Journal of Agronomy and Crop Science最新文献

Light is a primary source of energy for photosynthesis and a fundamental signal that governs plant morphology and growth dynamics through well-orchestrated signalling pathways. In field conditions, light intensity and quality, as well as other variables, constantly change throughout the day. Therefore, field conditions introduce environmental variability that is difficult to simulate in controlled experiments. To address this challenge, we developed a standardised PhotoBiology Station (PBS) for studies on the complexities of plant–light interactions under field conditions. The station features five levels of shade and three replicates arranged in a randomised block design. The black shade nets linearly and significantly reduced the photosynthetically active radiation across shade levels. Spectral analysis revealed a consistent reduction in photon irradiance across the blue, green, red and far-red spectral bands, with a decrease in the blue/green ratio while maintaining a stable red/far-red ratio. Microclimatic conditions, including temperature and relative humidity, were also affected. Soybean seedlings exhibited typical shade-avoidance responses, such as increased stem height, coupled with reduced stem diameter. Multivariate analyses indicated that the blue light band acts as a signal that triggers plant responses to shade under the black shade net. These findings validate PBS as an effective platform for studying shading effects and plant–light interactions under open-air conditions and overcome critical methodological challenges, such as pseudoreplication. Furthermore, this study provides a robust analytical framework for dissecting complex plant–light dynamics in situ, also revealing the importance of accurately characterising light intensity and spectral profiles in shading experiments. Finally, PBS helps to bridge the gap between laboratory findings and practical agricultural applications.

Flooding is a major abiotic stress that limits legume productivity and ecological resilience. Identifying variation in submergence tolerance among legume accessions is critical for developing climate-resilient cultivars. This study investigated phenotypic and physiological responses to complete submergence in nine Lotus japonicus accessions, selected from a range of latitudes, subjected to 10 days of submergence followed by recovery. Growth traits (leaf area, dry biomass), chlorophyll fluorescence (Fv/Fm) and reproductive timing (flowering onset and cumulative flower production) were assessed relative to non-flooded controls. We hypothesised that developmental traits would vary in response to complete submergence. Submergence induced significant mean reductions in biomass (−36.9% ± 3.9%) and photosystem II efficiency (−27.4% ± 2.6%), though all accessions fully recovered photosynthetic function within 10 days post-flood. Surprisingly, the accessions displayed two contrasting adaptive strategies: six exhibited growth arrest consistent with a low-oxygen quiescence response, while three maintained shoot elongation under water, indicative of an escape strategy. The negative correlation between change in leaf area during submergence and early recovery growth suggested a physiological trade-off. Accessions also displayed different responses in terms of flowering time with mean delays of between 0.5 and 21 days. Flooding also reduced cumulative flower production by 24.8% ± 3.9%. Notably, there was a strong correlation between latitude and flowering time delay caused by submergence stress. These results reveal substantial intra-specific variation in submergence responses among L. japonicus accessions and demonstrate the utility of this species as a model for dissecting stress-tolerance mechanisms in Fabaceae. The findings could inform breeding strategies for improved flood resilience in forage and grain legumes.

Drought is a major abiotic stress affecting crop yields worldwide. Similarly, organic practices have been reported to enhance soil health and microbial diversity, influencing crop growth and yield. Given its drought tolerance, spelt (Triticum spelta) has been proposed as a resilient alternative to wheat (Triticum aestivum). Nevertheless, its agronomic and microbial responses under water-limited conditions within different farming systems remain poorly understood. This study compares wheat and spelt under irrigated and rainfed environments using conventional and organic farming practices in the field. Spelt showed greater resilience to water-limited conditions, maintaining yield, grain weight, and exhibiting higher antioxidant capacity under rainfed. Wheat yields dropped by 17% under rainfed but still remained 229% higher than spelt. Under organic farming, yields were 57%–85% and 77%–85% lower in spelt and wheat, linked to lower nitrogen availability. This provoked higher grain C/N ratios, indicating lower nutritional quality. Analysing belowground microbial ecosystem, farming practice was the primary factor explaining the dissimilarity of microbial community composition, with the irrigation regime playing a secondary role. Concretely, organic practices promoted the enrichment of soil bacterial microorganisms involved in nitrogen cycling and organic matter degradation, including members of Nitrosococcaceae SZB85, Thermomicrobiaceae, and Actinomycetospora; however, this was not enough to increase nitrogen availability and promote plant yield. On the other hand, under rainfed, specifically in conventional soils, the potentially pathogenic species Ustilago maydis increased, while both wheat and spelt simultaneously recruited beneficial species for plant development, Chrysosporium pseudomerdarium. Similarly, in organic soils experiencing water-limited conditions, an increase in beneficial microorganisms like Paraphoma radicina and Rhizopus arrhizus was also observed. Our findings highlighted the potential of spelt as a drought-tolerant alternative in water-limited regions while also revealing the limitations of organic farming practices for yield.