Research Frontiers: Agronomy Research & Applications

Integrating Green Manures and Sweet Sorghum into Sugarcane Rotations Enhances Yield and Sandy-Soil Hydrophysical Properties

2026-08-25T04:51:27+00:00

Sugarcane is the leading feedstock for bioethanol in Brazil and worldwide, but its continuous cultivation can degrade soil through nutrient depletion and compaction. Integrating green manures such as Crotalaria and pigeon pea into rotations offers a sustainable way to improve soil structure, water infiltration, and nutrient cycling. When combined with sweet sorghum as a complementary crop, these species can mitigate soil physical constraints and strengthen the resilience of sugar–energy systems under rainfed conditions. This three-year field experiment evaluated the effects of green manure and sweet sorghum rotations on sugarcane yield and sandy-soil physical attributes. The treatments were arranged in a 3 × 2 factorial design with randomized blocks, including two green manures (Crotalaria and pigeon pea) and a fallow control, each combined with or without sweet sorghum rotation. Biometric traits and yields were measured for all crops, and soil physical properties were assessed after the sugarcane cycle. Green manure significantly increased the stalk yield and dry matter of both sweet sorghum and sugarcane. In sugarcane, rotations with Crotalaria and pigeon pea enhanced stalk and dry matter yields by up to 18%, while the highest increase (31%) occurred under the sweet sorghum rotation. Furthermore, green manures improved sandy-soil water retention, increased infiltration rates, and reduced penetration resistance. These results demonstrate that legume–sorghum rotations are an effective and low-input strategy to enhance crop yield and sandy-soil physical properties, contributing to more sustainable bioenergy production under tropical rainfed conditions.

Impact of Nitrogen and Sulphur Fertilisation on Phosphorus and Silicon Content and Uptake by Biomass of Spring Wheat

2026-05-14T06:55:34+00:00

Nitrogen and sulphur are among the most important plant nutrients (along with C, H, and O) and the main elements comprising the organic substance of plants. In this study, it is assumed that light soils (Cambisols) do not naturally meet the nitrogen and sulphur needs of spring wheat and, consequently, impact the phosphorus and silicon content in the plant biomass. Therefore, to determine the effect of N and S on the content and uptake of these elements at specific growth stages (BBCH 30–31: in leaves, BBCH 55–59: in whole plants, BBCH 89–90: in grain and straw), a three-year field experiment was conducted using different doses of nitrogen (0, 40, 80, and 120 kg ha⁻¹) and sulphur (0, 50 kg ha⁻¹). The results show that fertilisation with N and S had a significant effect on increasing the content and uptake of P and Si by phytomass in the phenostages studied. In general, as the N fertilisation dose increased, the yields of phytomass and grain increased. A beneficial effect of S on increases in green weight, straw, and spring wheat grain was found. A significant effect of N and S fertilisation on the growth of the Si:P ratio in individual parts of plants in the studied stages was also observed. A significant positive correlation between P and Si content was proven, indicating that the two elements do not act antagonistically towards each other. In contrast, a negative correlation was observed between the P content in plants and their Si uptake. Si is taken up more strongly by plants under conditions of N and S fertilisation, as evidenced by the increase in the Si:P ratio and the fact that plants accumulated on average 3.5 times more Si than P. The highest Si content was found in the green parts of plants in the BBCH 30–31 and BBCH 55–59 stages, while in BBCH 89–92, straw had nearly half that amount and grain contained a thousand times less silicon.

Yield Prediction of Winter Wheat (Triticum aestivum) Varieties Using UAV-Derived Multispectral Vegetation Indices Across Growth Stages

2026-08-25T04:59:03+00:00

This study investigates the potential for early yield prediction in nine winter wheat (Triticum aestivum) varieties using multispectral data acquired at different growth stages. The data were collected using an unmanned aerial vehicle (UAV) equipped with a multispectral sensor including a near-infrared (NIR) band and an RGB camera. An assessment of data acquisition and processing accuracy was conducted. The average ground sampling distance (GSD) was 0.42 cm, compared to the pre-flight planned value of 0.54 cm/pixel. The total processing error ranged between 0.34% and 0.45% of a pixel. Five vegetation indices were analyzed, including three NIR-based indices (NDVI, EVI2, and SAVI) and two RGB-based indices (MPRI and MGVRI). The strongest relationships between yield and NIR-based indices were observed on 26 April (spindle phase), with coefficients of determination (R²) ranging from 0.98 to 0.99, while the weakest relationships occurred in late March (R² = 0.75–0.80). In contrast, RGB-based indices showed the strongest correlation in early December (R² = 0.99) and the weakest on April 26 (R² = 0.38–0.40). Regression models for yield prediction were developed based on both groups of vegetation indices. The results demonstrate that the predictive capability of vegetation indices varies significantly across growth stages, highlighting the importance of temporal data selection for accurate yield estimation.

