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Modern agriculture faces the challenge of increasing production without expanding cultivated areas, promoting sustainable practices that ensure food security and environmental preservation. Integrated crop–livestock systems (ICLSs) stand out as an effective strategy, diversifying and intensifying agricultural production in a sustainable manner, ensuring adequate soil cover, and improving nutrient cycling efficiency. Thus, this study aimed to explore and compare integrated crop–livestock systems with Zuri guinea grass (Panicum maximum cv. BRS Zuri) and Quênia guinea grass (Panicum maximum cv. BRS Quênia) against the conventional soybean/maize succession method in a tropical region, and how these systems affect biomass decomposition, C:N ratio, nutrient cycling, and fertilizer equivalents. A field experiment was conducted in two phases: the first in the second-crop season and the second in the main season, using a randomized block design with four replicates. The treatments consisted of two ICLS systems, one with Zuri and Quênia guinea grasses established after soybean, and a succession system with maize established after soybean. The results indicated that Quênia guinea grass showed greater desiccation efficiency, with an injury rate of 86.5% at 21 days, 8.5% higher compared to Zuri guinea grass. In terms of biomass, Zuri and Quênia guinea grasses had average productions of 7021.1 kg ha−1, which was 43.25% higher compared to maize biomass. The biomass decomposition of the grasses was faster due to their lower C:N ratio, resulting in greater nutrient release into the soil. Both forage grasses (Zuri and Quênia guinea grasses) are suitable for integrated crop–livestock systems, as they showed similar biomass production and nutrient accumulation. Soybean yield was not influenced by the different cropping systems, showing similar results between the biomass of Zuri and Quênia guinea grasses and maize. However, grass biomass enriches the soil more through the return of fertilizer equivalents, which in future studies could be considered for the reduction of mineral fertilizers, ensuring greater sustainability of agricultural systems.

This study investigates the production and nutritional quality of Panicum maximum cv. Mombasa grass under varying levels of water stress and nitrogen (N) fertilization, aiming to enhance forage production in harsh environments. Four irrigation levels (5760, 6912, 4608, and 3456 m3 ha−1 year−1) and three N fertilizer doses (115, 57.5, and 0 kg ha−1 year−1) were tested. The results indicate that Mombasa grass produced higher fresh and dry weights under higher irrigation levels (I1 and I2) compared to water deficit conditions across all cuts. Interestingly, under moderate water stress (I3), the dry weight was not significantly different from that under higher irrigation for the sixth harvest in the first season. Water deficit conditions led to a significant reduction in protein content across all treatments. However, under lower irrigation levels (I3 and I4), there was a significant increase in phosphorus (P), potassium (K₊), iron (Fe2₊), and zinc (Zn) concentrations. A heatmap analysis of shape descriptors grouped the productivity and nutritional traits into two clusters based on their response to combined fertilization and drought stress. This analysis revealed that the dry weight, number of leaves, and Fe and Zn contents were positively affected under moderate water stress (80% of control; 4608 m3 ha−1 year−1) with recommended N fertilization. The study concludes that Panicum maximum cv. Mombasa is tolerant to moderate water stress and is suitable for forage production in the Qassim region, Saudi Arabia.

The objective of this study was to evaluate the production and chemical composition of three forage species at different regrowth intervals. A 3 x 4 randomized-block factorial design with three forage species (Andropogon, Buffel, and Massai) and four regrowth intervals (21, 35, 49, and 63 days) was used. There was no interaction (p > 0.05) between forage species and regrowth interval on any of the chemical components evaluated. The crude protein content decreased but the contents of neutral detergent fiber, acid detergent fiber and hemicellulose increased with increasing regrowth interval (p > 0.05). Only the contents of crude protein and ether extract were similar (p > 0.05) among grasses. A significant interaction was observed (p < 0.05) between forage species and regrowth interval on forage mass. Andropogon grass had the highest forage mass at 63 days (3,270.1 kg ha-1 DM cut-1) and the highest productivity regardless of the regrowth interval (19.1 t ha-1 DM year-1). Therefore, Andropogon grass was the most productive forage among the tested species. Pastures should be managed with shorter growth intervals due to the highest crude protein level and the lowest contents of neutral detergent fiber and acid detergent fiber.

