Two spinach (Spinacea oleracea L.) cultivars were evaluated for their response to deficient (0.25 mmol c L −1 or 0.25 K) and sufficient (5.0 mmol c L −1 or 5.0 K) potassium (K) levels combined with salinities of 5, 30, 60, 90, and 120 mmol c L −1 NaCl. Plants substituted K for Na proportionally with salinity within each K dose. Plants favored K + over Na + , regardless of salinity, accumulating significantly less Na at 5.0 K than at 0.25 K. Salinity had no effect on N, P, and K shoot accumulation, suggesting that spinach plants can maintain NPK homeostasis even at low soil K. Ca and Mg decreased with salinity, but plants showed no deficiency. There was no Na + to K + or Cl − to NO 3 − competition, and shoot biomass decrease was attributed to excessive NaCl accumulation. Overall, 'Raccoon' and 'Gazelle' biomasses were similar regardless of K dose but 'Raccoon' outproduced 'Gazelle' at 5.0 K at the two highest salinity levels, indicating that 'Raccoon' may outperform 'Gazelle' at higher NaCl concentrations. At low K, Na may be required by 'Raccoon', but not 'Gazelle'. This study suggested that spinach can be cultivated with recycled waters of moderate salinity, and less potassium than recommended, leading to savings on crop input and decreasing crop environmental footprint.

Information is scarce on the interaction of mineral deficiency and salinity. We evaluated two salt-tolerant spinach cultivars under potassium (K) doses (0.07, 0.15, 0.3, and 3.0 mmolc L−1) and saline irrigation (5, 30, 60, 120, and 160 mmolc L−1 NaCl) during germination and growth. There was no interaction between salinity and K. Salinity decreased germination percent (GP), not always significantly, and drastically reduced seedling biomass. ‘Raccoon’ significantly increased GP at 60 mmolc L−1 while ‘Gazelle’ maintained GP up to 60 or 120 mmolc L−1. After 50 days under saline irrigation, shoot biomass increased significantly at 30 and 60 mmolc L−1 at the lowest K dose but, in general, neither salinity nor K dose affected shoot biomass, suggesting that salinity supported plant growth at the most K-deficient dose. Salinity did not affect shoot N, P, or K but significantly reduced Ca, Mg, and S, although plants had no symptoms of salt toxicity or mineral deficiency. Although spinach seedlings are more sensitive to salt stress, plants adjusted to salinity with time. Potassium requirement for spinach growth was less than the current crop recommendation, allowing its cultivation with waters of moderate to high salinity without considerable reduction in yield, appearance, or mineral composition.

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RESUMO A cultura do taro (Colocasia esculenta L.), cultivar Japonês, é bastante interessante para o cultivo consorciado, porque apresenta ciclo longo e rusticidade, em relação a fatores ambientais e biológicos adversos. Objetivou-se, com este trabalho, avaliar a viabilidade agronômica e a rentabilidade econômica do consórcio taro e pepino. O experimento foi conduzido a campo, de outubro de 2012 a junho de 2013. Constou de sete tratamentos, sendo o pepino, em três deles, cultivado na forma de consórcio com o taro, com 1 planta a cada 30 cm; 2 plantas a cada 60 cm, opostas entre si e opostas alternadas entre si nas linhas. Outros três tratamentos consistiram em cultivo do pepino solteiro, seguindo a mesma distribuição do consorciado. Para o último tratamento, foi utilizado o taro solteiro. O delineamento experimental foi o de blocos casualizados, com quatro repetições. Foram determinados os parâmetros de fluorescência da clorofila, produtividade das culturas e indicadores econômicos. Os consórcios favoreceram a produção de pepino, mas afetaram a do taro. Todos os consórcios foram agronomicamente viáveis, por apresentarem uso eficiente da terra acima da unidade, além de renda bruta superior ao controle. Entretanto, por causa do baixo valor de mercado para o pepino, por ocasião da colheita, a renda líquida não diferiu da renda do monocultivo do taro. Os parâmetros da fluorescência da clorofila podem explicar, em parte, os menores valores de produção de rizomas de taro obtidos nos tratamentos em associação com pepino.

The aeroponic production of certified seed potatoes is a booming alternative for arid and semi-arid areas where fresh water is scarce and soil-borne diseases and nematodes preclude field production. Although widely used in aeroponics, nutrient-solution salinity effects have not been evaluated in potatoes. This study aimed to (1) establish the best of two nutrient solutions (Otazú vs. modified Furlani) at 20, 50, 100, and 150% of the crop-recommended dose for seed-potato production, (2) evaluate growth indexes to diagnose plant-N status, and (3) establish a prognosis for the yield of nuclear seed potatoes under aeroponics. At 21 days after transplanting, there was a significant correlation between the nitrate-N petiole-sap test and some of the parameters measured. The 4th leaf indexes correlated with yield parameters indicating that they can be used to prognosticate the final minituber yield. The best parameters to diagnose the N status in potato plants were: 4th leaf area, length, and dry weight (Otazú’s), SPAD, and 4th leaf area (modified Furlani’s). Although both nutrient solutions had similar nitrogen concentrations, Otazú’s nutrient solution at 100% of the recommended nitrogen dose had lower salinity than the modified Furlani’s solution and was the best to produce nuclear seed potatoes.