Responses of Cynanchum taiwanianum and Its Bioactive Compound Biosynthesis to Levels of Nitrogen and Potassium Fertilization

Cynanchum taiwanianum is an important plant used in traditional medicine. The increasing demand and lack of information regarding its cultivation have become concerns for sustainability. This study examined the effects of nitrogen and potassium fertilization rates on the growth and biosynthesis of main bioactive compounds, including cynandione A and polyphenolic compounds, in field-cultivated C. taiwanianum. Two field experiments were conducted using three levels of nitrogen (N100, N150 and N200) and three levels of potassium (K100, K150 and K200) treatments. The experimental variables were either N or K fertilizer. The results showed that, aside from N200, N and K fertilization significantly increased C. taiwanianum shoot and tuber biomass. High N fertilization resulted in low total phenolic and total flavonoid contents in shoots and tubers, but the effects of K fertilization were minimal. Cynandione A, an important bioactive compound, was only detected in tubers; its content were enhanced with the increasing K fertilization, but reduced with excess N fertilization (N200). Although N and K fertilizers are important for C. taiwanianum tuber production, the yield of cynandione A was associated with K but not N fertilization rates. These results provide some essential information for the optimal production of C. taiwanianum tubers and functional compounds. Further studies are required to examine the mechanism(s) of cynandione A biosynthesis and its compartmentation in plant tissues.

Tuning Potassium Fertilization to Improve pH and Acidity in Glera Grapevine (Vitis vinifera L.) under a Warming Climate

Potassium concentration in grape berries can affect acidity and pH in must and wines. Under the current warming scenario, where preserving equilibrated value for these grape parameters is increasingly challenging, K fertilization could represent a tool to manage grape composition. In this study, the effect of potassium fertilization was investigated over 4 years (2013–2016) in field-grown grapevines (Vitis vinifera cv. Glera). Four different potassium rates (0, 15, 30, 60 kg K2O ha−1 year−1) were tested and agronomic responses, grape quality as well as K concentration in the berry were recorded over the four years. At harvest, yield parameters and total soluble solids were unaffected by potassium fertilization. On the contrary, the titratable acidity of the musts was increased by the higher rate of potassium (K60), and both tartaric and malic acids showed higher values when the K rate was higher. K fertilization did not affect the pH, as all the treatments displayed comparable pH values and in an optimal range for winemaking. Overall, in our experimental conditions, medium potassium inputs showed better results on Glera grape quality compared to low K rates, by promoting higher titratable acidity levels without altering the pH in musts.

Effects of Potassium Fertilization, Cultivar Specifics and Seedling Temperature Regime on Growth Parameters and Yield of Tomato (Solanum lycopersicum L.)

Background: Potassium fertilization shows beneficial effect on formation of tomato vegetative biomass and productivity. The purpose of this study was to determine the extent to which split potassium application and seedling temperature regime affects the growth parameters (leaf number, leaf area, fresh leaf weight and LAI) and yield of various tomato cultivars. Methods: A pot experiment was conducted to investigate the impact of single dose and split potassium fertilization treatments, cultivar specifics and seedling temperature regime on growth parameters and yield of tomato. Ten high yielding classic round shape tomato cultivars with determinate growth habitat were planted on Fluvisol. Single and split potassium fertilization treatments were tested. Result: The seedlings growth temperature regime and splitting the potassium fertilization treatment did not have a significant effect on the development of leaf biomass in tomato plants. Results revealed that leaf number, leaf area, fresh leaf weight and LAI of tomato plants was significantly affected by the cultivar genetic factor. Tomato yield were significantly affected by cultivars and split potassium fertilization treatments. Cultivars that measured the highest leaf area, fresh leaf weight and LAI and were also the highest yielding ones. A positive correlation between LAI and tomato fruit yield was observed.

Effect of nitrogen, phosphate and potassium fertilization on dystrophic soil on the content of secondary metabolites in Hydrocotyle umbellata L. var. bonariensis (Lam.) Spreng

The knowledge of medicinal plants is of great importance for popular health. On the other hand, the levels of secondary metabolites in medicinal plants is an important parameter to be evaluated. The study of the nutrition of plants and the production of metabolites can provide the identification of beneficial factors and also find out if there are harmful effects of this fertilization/nutrition. In this study, three experiments were carried out (nitrogen, phosphate and potassium fertilization) in the culture of Hydrocotyle umbellata L. var. bonariensis (Lam.) Spreng on dystrophic Red Latosol on metabolite production (total phenols, total flavonoids and hibalactone content). It was used the soil of a rural property in the municipality of Anápolis – Goiás (Brazil). The experimental design was completely randomized, in a controlled environment. The experiment involved the following dosages of fertilization: nitrogen (0; 30; 45; 60 e 75 kg of N.ha-1); phosphate (0; 120; 150; 180 e 210 kg of P2O5.ha-1) and potassium (0; 25; 50; 75 e 100 kg of K2O.ha-1). The maximum contents of total phenols were with the medium level of nitrogen, zero level of phosphorous and highest level of potassium. For the total flavonoid, the maximum contents were obtained with the medium levels of nitrogen and potassium and zero level of phosphorus. Finally, the hibalactone content was favored by highest level of nitrogen and zero levels of phosphorus and potassium.