Biomass Production and Nitrogen Accumulation of Summer Cover Crop Mixtures Under Two Sowing Dates in a Cool Temperate Climate

2026-08-24T04:18:44+00:00

Summer cover crops can improve soil fertility and contribute to nitrogen (N) supply in temperate cropping systems, yet the effects of mixture composition and sowing timing remain insufficiently documented. This study evaluated biomass production and N accumulation of five multispecies cover crop mixtures grown in Estonia during 2024–2025 under two sowing dates per year. Aboveground biomass, botanical composition, and carbon (C) and nitrogen concentrations were measured to assess productivity, species contributions, and residue quality. Earlier sowing was generally associated with higher biomass and N accumulation, with first-sown mixtures producing, on average, 38.7% more biomass than later-sown mixtures. Mixture performance was strongly shaped by species composition and competitive hierarchies. Total N accumulation of the cover crop mixtures ranged from 42 to 275 kg N ha⁻¹ depending on mixture composition and sowing time, with mixtures dominated by common vetch (Vicia sativa L.) achieving the highest values. Oat (Avena sativa) dominated and contributed substantially to biomass in mixtures lacking competitive legumes, whereas sunflower (Helianthus annuus) and maize (Zea mays) performed less well under delayed sowing. Low-growing species such as Persian clover (Trifolium resupinatum) produced little biomass when grown with highly competitive species. Legumes exhibited lower C:N ratios than non-legumes, while mixture-level values remained moderate, suggesting residue quality with potential for favourable decomposition and nutrient release in summer cover crop systems under temperate conditions.

Optimization of Key Techniques for In Vitro Rapid Propagation of New Edible and Ornamental Lily Cultivars

2026-08-25T05:11:19+00:00

Lilium, a traditional plant with dual medicinal and ornamental values, is restricted in its industrial development by the low natural propagation rate of bulbs and dependence on imported high-quality germplasm. To address this bottleneck, this study used new lines of LA hybrid lilies and Asiatic hybrid lilies (three cultivars) as experimental materials to establish an efficient and stable tissue culture and rapid propagation system. Key procedures including disinfection of different explants (bulb scales and capsules), adventitious bud induction and proliferation, rooting culture, as well as acclimatization and transplantation were systematically evaluated. The results showed that bulb scales were superior to capsule seeds as explants in tissue culture (contamination rate 9.44%, regeneration rate 11.92%). After disinfection with 75% ethanol combined with 10% sodium hypochlorite, the contamination rate could be controlled at 14.29–21.43%, and the regeneration rate reached 100%. Supplementation with 50 g·L⁻¹ sucrose + 1 mg·L⁻¹ 6-BA + 0.1 mg·L⁻¹ NAA (Treatment TA1), 50 g·L⁻¹ sucrose + 2 mg·L⁻¹ 6-BA + 0.5 mg·L⁻¹ NAA (Treatment TA4) in MS medium, combined with dark culture, could effectively promote adventitious bud induction, proliferation and bulblet enlargement. For the rooting stage, the optimal media were 1/2 MS + 0.5 g·L⁻¹ activated charcoal + 2 mg·L⁻¹ 6-BA + 0.5 mg·L⁻¹ NAA (Treatment TB4) or MS + 0.3 g·L⁻¹ activated charcoal + 2 mg·L⁻¹ 6-BA + 0.5 mg·L⁻¹ NAA (Treatment TB1), and the highest rooting rate of ‘Pink Renault’ reached 100%. When plantlets from all three cultivars were combined and acclimatized and transplanted into sterilized peat soil, the overall survival rate was 89.33%. The TOPSIS method was also adopted for comprehensive evaluation to screen out the optimal culture conditions for different varieties. Based on phenotypic observation and physiological index data, ‘Pink Renault’ showed great potential as an excellent propagation germplasm. The integrated and optimized technical system provides a feasible solution for large-scale and industrialized seedling production of medicinal and ornamental lilies, and is of great practical significance for the efficient utilization of germplasm resources and sustainable development of the lily industry.