scholarly journals Fruit Yield, Size, and Color Responses of Two Greenhouse Cucumber Types to Nitrogen Fertilization in Perlite Soilless Culture

2005 ◽  
Vol 15 (3) ◽  
pp. 565-571 ◽  
Author(s):  
C. Jasso-Chaverria ◽  
G.J. Hochmuth ◽  
R.C. Hochmuth ◽  
S.A. Sargent
Keyword(s):  
Nutrient Solution ◽  
Fruit Production ◽  
N Fertilization ◽  
N Concentration ◽  
Hue Angle ◽  
Greenhouse Cucumber ◽  
Leaf N Concentration ◽  
Black Plastic ◽  
Spring Harvest ◽  
Leaf N

Two greenhouse cucumber (Cucumis sativus) cultivars with differing fruit types [European (`Bologna') and Beit-alpha (`Sarig')] were grown during two seasons in a perlite medium in black plastic nursery containers in a passively ventilated greenhouse in northern Florida to evaluate fruiting responses to nitrogen (N) fertilization over the range of 75 to 375 mg·L–1. Fruit production, consisting mostly of fancy fruits, increased quadratically with N concentration in the nutrient solution, leveling off above 225 mg·L–1 for both cucumber cultivars. Fruit length and diameter were not affected by N concentration in the nutrient solution. Leaf N concentration, averaged over three sampling dates, increased linearly with N concentration in the nutrient solution from 46 g·kg–1 with 75 mg·L–1 N to 50 g·kg–1 with 375 mg·L–1 N. Fruit firmness decreased with increasing N concentration and there was little difference in firmness between the two cultivars. Firmness was similar across three measurement dates during the spring harvest season, but increased during the season in the fall. Fruit color responses to N concentration were dependent on the specific combination of experiment, sampling date, and cultivar. For most combinations of experiment, sampling date, and cultivar, cucumber epidermal color was greener (higher hue angle) with increased N concentration. The color was darkest (lowest L* value) and most intense (highest chroma value) with intermediate to higher N concentrations.

scholarly journals Effect of N fertilization rate on soil alkali-hydrolyzable N, subtending leaf N concentration, fiber yield, and quality of cotton

2016 ◽  
Vol 4 (4) ◽  
pp. 323-330 ◽  
Author(s):  
Binglin Chen ◽  
Hongkun Yang ◽  
Weichao Song ◽  
Chunyu Liu ◽  
Jiao Xu ◽  
...  
Keyword(s):  
Fertilization Rate ◽  
N Fertilization ◽  
Yield And Quality ◽  
Fiber Yield ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Leaf N

scholarly journals Down-Regulation of Photosynthesis to Elevated CO2 and N Fertilization in Understory Fraxinus rhynchophylla Seedlings

Forests ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1197
Author(s):  
Siyeon Byeon ◽  
Kunhyo Kim ◽  
Jeonghyun Hong ◽  
Seohyun Kim ◽  
Sukyung Kim ◽  
...  
Keyword(s):  
Elevated Co2 ◽  
N Fertilization ◽  
Leaf Nitrogen ◽  
N Availability ◽  
Down Regulation ◽  
Leaf Production ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Regulation Of Photosynthesis ◽  
Leaf N

(1) Background: Down-regulation of photosynthesis has been commonly reported in elevated CO2 (eCO2) experiments and is accompanied by a reduction of leaf nitrogen (N) concentration. Decreased N concentrations in plant tissues under eCO2 can be attributed to an increase in nonstructural carbohydrate (NSC) and are possibly related to N availability. (2) Methods: To examine whether the reduction of leaf N concentration under eCO2 is related to N availability, we investigated understory Fraxinus rhynchophylla seedlings grown under three different CO2 conditions (ambient, 400 ppm [aCO2]; ambient × 1.4, 560 ppm [eCO21.4]; and ambient × 1.8, 720 ppm [eCO21.8]) and three different N concentrations for 2 years. (3) Results: Leaf and stem biomass did not change under eCO2 conditions, whereas leaf production and stem and branch biomass were increased by N fertilization. Unlike biomass, the light-saturated photosynthetic rate and photosynthetic N-use efficiency (PNUE) increased under eCO2 conditions. However, leaf N, Rubisco, and chlorophyll decreased under eCO2 conditions in both N-fertilized and unfertilized treatments. Contrary to the previous studies, leaf NSC decreased under eCO2 conditions. Unlike leaf N concentration, N concentration of the stem under eCO2 conditions was higher than that under ambient CO2 (4). Conclusions: Leaf N concentration was not reduced by NSC under eCO2 conditions in the understory, and unlike other organs, leaf N concentration might be reduced due to increased PNUE.