Influence of Rainfall and Water Deficit in the Efficiency of Potassium Fertilizer on the Productivity of Oil Palm (Elaeis Guineensis Jacq.), Grown in Southeastern Côte d’Ivoire

In Côte d’Ivoire, palm oil occupies a preponderant position in agricultural production, in the economy, as well as consumer fats. Yield remains low, even with improved plant material being popularized whose productivity is estimated at more than 25 tons/ha/year. Trials have been set up in La Mé and Ehania (South-east Côte d’Ivoire), to help improve oil palm productivity, through a comparative study of the efficiency of potassium fertilization applied according to the locality. The experiments were conducted in Fisher blocks, including 5 treatments and 4 repetitions. The treatments included 5 doses of potassium fertilizer (T1, T2, T3, T4, T5) corresponding, respectively, to 1; 1.5; 2; 2.5; 3 kg KCl/tree/year. The results showed that the rainfall recorded in the locality of Ehania was significantly higher than that of La Mé. The average annual rainfall was 2000 mm of water in Ehania against, approximately, 1700 mm of water in La Mé. The yield and its components (weight of the bunch and number of bunches) were gradually improved according to the locality of cultivation by the different doses of fertilizer applied. This improvement was significantly higher on the Ehania plantation compared to that of La Mé. This improvement was approximately 30% and 27% compared to the standard dose of 1 kg KCl/tree/year, respectively, in Ehania and La Mé. It appears that the locality intervenes in the efficiency of potassium fertilizers, in the improvement of yield and its components. Rainfall appears, as, a main factor of productivity observed on the plot of the oil palm. Strict compliance with the choices of suitable areas, combined with reasoned potassium fertilization, will allow a better expression of the production potential of new oil palm plant material, currently being popularized.

Saline waters and nitrogen/potassium fertilization combinations on physiological aspects and production of West Indian cherry

This study evaluated the influence of combinations of nitrogen and potassium doses on the physiology and fruit production of West Indian cherry irrigated with waters of different salinities in the second year of cultivation. The experiment was conducted in the municipality of Pombal-PB, Brazil, in plastic containers adapted as lysimeters installed in the field, in a randomized block design, 5 x 4 factorial scheme corresponding to five levels of electrical conductivity of irrigation water (ECw): 0.3, 1.3, 2.3, 3.3 and 4.3 dS m-1, and four combinations of nitrogen and potassium fertilization: 70% N + 50% K2O; 100% N + 75% K2O; 130% N + 100% K2O and 160% N + 125% K2O of the dose recommended for West Indian cherry, with three replicates and one plant per plot. The cv. ‘Flor Branca’ was grafted on the cv. ‘Junco’, between 420 and 550 days after transplanting. Nitrogen and potassium combinations did not mitigate the deleterious effects of water salinity on the physiology and fruit formation of West Indian cherry. An increase in ECw intensifies the intercellular electrolyte leakage and reduces the water potential in the branch, chlorophyll content in the leaves, CO2 assimilation rate, equatorial and polar diameters as well as the mass of fruits. Fertilization of plants with 70% N + 50% of K2O, compared to the other fertilization combinations, causes less intercellular electrolyte leakage and promotes higher CO2 assimilation rates, higher chlorophyll content in leaves, and fruits of larger size and mass. Keywords: Malpighia emarginata D. C, mineral fertilization, salt stress.

Fruit quality of West Indian cherry under saline water irrigation and nitrogen-potassium fertilization

ABSTRACT The presence of waters with high salt concentration stands out as a limiting factor for the quality of agricultural production. Thus, this study aimed to evaluate the fruit quality of West Indian cherry cv. Flor Branca, subjected to irrigation with water of different salinity levels and combinations of nitrogen-potassium fertilization, between 630 and 750 days after transplanting in the field. A randomized block design was used in a 5 × 4 factorial arrangement, with three replicates, whose treatments consisted of five values of electrical conductivies of irrigation water - ECw (0.3, 1.3, 2.3, 3.3 and 4.3 dS m-1) and four combinations of nitrogen and potassium fertilization (70-50, 100-75, 130-100 and 160-125% of recommendation of N and K2O, respectively). Electrical conductivity of irrigation water above 0.3 dS m-1 reduces the polar and equatorial diameters, hydrogen potential and flavonoid concentration and increases titratable acidity in West Indian cherry fruits. N-K2O combination of 70/50% of fertilizer recommendation reduces the effect of salt stress of irrigation water on the anthocyanin concentration in the fruits at ECw of 1.3 dS m-1 and ascorbic acid at ECw of 3.3 and 4.3 dS m-1.