Abstract The substrate used in seedling production plays a major role in the initial plant development. In this sense, the objective was to evaluate the emergence capacity and establishment of basil seedlings in different proportions of alternative substrates based on charred rice husk and commercial substrate S10®. The experiment was carried out in expanded polyethylene trays, using basil seeds (Horticeres seeds®), which lasted 28 days. The experimental design was completely randomized, with five treatments (T1: 100 % commercial substrate (BCS); T2: 80 % BCS + 20 % Charred rice husk (CRH); T3: 60 % BCS + 40 % CRH; T4: 40 % BCS + 60 % CRH; T5: 20 % BCS + 80 % CRH) and three repetitions. Were evaluated leaf number, shoot length, root length, root dry mass, shoot dry mass, leaf area, germination, germination speed index, substrate physical analysis (density (dry and wet)), total porosity and aeration space, and chemical analysis (hydrogen potential (PH), and electrical conductivity (EC)). It was observed in the results that the substrate type interferes in the development and quality of the basil seedling. In the shoot lenght parameter, the treatment with 40 % BCS + 60 % CRH (T4) had a significant difference compared to the other treatments. Among the substrates, the best seedling performance was observed in the substrate with 80 % BCS + 20 % CRH (T2), which provided better seedling quality in relation to the other treatments.

Resumen El sustrato utilizado en la producción de plántulas juega un papel importante en el desarrollo inicial de la planta. En este sentido, el objetivo fue evaluar la capacidad de emergencia y el establecimiento de plántulas de albahaca en diferentes proporciones de sustratos alternativos basados en cáscara de arroz carbonizada y sustrato comercial S10®. El experimento se realizó en bandejas de polietileno expandido, utilizando semillas de albahaca (Horticeres seeds®), durante 28 días. El diseño experimental fue completamente al azar, con cinco tratamientos (T1: sustrato comercial 100 % (BCS); T2: 80 % BCS + 20 % cáscara de arroz carbonizada (CRH); T3: 60 % BCS + 40 % CRH; T4: 40 % BCS + 60 % CRH; T5: 20 % BCS + 80 % CRH) y tres repeticiones. Se evaluaron el número de hojas; la longitud del brote; la longitud de la raíz; la masa seca de la raíz; la masa seca del brote; el área de la hoja; la germinación; el índice de velocidad de germinación; el análisis físico del sustrato (densidad (seco y húmedo)); la porosidad total y el espacio de aireación; y análisis químico (potencial de hidrógeno (PH) y conductividad eléctrica (CE)). En los resultados se observó que el tipo de sustrato interfiere en el desarrollo y la calidad de las plántulas de albahaca. En el parámetro de longitud de yema, el tratamiento con 40 % BCS + 60 % CRH (T4) mostró una diferencia significativa con respecto a los otros tratamientos. Entre los sustratos, se observó el mejor rendimiento de plántulas en el sustrato con 80 % de BCS + 20 % de CRH (T2), lo que proporcionó una mejor calidad de plántulas en relación con los otros tratamientos.

ABSTRACT Potato cultivation is widespread around the world, being exposed to several abiotic stresses, including soils with high aluminum (Al) availability. Silicon (Si) is recognized for alleviating the stress caused by Al in various plant species. Thus, the aim of this study was to investigate the potential of Si to mitigate the oxidative stress caused by Al in potato genotypes, exhibiting differential sensitivity toward this element. Plants of the Al-sensitive genotype (SMIJ319-7) and Al-tolerant genotype (SMIF212-3) were grown for two weeks in a hydroponic system with the nutrient solution containing combinations of Al (0 and 1.85 mM) and Si (0, 0.5 and 1.0 mM). At the end of the experiment, photosynthetic parameters, pigment content, root and shoot growth, superoxide dismutase and guaiacol peroxidase activity and lipid peroxidation were evaluated. In both potato genotypes Al inhibited root and shoot growth and decreased all photosynthetic parameters and superoxide dismutase activity. Silicon was able to partially alleviate the damage caused by Al in parameters of root growth in the Al-tolerant genotype while increasing the activity of antioxidant enzymes and mitigating the Al-induced damage to membrane lipids in roots and shoot in both genotypes. The Al-tolerant genotype showed greater water use efficiency and transpiration rate in control conditions as compared to the Al-sensitive genotype. These data indicate that Si application can improve the defense ability of the tested potato genotypes against Al toxicity and that the Al-tolerant genotype is more responsive to Si.

RESUMO: O alumínio (Al) é altamente tóxico para as plantas, causando estresse e inibindo o crescimento e o silício (Si) é considerado benéfico para as plantas. Este elemento químico tem uma alta afinidade com o Al. O objetivo deste estudo foi investigar o potencial do Si em amenizar os efeitos tóxicos do Al sobre plantas de batata ( Solanum tuberosum L.) e avaliar se esse comportamento é diferente entre os genótipos com diferente sensibilidade ao Al. Plantas de batata dos genótipos SMIJ319-7 (sensível ao Al) e SMIF212-3 (tolerante ao Al) foram cultivadas por 14 dias em solução nutritiva (sem P e pH 4,5±0,1), sob exposição a combinações de Al (0 e 1,85mM) e Si (0; 0,5 e 1,0mM). Após esse período, parte aérea e raízes dos dois genótipos foram coletadas para determinar o conteúdo de Al nos tecidos e avaliar parâmetros morfológicos das raízes e parte aérea. Raízes de ambos os genótipos acumularam mais Al do que a parte aérea, e o genótipo tolerante ao Al acumulou mais Al do que o sensível, tanto nas raízes quanto na parte aérea. Além disso, a presença de 0,5 e 1,0mM de Si juntamente com Al reduziu o conteúdo de Al na parte aérea em ambos os genótipos e nas raízes do genótipo tolerante ao Al, respectivamente. O Si amenizou os efeitos tóxicos do Al para número de ramificações de raízes e de folhas em ambos os genótipos de batata. Si tem o potencial para amenizar os efeitos tóxicos do Al em plantas de batata, independente da sensibilidade ao Al.

ABSTRACT: Aluminum (Al) is highly toxic to plants, causing stress and inhibiting growth and silicon (Si) is considered beneficial for plants. This chemical element has a high affinity with Al. The aim of this study was to investigate the potential of Si to mitigate the toxic effects of Al on potato ( Solanum tuberosum L.) plants and assess whether this behavior is different among genotypes with differing degrees of sensitivity to Al. Potato plants of the genotypes SMIJ319-7 (Al-sensitive) and SMIF212-3 (Al-tolerant) were grown for fourteen days in nutrient solution (without P and pH 4.5±0.1) under exposure to combinations of Al (0 and 1.85mM) and Si (0, 0.5 and 1.0mM). After this period, shoot and roots of the two genotypes were collected to determine Al content in tissues and assess morphological parameters of root and shoot growth. Roots of both genotypes accumulated more Al than shoots and the Al-tolerant genotype accumulated more Al than the sensitive one, both in roots and in shoot. Furthermore, the presence of 0.5 and 1.0mM Si together with Al reduced the Al content in shoot in both genotypes and in roots of the Al-tolerant genotype, respectively. Si ameliorated the toxic effects of Al with regard to number of root branches and leaf number in both potato genotypes. Si has the potential to mitigate the toxic effects of Al in potato plants regardless of Al sensitivity.