Características morfofisiológicas de plantas clonais de Passiflora alata crescidas em diferentes doses de nitrogênio e níveis de sombreamento

Pereira

et al. 2019

SCA

The poor chemical quality of water, especially in arid and semiarid regions, almost always precludes the practice of irrigated agriculture, thus demanding the adoption of techniques that mitigate the deleterious effects of excess salt on soil and plants. The aim of this research was to evaluate the effectiveness of nitrogen fertilization in mitigating the negative effects of excess salt in irrigation water on the growth of yellow passion fruit seedlings grown in a greenhouse in plastic tubes containing 0.65 dm3 of substrate. The treatments were organized in randomized blocks, in accordance with a 5 × 3 factorial scheme – five electrical conductivities of irrigation water (0.3, 1.0, 2.0, 3.0, and 4.0 dS m?1) combined with three levels of nitrogen fertilizer (no nitrogen fertilization and 150 mg dm?3 of N derived from either ammonium sulfate or urea). Evaluations were performed 80 days after sowing and consisted of measuring the seedling height, stem diameter, number of leaves, leaf area, leaf nitrogen content, leaf concentration of chlorophyll a and b and total chlorophyll, specific leaf area, leaf area ratio, and Dickson quality index. An increase in the electrical conductivity of irrigation water hindered the production of yellow passion fruit seedlings. Nitrogen fertilization, with urea or ammonium sulfate, mitigated the effects of irrigation water salinity and favored the growth and quality of yellow passion fruit seedlings. Yellow passion fruit seedlings with a minimum quality standard (DQI) can be produced with irrigation water with salinity of 1.8 dS m?1, which means they can be considered as moderately sensitive. The higher quality provided by nitrogen to the yellow passion fruit seedlings made them more tolerant to salinity, allowing the use of water with salinity of 2.1 and 2.5 dS m?1 under fertilization with ammonium sulfate and urea, respectively.

Section: Morphophysiological Indicessupporting

confidence: 70%

Section: Growth and Leaf Productionmentioning

confidence: 99%

Nitrogen as a mitigator of salt stress in yellow passion fruit seedlingss

Pereira

et al. 2019

SCA

“…This trend was also observed in Passiflora alata seedlings that obtained maximum photosynthetic values at low N doses (up to 146 mg kg −1 ) 176 d after staking [16]. It has been reported that tree plants exhibit increased N demand with increasing age and during fruit production [17], and two main sources of N that fruit trees use for their vegetative growth and reproduction are root N uptake and internal N cycling.…”

Section: Nitrogen Fertilization Increased Photosynthetic Rates Of Eugsupporting

confidence: 61%

Growth, Physiology and Nutrient Use Efficiency in Eugenia dysenterica DC under Varying Rates of Nitrogen and Phosphorus

Reis

Silva

Santana

et al. 2020

Plants

The production of high-quality seedlings and their use in commercial planting reduce pressure on natural areas. Eugenia dysenterica DC is a native fruit tree from the Brazilian Cerrado, whose nutritional requirements are still unclear. This study aimed to evaluate the effects of nitrogen (N) and phosphorus (P) supplementation on the physiology, growth and nutrient uptake, and use efficiencies of E. dysenterica seedlings grown in glasshouse conditions. The following rates were used in separate experiments: 0, 50, 100, 200, and 400 mg dm−3 N and 0, 100, 200, 400, and 600 mg dm−3 P. The experiment was conducted in a randomized block with four replications. The lowest N rate (50 mg dm−3) increased the stomatal conductance (gS) and, consequently, resulted in the highest transpiration (E), electron transport (ETR), and photosynthetic (A) rates. Also, rates of 50 mg dm−3 and 100 mg dm−3 N increased the Root Uptake Efficiency (RUE) and plant Nutrient Use Efficiency (NUE) for macronutrients and the RUE for micronutrients, stimulating plant growth. Phosphorous fertilization resulted in the maximum values for photosynthesis, electron transport rate, total dry mass, and NUE at the 200 mg dm−3 rate. The results of this study suggest that fertilization with 50 mg dm−3 N and 200 mg dm−3 P is suitable for the development of E. dysenterica seedlings.

“…The photosynthetic rate (A) increased up to a dose of 104.3% with a value of 15.51 µmol CO 2 m -2 s -1 ( Figure 2B). This result can be attributed to the fact that fertilization with these nutrients favors biosynthesis of photosynthetic components, such as the rubisco enzyme and chlorophyll molecules, inducing stomatal opening due to the greater demand for CO 2 (Freitas, Almeida, Lago, Souza, & Souza, 2012).…”

Section: Resultsmentioning

confidence: 99%

Morphophysiology of yellow passion fruit seedlings under application of nitrogen and potassium and irrigation with high-salinity water

Figueiredo

Nóbrega

Fátima

et al. 2020

Semina: Ciênc. Agrár.

Salinity is one of the most problematic abiotic stresses in agriculture globally, especially in semi-arid regions. Thus, the application of nutrients, such as nitrogen and potassium to improve plant nutritional conditions may be a viable alternative to minimize the negative effects of saline stress. Therefore, the aim of this study was to evaluate the morphophysiological behavior of yellow passion fruit seedlings under varying nitrogen and potassium doses and irrigation with salt water. The experimental design was a randomized complete block with a 5 x 5 incomplete factorial scheme, generated from the Central Composite Design with five electrical conductivities of irrigation water (0.5, 0.98, 2.15, 3.32, and 3. 80 dS m-1) and five increasing doses of nitrogen and potassium (0.0, 29.08, 100.0, 170.92, and 200.0%). Leaf, stem, and root dry phytomass and gas exchange were evaluated 75 days after sowing. The increase in salinity had negative effects on the morphological and physiological characteristics of yellow passion fruit seedlings. The application of nitrogen and potassium positively influenced photosynthetic rate and leaf and root dry phytomasses. The application of nitrogen and potassium increased intercellular CO2 concentration and transpiration in yellow passion fruit seedlings under saline stress.