This study was designed to evaluate the effect of substituting alfalfa hay with graded levels panicum maximum without or with graded levels of spirulina supplementation on rumen fermentation and nutrient degradability. The evaluation was achieved through an in vitro study, rumen fluid was obtained from adult sheep aged 2 years (fed clover hay), immediately after slaughter. Experimental diets were formulated as isonitrogenous and isocaloric and contained 40% forage. Forage composition was altered by substituting alfalfa hay with graded levels of panicum maximum hay, so that treatment diets contained 0, 25, 50, 75, and 100% of the forage from panicum maximum for treatments R1, R2, R3, R4, and R5, respectively. Additionally, each treatment was further supplemented with graded levels of spirulina at the following rates: 0, 0.5, 1.5, 2, 2.5, and 3 mg/g. Results indicated that gas production after 24 h per g DM, OM and DDM has a positive linear relationship with spirulina supplementation level (R 2  = 0.80, 0.83, and 0.93, respectively). The gas production increased by increasing the level of Spirulina. However negative linear relationships were recorded between gas production per g DM, OM, DDM and alfalfa substitution level (R 2  = 0.97, 0.95, and 0.96, respectively) which the gas production decreased as the substitution level increased. In vitro degradability of dry and organic matter was decreased by the increment of Panicum maximum and Spirulina supplementation levels and vice versa, until 2 mg/g of Spirulina ( p  < .0001). The addition of Spirulina significantly ( p  < .0001) increased total volatile fatty acids (TVFA) and NH 3 concentration, until 2mg/g, while the addition of Panicum maximum hay significantly increased NH 3 concentration, until it reached at (R4). In conclusion, the substitution of alfalfa hay with graded levels of Panicum maximum hay may be reduce nutrients degradability and gas production while supplementing diets with graded level of spirulina improve degradability and ruminal fermentation parameters.

This study aimed to evaluate the morphogenic and structural characteristics of six Panicum maximum cultivars during the establishment period. A completely randomized block design with four replicates and six treatments (Tamani, Mombaça, Massai, Tanzania, Aruana and Zuri cultivars) was used. Morphogenic (leaf appearance rate, leaf elongation rate e stem elongation rate), structural (final leaf length, tiller population density e number of leaves per tiller) and productive (forage mass, leaf blade mass, stem mass, senescent material mass and leaf:stem ratio) characteristics were evaluated. There was no difference (p > 0.05) between the cultivars in terms of the number of live leaves per tiller (2.95 leaves/tiller). Mombaça cultivar had (p < 0.05) higher canopy height (50.64 cm) compared with other cultivars. The highest (p < 0.05) tiller population density was observed in Tamani (235.90 tillers m-2) and Massai (201.60 tillers m-2) cultivars. Leaf lifespan (54.18 days), phyllochron (17.40 days/leaf) and leaf senescence rate (0.87 cm tiller day-1) were not different (p > 0.05) between cultivars. However, leaf appearance rate was higher (p < 0.05) in Tanzania (0.07 leaves tiller day-1) than in Aruana cultivar (0.05 leaves tiller day-1). Leaf blade mass was higher (p < 0.05) in Mombaça cultivar (1518.31 kg DM ha-1), whereas Massai showed higher (p < 0.05) leaf:stem ratio (9.25). Panicum cultivars Tamani, Tanzania and Massai establishment after 75 days, while the other cultivars establish at 105 days of sowing in the Brazilian Northeast.

