low plant density (4 rows/ridge) gave the highest values of dry weight of leaves, bulb, and total dry weight/plant and increased yield of grade 1, exportable yield, average bulb weight, as well as nitrate and sulphur contents in bulbs, whereas the interaction between N at 244 kg/ha and high plant density (6 rows/ridge) increased grades 2, 3, and 4, marketable yield, and total yield/ha.