scholarly journals (328) Effect of Supplemental Nitrogen Applicationat Selected Times on Pecan

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1065D-1065
Author(s):  
Michael Smith
Keyword(s):  
N Fertilization ◽  
The Other ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Leaf N

Supplemental nitrogen applications were tested to reduce irregular bearing and improve yield on drip-irrigated pecan (Caryaillinoinensis Wangenh. C. Koch. cv. Mohawk) trees planted in 1989. Treatments were: 1) no N fertilization; 2) 75 kg·ha-1 N in March; 3) 75 kg·ha-1 N in March plus 50 kg·ha-1 N in August; and 4) 75 kg·ha-1 N in March plus 50 kg·ha-1 N in October. Withholding N did not reduce July leaf N concentration compared to the other treatments until the sixth year of the study. Trees receiving N had similar July leaf N concentrations regardless of treatment throughout the study. October leaf N concentrations were unaffected by treatment, except in 2002, when withholding N suppressed leaf N compared to other treatments. The percentage of fruiting shoots was lower when supplemental N was applied in October compared to August during 2 of 6 years. Otherwise, the percentage of fruiting shoots was unaffected by treatment. Weight per nut and kernel percentage were not affected by treatment, except kernel percentage was lower during 1 year when supplemental N was applied in August compared to October. Kernel grade was usually not affected by treatment.

scholarly journals Fertilization and Growth of Field-grown Citrus Nursery Trees in Florida

2008 ◽  
Vol 18 (1) ◽  
pp. 29-33 ◽  
Author(s):  
Frederick S. Davies ◽  
Glenn Zalman
Keyword(s):  
Dry Weight ◽  
Fine Sand ◽  
N Fertilization ◽  
Poncirus Trifoliata ◽  
Tree Trunk ◽  
Trunk Diameter ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Optimum N Rate ◽  
Leaf N

The objective of this study was to determine the effects of various levels of nitrogen (N) on growth of ‘Hamlin’ orange (Citrus sinensis) trees on Carrizo citrange (C. sinensis × Poncirus trifoliata) rootstock in a field nursery. Newly budded liners were obtained from commercial nurseries and received from 0 to 3976 kg N per treated hectare annually (8N–0P–6.6K) in 14 applications per season. Tree trunk diameter, height, and dry weight were measured in two separate experiments. Total dry weight and trunk diameter were greatest for trees receiving 794 kg·ha−1 N annually during both seasons. However, annual N rates more than 1589 kg·ha−1 reduced trunk diameters and dry weight compared with the optimum N rate during both seasons. Leaf N concentration and N rate were positively correlated in both seasons, but leaf N concentration was poorly correlated with tree trunk diameter and dry weight. Therefore, very high rates of N fertilization may actually reduce ‘Hamlin’ orange tree growth in field nurseries when growing in an Arredondo fine sand.

scholarly journals Optimal Nitrogen Concentration and Rapid Nutritional Diagnosis of Nitrogen Requirement for Container Production of Malabar Chestnut

2015 ◽  
Vol 25 (5) ◽  
pp. 602-607
Author(s):  
Yung-Liang Peng ◽  
Fang-Yin Liu ◽  
Rong-Show Shen ◽  
Yu-Sen Chang
Keyword(s):  
Plant Growth ◽  
Dry Weight ◽  
N Fertilization ◽  
Chlorophyll Meter ◽  
Leaf Chlorophyll ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Leaf Dry Weight ◽  
N Requirement ◽  
Leaf N

Nitrogen (N) is a major element required for crop cultivation and an important factor affecting plant growth and development. Malabar chestnut (Pachira macrocarpa) is an important ornamental potted plant crop whose N requirement has been studied, and a rapid monitoring method to manage N fertilization during its commercial production is yet to be established. Malabar chestnut seedlings were fertilized weekly with 0, 4, 8, 16, or 24 mm N. After 12 weeks, 16 mm N was found to yield the greatest plant growth such as plant height, number of nodes, and total leaf area. Measurements of chlorophyll meter readings, leaf chlorophyll concentration, leaf N concentration, and leaf dry weight all indicated that the optimal level of N fertilization was 16 mm N. A chlorophyll meter can be used to monitor nondestructively whether sufficient N has been supplied to support optimal plant growth. In this study, a chlorophyll meter reading of 46.1 corresponded with a critical leaf N concentration of 2.65%, defined as the leaf N concentration when the leaf dry weight was at 90% of saturation point. Additional N supplied beyond this critical level increased foliar chlorophyll content and improved the rate of net photosynthesis. Therefore, chlorophyll meter readings, which are convenient and nondestructive can serve as a reliable reference for commercial production in monitoring N requirement for optimum growth of malabar chestnut. Weekly fertilization of malabar chestnut with 16 mm N and maintaining leaf chlorophyll meter readings between 46.1 and 58.4 are recommended.

