Intercropping legumes with cereals can lead to increased overall yield and optimize the utilization of resources such as water and nutrients, thus enhancing agricultural efficiency. Legumes possess the unique ability to acquire nitrogen (N) through both N₂ fixation and from the available N in the soil. However, soil N can diminish the N₂ fixation capacity of legumes. It is postulated that in intercropping, legumes uptake N mainly through N₂ fixation, leaving more soil N available for cereals. The latter, in turn, has larger root systems, allowing it to explore greater soil volume and absorb more N, mitigating its adverse effects on N₂ fixation in legumes. The goal of this study was to evaluate how the supply of N affects the intercropping of faba beans (Vicia faba L.) and peas (Pisum sativum L.) with wheat under varying plant densities and N levels. We measured photosynthetic traits, biomass production, the proportion of N derived from air (%Ndfa) in the shoot of the legumes, the N transferred to the wheat, and the land equivalent ratio (LER). The results revealed a positive correlation between soil N levels and the CO₂ assimilation rate (An), chlorophyll content, and N balance index (NBI) in wheat. However, no significant effect was observed in legumes as soil N levels increased. Transpiration (E) increased in wheat intercropped with legumes, while stomatal conductance (g_s) increased with N addition in all crops. Water use efficiency (WUE) decreased in faba beans intercropped with wheat as N increased, but it showed no significant change in wheat or peas. The shoot dry matter of wheat increased with the addition of N; however, the two legume species showed no significant changes. N addition reduced the %Ndfa of both legume species, especially in monoculture, with peas being more sensitive than faba beans. The intercropping of wheat alleviated N₂ fixation inhibition, especially at high wheat density and increased N transfer to wheat, particularly with peas. The LER was higher in the intercropping treatments, especially under limited N conditions. It is concluded that in the intercropping of wheat with legumes, the N₂ fixation inhibition caused by soil N is effectively reduced, as well as there being a significant N transfer from the legume to the wheat, with both process contributing to increase LER.

The phenotypic diversity and productivity of a diverse alfalfa (M. sativa subspp.) panel of cultivars, landraces and wild relatives with putative drought tolerance were evaluated in two Mediterranean environments (central Chile and Southern Australia). In Chile, 70 accessions were evaluated in rainfed conditions and in Australia 30 accessions under rainfed and irrigated conditions, during three growing seasons. Large phenotypic variation was observed among and within subspecies for NDVI, stem length, intercepted PAR and forage yield. Principal component analysis indicated that the first two principal components (PC) accounted for 84.2% of total variance; fall dormancy, taxa, and breeding status were closely related to the agronomical performance of alfalfa accessions. Forage yield varied largely among accessions across years and locations. A linear relationship was found between annual forage yield and annual water added to the experiments (R² = 0.60, p < 0.001). The GxE analysis for forage yield allowed the detection of the highest yielding accessions for each of the two mega-environments identified. The accessions CTA002 and CTA003 showed greater forage yield in both Chile and Australia environments. It is concluded that new breeding lines derived from crosses between cultivated alfalfa (M. sativa subsp. sativa) and wild relatives belonging to the primary (M. sativa subsp. falcata) and tertiary (M. arborea) gene pool, achieve outstanding agronomical performance in drought-prone environments.

Alfalfa is a deep-rooted perennial forage crop with diverse drought-tolerant traits. This study evaluated 250 alfalfa half-sib populations over three growing seasons (2021–2023) under irrigated and rainfed conditions in the Mediterranean drought-prone region of Central Chile (Cauquenes), aiming to identify high-yielding, drought-tolerant populations using remote sensing. Specifically, we assessed RGB-derived indices and canopy temperature difference (CTD; Tc − Ta) as proxies for forage yield (FY). The results showed considerable variation in FY across populations. Under rainfed conditions, winter FY ranged from 1.4 to 6.1 Mg ha⁻¹ and total FY from 3.7 to 14.7 Mg ha⁻¹. Under irrigation, winter FY reached up to 8.2 Mg ha⁻¹ and total FY up to 25.1 Mg ha⁻¹. The AlfaL4-5 (SARDI7), AlfaL57-7 (WL903), and AlfaL62-9 (Baldrich350) populations consistently produced the highest yields across regimes. RGB indices such as hue, saturation, b*, v*, GA, and GGA positively correlated with FY, while intensity, lightness, a*, and u* correlated negatively. CTD showed a significant negative correlation with FY across all seasons and water regimes. These findings highlight the potential of RGB imaging and CTD as effective, high-throughput field phenotyping tools for selecting drought-resilient alfalfa genotypes in Mediterranean environments.

The espinal agroforestry system is a valuable grazing resource for sheep and cattle in the Mediterranean region of central Chile. It is characterized by a woody stratum dominated by Vachellia caven and an herbaceous grassland stratum that together provide important ecological services. Despite its relevance for extensive livestock production, ongoing land-use change threatens the integrity of the espinal agroforestry system, underscoring the need for sustainable management strategies to enhance productivity. This study assessed the long-term impacts of improved management practices in a representative espinal agroforestry system, including annual fertilization, supplementary cereal crop integration, and progressive increases in stocking rate, on plant diversity and soil carbon storage in Cauquenes, Maule Region, Chile (35°58′ S, 72°17′ W), during 2014–2019. A production system was established on 10 ha of espinal grassland, complemented by 1 ha of supplementary crop rotation (oat–purple vetch intercropping and triticale). Due to the scale of the system, a single experimental unit was used; however, multiple sampling areas were evaluated over time to assess the botanical composition, forage yield, and soil carbon. Grasslands were annually fertilized with phosphorus, potassium, and boron. The forage yield in spring ranged from 2 to 4 t dry matter ha⁻¹ year⁻¹ over six years, with strong interannual variability driven by rainfall. The stocking rate increased progressively from 2 to 8 sheep ha⁻¹ and lamb live weight from 80 to 370 kg ha⁻¹ over six-years. The grassland botanical composition shifted markedly, with increased abundance of annual legumes (Trifolium subterraneum, Medicago polymorpha) and Leontodon leysseri. Supplementary crops yielded between 6.0 and 10.5 t DM ha⁻¹, while soil organic carbon increased from 1.6% to 2.2%. These results demonstrate that sustainable intensification of the espinal system can enhance productivity while maintaining environmental sustainability.