The use of cover crops in no-tillage systems (NTS) can significantly improve the soil's fertility. Thus, a study was performed to evaluate changes in chemical properties of soil caused by cover crops in a no-tillage system. The field experiment consisted of the following crop rotation: cover crops/rice/cover crops/rice. The experimental design was in randomized blocks with three replications. Treatments consisted of four cover crops (Brachiaria brizantha(Hochst. ex A. Rich.) Stapf. cv. Marandu, Brachiaria ruziziensis R. Germ. and C.M. Evrard, Panicum maximum Jacq. cv. Colonião, and Pennisetum glaucum(L.) R. Br. cv. BN-2) and fallow (control treatment). Soil samples were collected at the beginning of the summer crop in Oct 2007, Oct 2008 and Oct 2009 at 0-5 cm soil depth. The use of cover crops provided for a significant increase in the level of nutrients, soil organic matter, cation exchange capacity, and base saturation in the soil. Soil fertility improved from the first to second year with the growing of cover crops. The soil under cover crops P. glaucum, B. ruziziensis, and B. brizantha showed higher fertility than the area under fallow. O uso de plantas de cobertura no sistema de plantio direto (SPD) pode melhorar significativamente a fertilidade do solo. Assim, um estudo foi realizado para avaliar as alterações nas propriedades químicas do solo causadas pelas culturas de cobertura em sistema de plantio direto. O experimento de campo consistiu na rotação das seguintes culturas: plantas de cobertura/ arroz/ plantas de cobertura/ arroz. O delineamento experimental foi em blocos casualizados com três repetições. Os tratamentos consistiram de quatro espécies de plantas de cobertura (Brachiaria brizantha(Hochst. ex A. Rich.) Stapf. cv. Marandu, Brachiaria ruziziensis R. Germ. and C.M. Evrard, Panicum maximum Jacq. cv. Colonião and Pennisetum glaucum(L.) R. Br. cv. BN-2) e pousio (tratamento controle). As amostras foram coletadas no início da safra de verão, em outubro de 2007, 2008 e 2009, a 0-5 cm de profundidade. O uso de plantas de cobertura proporcionou aumento significativo na concentração de nutrientes, matéria orgânica do solo, capacidade de troca catiônica e saturação por bases. A fertilidade do solo melhorou do primeiro para o segundo ano com o cultivo de plantas de cobertura. O solo sob as plantas de cobertura P. glaucum, B. ruziziensis e B. brizantha apresentou maior fertilidade do que a área mantida sob pousio.

Potassium (K) is essential for the productivity of tropical grasses, but its optimal supply remains unclear. This study evaluated the effects of K on gas exchange, photosynthetic rate (A), forage production (FP), and root development (RP) in Panicum maximum cultivars. The experiment was conducted using a randomized block design in a 6 × 4 factorial scheme (six cultivars: Tanzânia, Quênia, Mombaça, Zuri, Massai and Tamani; and four K rates: 0, 205, 410 and 820 mg dm −3 ). There was interaction between cultivars and K rates for A and stomatal conductance (g s ), with linear increases in A for all cultivars. The g s response in the Zuri cultivar was quadratic, with a maximum of 5.32 mmol m −2  s −1 at the dose of 410 mg dm −3  K, and linear for the other cultivars. The CO 2 concentration (Ci) and leaf temperature (Tleaf) were not influenced by the K dose or by the cultivars, maintaining an average of 129.28 ppm and 29.32 °C, respectively. Transpiration (E) increased by 0.018 mmol m −2  s −1 with increasing K doses. The chlorophyll content fitted a quadratic model, with a maximum of 35 SPAD at the dose of 530 mg dm −3 . The FP increased linearly for all cultivars, with the highest FP in the cultivars Quênia, Mombaça and Zuri. Increasing K doses improved A and g s , reflecting in higher FP. The cultivars Quênia and Mombaça showed the greatest increases in FP up to 820 mg dm −3  K, while the maximum efficiency for RP occurred between 205 and 410 mg dm −3 , suggesting that excessive K supply may not proportionally increase root development.