scholarly journals Nitrogen use efficiency and critical leaf N concentration of Aloe vera in urea and diammonium phosphate amended soil

Heliyon ◽  
2020 ◽  
Vol 6 (12) ◽  
pp. e05718
Author(s):  
Md. Akhter Hossain Chowdhury ◽  
Taslima Sultana ◽  
Md. Arifur Rahman ◽  
Tanzin Chowdhury ◽  
Christian Ebere Enyoh ◽  
...  
Keyword(s):  
Nitrogen Use Efficiency ◽  
Aloe Vera ◽  
Diammonium Phosphate ◽  
Nitrogen Use ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Use Efficiency ◽  
Leaf N ◽  
Amended Soil

Optical sensing estimation of leaf nitrogen concentration in maize across a range of water-stress levels

2011 ◽  
Vol 62 (6) ◽  
pp. 474 ◽  
Author(s):  
Tong-Chao Wang ◽  
B. L. Ma ◽  
You-Cai Xiong ◽  
M. Farrukh Saleem ◽  
Feng-Min Li
Keyword(s):  
Water Stress ◽  
Vegetation Index ◽  
Optical Sensing ◽  
Leaf Nitrogen ◽  
Growth Stages ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Chlorophyll Index ◽  
Plant Moisture ◽  
Leaf N

Optical sensing techniques offer an instant estimation of leaf nitrogen (N) concentration during the crop growing season. Differences in plant-moisture status, however, can obscure the detection of differences in N levels. This study presents a vegetation index that robustly measures differences in foliar N levels across a range of plant moisture levels. A controlled glasshouse study with maize (Zea mays L.) subjected to both water and N regimes was conducted in Ottawa, Canada. The purpose of the study was to identify spectral waveband(s), or indices derived from different wavebands, such as the normalised difference vegetation index (NDVI), that are capable of detecting variations in leaf N concentration in response to different water and N stresses. The experimental design includes three N rates and three water regimes in a factorial arrangement. Leaf chlorophyll content and spectral reflectance (400–1075 nm) were measured on the uppermost fully expanded leaves at the V6, V9 and V12 growth stages (6th, 9th and 12th leaves fully expanded). N concentrations of the same leaves were determined using destructive sampling. A quantitative relationship between leaf N concentration and the normalised chlorophyll index (normalised to well fertilised and well irrigated plants) was established. Leaf N concentration was also a linear function (R2 = 0.9, P < 0.01) of reflectance index (NDVI550, 760) at the V9 and V12 growth stages. Chlorophyll index increased with N nutrition, but decreased with water stress. Leaf reflectance at wavebands of 550 ± 5 nm and 760 ± 5 nm were able to separate water- and N-stressed plants from normal growing plants with sufficient water and N supply. Our results suggest that NDVI550, 760 and normalised chlorophyll index hold promise for the assessment of leaf N concentration at the leaf level of both normal and water-stressed maize plants.

scholarly journals Estimating Plant Nitrogen Concentration of Maize Using a Leaf Fluorescence Sensor across Growth Stages

2020 ◽  
Vol 12 (7) ◽  
pp. 1139
Author(s):  
Rui Dong ◽  
Yuxin Miao ◽  
Xinbing Wang ◽  
Zhichao Chen ◽  
Fei Yuan ◽  
...  
Keyword(s):  
Precision Agriculture ◽  
Fluorescence Sensor ◽  
Accurate Estimation ◽  
Growth Stages ◽  
Fluorescence Sensors ◽  
N Application ◽  
N Concentration ◽  
Leaf N Concentration ◽  
N Status ◽  
Leaf N

