Resumo O desenvolvimento de plantas mais eficientes no uso de nutrientes será fundamental para a agricultura nos próximos anos. O objetivo deste trabalho foi definir um marcador fisiológico do status nutricional do P para clones de batata cultivados fora do solo e in vitro, visando facilitar o processo de seleção de clones mais eficientes no uso de P. Para tanto, foram realizados dois experimentos com sete clones de batata (SMIC 148-A, Dakota Rose, SMINIA 793101-3, SMIB 106-7, SMIF 212-3, SMIJ 319-1 e P 150) cultivados em dois níveis de P (baixo e alto) no sistema de cultivo in vitro (1,935 e 19,346mg P L-1) e no cultivo fora do solo (2,32 e 23,2mg P L-1) usando areia como substrato. O teor de P inorgânico e a acumulação total de P na parte aérea e nas raízes parecem ser bons indicadores da condição nutricional de P em plantas de batata, tanto no cultivo fora do solo quanto no in vitro. A atividade das enzimas fosfatases ácidas (APases) nos tecidos da batata depende muito do sistema de cultivo, do clone e do órgão da planta analisado, dificultando a escolha deste como um marcador fisiológico para restrição de P em batata. A massa seca da planta de batata pode ser um bom indicador do status nutricional do P em clones cultivados fora do solo.

Abstract The development of more efficient plants in the use of nutrients will be fundamental for agriculture in the coming years. The objective of this work was to define a physiological marker of the nutritional status of P for potato clones cultivated soilless and in vitro, in order to facilitate the selection process of more efficient clones in the use of P. For this, two experiments were carried out with seven potato clones (SMIC 148-A, Dakota Rose, SMINIA 793101-3, SMIB 106-7, SMIF 212-3, SMIJ 319-1 and P 150) grown at two levels of P (low and high) in the culture systems in vitro (1.935 and 19.346mg P L-1) and in soilless (2.32 and 23.2mg P L-1) using sand as substrate. The inorganic P content and the total accumulation of P in shoot and roots seem to be good indicators of the nutritional status of P in potato plants, both in soilless and in vitro cultivation. The activity of the acidic phosphatase enzymes (APases) in the tissues of the potato depends very much on the culture system, the clone and the organ of the analyzed plant, making it difficult to choose it as a physiological marker for restriction of P in potatoes. The dry mass of the potato plant may be a good indicator of the nutritional status of P in clones grown soilless.

ABSTRACT The residue of imidazolinone herbicides in soil can be detrimental to soybean cultivation in rotation with Clearfield® rice. Thus, this research aimed to evaluate the ryegrass phytoremediation capacity on the imazapyr+imazapic residue in the soil in two soil moisture conditions in the off-season, and the effect on soybean growth in the next growing season. Two experiments were conducted between 2016 and 2017 in Santa Maria, Rio Grande do Sul state, Brazil. It was used the randomized block design in a 3 × 2 factorial. The first factor being the residue in the soil of 0, 210 and 420 g c.p.·ha–1 of the formulated mixture of the herbicides imazapyr+imazapic(525 + 175 g a.i.·kg–1) applied to rice in the 2015/2016 growing season, and the second factor being the presence or absence of ryegrass in the off-season. One experiment was conducted under soil moisture above 70% of field capacity in the off-season, and the other under ambient condition of soil moisture. The soil residue of the application of 420 g c.p.·ha–1 of the imazapyr+imazapic herbicides performed129 days before planting caused phytotoxicity and reduced dry matter of ryegrass under high soil moisture condition in the off-season in irrigated rice areas. Soybean, when planted 359 days after application, has its initial root and shoot growth affected by the residue of 210 and 420 g c.p.·ha–1 rates in high soil moisture condition in the off-season, regardless of ryegrass cultivation during the same period. However, grain yield is not affected.

Devido, principalmente, às ações antropogênicas, tais como industrialização e uso de insumos na agricultura, os níveis de cádmio têm aumentado em muitos solos agrícolas. O presente trabalho objetivou caracterizar o efeito desse metal no crescimento in vitro de duas cultivares de batata, 'Asterix' e 'Macaca'. Segmentos nodais de plantas previamente estabelecidas in vitro foram submetidos a doses de cádmio de 0 (controle), 100, 200, 300, 400 e 500µM em meio de cultivo MS. Avaliou-se o número de raízes aos 15 dias após a inoculação (DAI) dos explantes, o comprimento das raízes e da parte aérea, o número de segmentos nodais e de folhas e a matéria fresca e seca das raízes e da parte aérea aos 22DAI. O cádmio afetou negativamente o crescimento das duas cultivares de batata, demonstrando que ambas são sensíveis a esse metal.

Levels of cadmium have been increasing in many agricultural soils mainly due to the anthropogenic actions, such as industrialization and use of inputs in the agriculture. The present research aimed at characterizing the effect of this metal on in vitro growth of two potato cultivars, 'Asterix' and 'Macaca'. Nodal segments of plants previously in vitro established were submitted to cadmium concentration of 0 (control), 100, 200, 300, 400 and 500µM in MS. Number of roots was evaluated at 15 days after inoculation (DAI) of the explants, and root and shoot length, number of nodal segments and leaves, and fresh and dry mass of roots and shoot were evaluated at 22DAI. Cadmium negatively affected the growth of the two potato cultivars, demonstrating that both are sensible to this metal.