Changes in leaf anatomy and ultrastructure are associated with physiological performance in the context of plant adaptations to climate change. In this study, we investigated the isolated and combined effects of elevated atmospheric CO2 concentration ([CO2]) up to 600 μmol mol-1 (eC) and elevated temperature (eT) to 2°C more than the ambient canopy temperature on the ultrastructure, leaf anatomy, and physiology of Panicum maximum Jacq. grown under field conditions using combined free-air carbon dioxide enrichment (FACE) and temperature free-air controlled enhancement (T-FACE) systems. Plants grown under eC showed reduced stomatal density, stomatal index, stomatal conductance (gs), and leaf transpiration rate (E), increased soil-water content (SWC) conservation and adaxial epidermis thickness were also observed. The net photosynthesis rate (A) and intrinsic water-use efficiency (iWUE) were enhanced by 25% and 71%, respectively, with a concomitant increase in the size of starch grains in bundle sheath cells. Under air warming, we observed an increase in the thickness of the adaxial cuticle and a decrease in the leaf thickness, size of vascular bundles and bulliform cells, and starch content. Under eCeT, air warming offset the eC effects on SWC and E, and no interactions between [CO2] and temperature for leaf anatomy were observed. Elevated [CO2] exerted more effects on external characteristics, such as the epidermis anatomy and leaf gas exchange, while air warming affected mainly the leaf structure. We conclude that differential anatomical and physiological adjustments contributed to the acclimation of P. maximum growing under elevated [CO2] and air warming, improving the leaf biomass production under these conditions.

Panicum maximum Jacq. 'Mombaca' (C4) was grown in field conditions with sufficient water and nutrients to examine the effects of warming and elevated CO2 concentrations during the winter. Plants were exposed to either the ambient temperature and regular atmospheric CO2 (Control); elevated CO2 (600 ppm, eC); canopy warming (+2 degree C above regular canopy temperature, eT); or elevated CO2 and canopy warming (eC+eT). The temperatures and CO2 in the field were controlled by temperature free-air controlled enhancement (T-FACE) and mini free-air CO2 enrichment (miniFACE) facilities. The most green, expanding, and expanded leaves and the highest leaf appearance rate (LAR, leaves day-1) and leaf elongation rate (LER, cm day-1) were observed under eT. Leaf area and leaf biomass were higher in the eT and eC+eT treatments. The higher LER and LAR without significant differences in the number of senescent leaves could explain why tillers had higher foliage area and leaf biomass in the eT treatment. The eC treatment had the lowest LER and the fewest expanded and green leaves, similar to Control. The inhibitory effect of eC on foliage development in winter was indicated by the fewer green, expanded, and expanding leaves under eC+eT than eT. The stimulatory and inhibitory effects of the eT and eC treatments, respectively, on foliage raised and lowered, respectively, the foliar nitrogen concentration. The inhibition of foliage by eC was confirmed by the eC treatment having the lowest leaf/stem biomass ratio and by the change in leaf biomass-area relationships from linear or exponential growth to rectangular hyperbolic growth under eC. Besides, eC+eT had a synergist effect, speeding up leaf maturation. Therefore, with sufficient water and nutrients in winter, the inhibitory effect of elevated CO2 on foliage could be partially offset by elevated temperatures and relatively high P. maximum foliage production could be achieved under future climatic change.

1-Aminocyclopropane-1-carboxylic acid (ACC) is a precursor molecule of ethylene whose concentration is elevated in the plant subjected to biotic and abiotic stress. Several soil microorganisms are reported to produce ACC deaminase (ACCd) which degrades ACC thereby reducing stress ethylene in host plants. This study is aimed to apply ACCd producing beneficial rhizobacteria to improve biochemical parameters and cell wall properties of Panicum maximum exposed to salt and drought stress, focusing on bioethanol production. Thirty-seven ACCd producing bacteria isolated from rhizospheric soil of field grown P. maximum and 13 were shortlisted based on their beneficial traits (root colonization, production of indole acetic acid, siderophore, hydrogen cyanide, phosphate solubilization, biofilm formation, tolerance to salt and Polyethylene glycol) and a total score obtained. All shortlisted bacteria were found significant in enhancing the plant growth, water conservation, membrane stability, biocompatible solutes and protein, phenolic contents and photosynthetic pigments in plants grown under stress conditions. Cell wall composition (Cellulose, Hemicellulose and Lignin) of the treated plants grown under stress conditions recorded a significant improvement over their respective controls and found equivalent to the plants grown under normal circumstances. Biomass from bacterial treatment recorded higher total reducing sugars upon pre-treatment and hydrolysis, and theoretical bioethanol yield.