Nitrogen (N) is one of the most essential nutrients that can significantly affect crop grain yield and quality. The implementation of proximal and remote sensing technologies in precision agriculture has provided new opportunities for non-destructive and real-time diagnosis of crop N status and precision N management. Notably, leaf fluorescence sensors have shown high potential in the accurate estimation of plant N status. However, most studies using leaf fluorescence sensors have mainly focused on the estimation of leaf N concentration (LNC) rather than plant N concentration (PNC). The objectives of this study were to (1) determine the relationship of maize (Zea mays L.) LNC and PNC, (2) evaluate the main factors influencing the variations of leaf fluorescence sensor parameters, and (3) establish a general model to estimate PNC directly across growth stages. A leaf fluorescence sensor, Dualex 4, was used to test maize leaves with three different positions across four growth stages in two fields with different soil types, planting densities, and N application rates in Northeast China in 2016 and 2017. The results indicated that the total leaf N concentration (TLNC) and PNC had a strong correlation (R2 = 0.91 to 0.98) with the single leaf N concentration (SLNC). The TLNC and PNC were affected by maize growth stage and N application rate but not the soil type. When used in combination with the days after sowing (DAS) parameter, modified Dualex 4 indices showed strong relationships with TLNC and PNC across growth stages. Both modified chlorophyll concentration (mChl) and modified N balance index (mNBI) were reliable predictors of PNC. Good results could be achieved by using information obtained only from the newly fully expanded leaves before the tasseling stage (VT) and the leaves above panicle at the VT stage to estimate PNC. It is concluded that when used together with DAS, the leaf fluorescence sensor (Dualex 4) can be used to reliably estimate maize PNC across growth stages.

Nitrogen and Water Uptake on Sloping Lands of Thailand

2011 ◽  
Vol 356-360 ◽  
pp. 2484-2496
Author(s):  
Sireetorn Siriwong ◽  
Thanuchai Kongkaew ◽  
Georg Cadisch ◽  
Thomas Hilger
Keyword(s):  
Spatial Variability ◽  
Driving Force ◽  
N Fertilization ◽  
Control Measures ◽  
Yield Response ◽  
Maize Leaf ◽  
Mountainous Regions ◽  
N Concentration ◽  
Sloping Lands ◽  
Leaf N Concentration

Cultivation in the tropical mountainous regions by using hedgerow systems as erosion control measures is recommended due to its effectiveness in reducing soil erosion and in supplying N. However, competition for nutrients and water between crops and hedges reduces crop performance and yield response.13C stable isotope signature in combination with data on N and water availability and uptake in soil and plants framework was used to assess whether N or water function as a main driving force for spatial variability of crop yield along the alleys. The leaf δ13C values of maize were significantly (p<0.05) less depleted close to the hedges, suggesting that water stress was not the main driving force for spatial variability along the alleys. In the opposite, significant (p<0.05) N concentration depleted in maize leaf of plot with L. Leucocephala hedges, in particular at the row closed to hedgerow, in combination with significant (p<0.05) increase in δ13C values of leaf of the corresponding plot indicating the influence of N stress on poor maize performance and yield decrease. In addition, the significant (p<0.05) negative correlation between leaf δ13C values of maize, leaf N concentration and yield confirmed that N plays as a major role in crop decline towards hedgerows. Therefore, increasing amount of N fertilization to cropped area close to the hedgerows should be recommended for farmers, in order to encourage the acceptance of hedges system in tropical mountainous regions.

Rootstock influences postharvest anthracnose development in 'Hass' avocado

2001 ◽  
Vol 52 (10) ◽  
pp. 1017 ◽  
Author(s):  
S. L. Willingham ◽  
K. G. Pegg ◽  
A. W. Cooke ◽  
L. M. Coates ◽  
P. W. B. Langdon ◽  
...  
Keyword(s):  
First Record ◽  
Mineral Nutrients ◽  
Fruit Flesh ◽  
N Concentration ◽  
Nursery Stock ◽  
Leaf N Concentration ◽  
Hass Avocado ◽  
Mn Concentration ◽  
Leaf N

Rootstock studies conducted on ‘Hass’ avocado found that rootstock had a significant impact on postharvest anthracnose susceptibility. This is the first record of such an effect for avocado. The severity and incidence of anthracnose was significantly lower on ‘Hass’ grafted to ‘Velvick’ Guatemalan seedling rootstock compared with the ‘Duke 6’ Mexican seedling rootstock. Differences in anthracnose susceptibility were related to significant differences in concentrations of antifungal dienes in the leaves and mineral nutrients in the leaves and fruits from trees grafted to different rootstocks. Leaf diene concentrations were up to 1.5 times higher in ‘Hass’ trees on the ‘Velvick’ than the ‘Duke 6’ rootstock. In ungrafted nursery stock trees, diene concentrations were around 3 times higher in ‘Velvick’ than ‘Duke 6’ leaves. The ‘Velvick’/‘Hass’ combination also had a significantly lower leaf N concentration, a significantly higher fruit flesh Mn concentration, and significantly lower and higher leaf N/Ca and Ca+Mg/K ratios, respectively. A significant correlation (r = 0.82) between anthracnose severity and skin N/Ca ratio was also evident.

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