The objective of this study was to verify the efficiency of two portable chlorophyll meters (Minolta SPAD^® 502 and Falker ClorofiLOG^® 1030) in assessing the nutritional status of wheat plants, correlating the indices from the devices and the direct determination of chlorophyll content with the concentration of nitrogen (N) in the plant. The experiment was conducted in a greenhouse, in pots with 5 dm³ of Oxisol, in a completely randomized design, with six N doses (0, 80, 160, 240, 320 and 400 mg dm^-3) and five replicates. At 47 days after emergence, the readings of SPAD and Falker indices and the quantification of chlorophyll content and N concentration in wheat plants were performed, as well as analysis of variance and correlation test, both at 0.05 probability level. The chlorophyll meters Minolta SPAD^® 502 and Falker ClorofiLOG^® 1030 do not differ with respect to the indirect determination of chlorophyll in wheat plants. The Falker chlorophyll index was statistically equal to the chlorophyll content. Indirect chlorophyll indices and chlorophyll content showed a high correlation with the N concentration in the plant.

Brazil is one of the world’s largest producers of beef cattle and dairy products, which requires high forage yield to attend grass-fed animals’ demand. Among the grass species adopted in the forage production system in Brazil, the Brachiaria genus stands out. This genus comprises nearly 85% of all planted forage area. In general, forage production systems in Brazil are essentially rainfed, and thus susceptible to seasonal soil water stresses. Selecting the suitable Brachiaria cultivar for lands susceptible to periodic waterlogging and dry spells is crucial to enhance forage yield, and consequently, to reduce the environmental footprint of the livestock sector. In this research, we investigated the performance of three recent commercial Brachiaria brizantha cultivars (Piatã, BRS Paiaguás, and MG13 Braúna) extensively adopted in Brazil’s grazing systems subjected to different ranges of soil water potential. For three cutting periods, yield related-variables (e.g., plant height, leaf area, dry biomass, and water use efficiency) were measured. Our results point to the existence of a low drought-resistant trait among cultivars, indicating the need for releasing better-adapted cultivars to cope with reduced soil water availability. All cultivars achieved higher performance at soil water pressure head between −15 kPa and −25 kPa; and in general, the cultivar. Piatã showed slightly superior results to most of the treatments.

This study aimed to evaluate the production and mineral nutrition of Piatã grass as a function of nitrogen and potassium fertilization in Oxisol collected in the Cerrado. The experiment was carried out in a greenhouse, the experimental design was completely randomized, in a 5 x 5 factorial scheme, corresponding to five nitrogen doses (0, 100, 200, 300 and 400 mg dm^-3 of N) and five potassium doses (0, 90, 180, 270 and 360 mg dm^-3 of K₂O), with four replicates. Three cuts of the shoots were performed every 30 days. Chlorophyll index, dry mass of shoots and roots, and nitrogen and potassium contents in the leaves were evaluated. The dry mass of shoots showed interaction between nitrogen and potassium in the three cuts; in the second and third cuts, it had maximum production at the nitrogen and potassium doses of 254 and 158 mg dm^-3, in the second, and 250 and 306 mg dm^-3 in the third, respectively. The nitrogen and potassium contents are influenced as a function of nitrogen and potassium fertilization isolated by factor. The nitrogen and potassium ratio in the Piatã grass crop was around 1:1.

Fertilization management is essential for forage production. However, excessive use of synthetic fertilizers causes environmental imbalances. An alternative to reduce these effects is to seek alternative fertilizers, such as wood ash produced from agro-industrial waste, when integrated with appropriate base saturation management. This study aims to compare the effects of fertilization with wood ash (WA), organomineral (OM), and mineral (M) fertilizers associated with different levels of base saturation on the growth and water productivity of Panicum maximum cv. BRS Zuri. The experiment was conducted in a greenhouse, using a randomized block design in a 3 × 3 factorial arrangement. The treatments consisted of three types of fertilization (WA, OM and M) and three levels of base saturation (0, 25%, and 50%). Leaf area, chlorophyll index, shoot dry mass and root dry mass, water consumption, and water productivity of Zuri grass were evaluated. The results showed significant increases in leaf area, with values of up to 4564.5 cm².pot⁻¹ and a chlorophyll index of up to 36.2 units. In addition, the dry mass of the aerial part reached up to 46.7 g.pot⁻¹, and the dry mass of the roots reached 21.7 g.pot⁻¹ with the use of OM fertilizers. These values represent an increase of between 43.1% and 69.6% compared to the values of conventional fertilizers. In addition, water productivity reached 4.9 g.L⁻¹ with WA-based fertilizers, an increase of around 39% compared to the values of mineral fertilizers.

Adubação mineral, orgânica e organomineral na cultura do rabanete / Mineral, organic and organomineral fertilization in rabanet culture