Nutrient Solution For Growth Research Articles

Selenium-Induced Toxicity Is Counteracted by Sulfur in Broccoli (Brassica oleracea L. var. italica).

Selenium (Se) is an essential micronutrient for humans. Increasing Se content in food crops offers an effective approach to enhance the consumption of Se in human diets. A thoroughly understanding of the effects of Se on plant growth is important for Se biofortification in food crops. Given that Se is an analog of sulfur (S) and can be toxic to plants, its effect on plant growth is expected to be greatly affected by S nutrition. However, this remains to be further understood. Here, we evaluated the influence of Se treatments on broccoli (Brassica oleracea L. var. italica) growth when S was withheld from the growth nutrient solution. We found that Se was highly toxic to plants when S nutrition was poor. In contrast to Se treatments with adequate S nutrition that slightly reduced broccoli growth, the same concentration of Se treatments without S supplementation dramatically reduced plant sizes. Higher Se toxicity was observed with selenate than selenite under low S nutrition. We examined the bases underlying the toxicity. We discovered that the high Se toxicity in low S nutrition was specifically associated with an increased ratio of Se in proteins verse total Se level, enhanced generation of reactive oxygen species, elevated lipid peroxidation causing increased cell membrane damage, and reduced antioxidant enzyme activities. Se toxicity could be counteracted with increased supplementation of S, which is likely through decreasing non-specific integration of Se into proteins and altering the redox system. The present study provides information for better understanding of Se toxicity and shows that adequate S nutrition is important to prevent Se toxicity during biofortification of crops by Se fertilization.

Effects of Photoperiod, Light Intensity and Electrical Conductivity on the Growth and Yield of Quinoa (Chenopodium quinoa Willd.) in a Closedtype Plant Factory System

Quinoa (Chenopodium quinoa Willd.) is a plant native to the Andean region that has become increasing popular as a food source due to its high nutritional content. This study determined the optimal photoperiod, light intensity, and electrical conductivity (EC) of the nutrient solution for growth and yield of quinoa in a closed-type plant factory system. The photoperiod effects were first analyzed in a growth chamber using three different light cycles, 8/16, 14/10, and 16/8 hours (day/night). Further studies, performed in a closed-type plant factory system, evaluated nutrient solutions with EC (salinity) levels of 1.0, 2.0 or 3.0 dS·m -1 . These experiments were assayed with two light intensities (120 and 143 μ㏖·m -2 ·s -1 ) under a 12/12 and 14/10 hours (day/night) photoperiod. The plants grown under the 16/8 hours photoperiod did not flower, suggesting that a long-day photoperiod delays flowering and that quinoa is a short-day plant. Under a 12/12 h photoperiod, the best shoot yield (both fresh and dry weights) was observed at an EC of 2.0 dS·m -1 and a photosynthetic photon flux density (PPFD) of 120 μ㏖·m -2 ·s -1 . With a 14/10 hphotoperiod, the shoot yield (both fresh and dry weights), plant height, leaf area, and light use efficiency were higher when grown with an EC of 2.0 dS·m -1 and a PPFD of 143 μ㏖·m -2 ·s -1 . Overall, the optimal conditions for producing quinoa as a leafy vegetable, in a closed–type plant factory system, were a 16/8 h (day/night) photoperiod with an EC of 2.0 dS·m -1 and a PPFD of 143 μmol·m -2 ·s -1 .

K+ starvation causes a differential effect on shoot and root K+ (Rb+) uptake in sunflower plants

Sunflower plants (Helianthus annuus L. cv Sun-Gro) with different K+ nutritional status were used to study the effect of K+ starvation on shoot and root Rb+ uptake as well as its distribution in the plant. The plants were grown in hydroponic medium during 21d. At the end of this period, Rb+ treatments were applied either to shoot or root. In one set of plants, an aqueous solution of RbCl was sprayed uniformly on shoot, while in another set, K+ from the growth nutrient solution was replaced by Rb+. The results obtained in this study indicate that K+ starvation affects differently to Rb+ uptake by shoot and roots. The root's Rb+ uptake, as it was expected, was higher in those plants with low internal content than in plants with adequate levels of K+. Conversely, K+ starvation inhibited the uptake of Rb+ by the shoot. In addition, the results showed that K+ starvation favored the accumulation of Rb+ from foliar treatment in both root and growing parts of the shoot whereas inhibited its accumulation on totally expanded leaves. These results suggest that K+ foliar treatments become less efficient in improving K+ concentration in leaves when plants are under serve K+ deprivation conditions.