Nitrogen accumulation and partitioning in shoots of cotton plants infested with two-spotted spider mites

1997 ◽  
Vol 48 (4) ◽  
pp. 525 ◽  
Author(s):  
V. O. Sadras ◽  
L. J. Wilson
Keyword(s):  
Nitrogen Concentration ◽  
Reproductive Organs ◽  
Spider Mites ◽  
Leaf Nitrogen ◽  
Rapid Decline ◽  
Nitrogen Accumulation ◽  
Reproductive Growth ◽  
Large Reservoir ◽  
Main Site ◽  
Allometric Analysis

In cotton (Gossypium hirsutum L.), leaves are the main site of nitrogen reduction and constitute a large reservoir of organic nitrogen. Foliar herbivores, therefore, are likely to have detrimental effects on the nitrogen economy of the plant. A field experiment was conducted to investigate the effects of two-spotted spider mites (Tetranychus urticae Koch) on the accumulation and partitioning of nitrogen in cotton shoots. Control plants and plants infested with mites 3 times in the growing season were compared. Once established, mite colonies grew exponentially. After peaking at 35–64 mites/leaf, mite numbers declined sharply. Mites markedly affected both shoot nitrogen accumulation and partitioning. The amount of nitrogen in shoots of mite-infested plants peaked earlier than in controls, and reached maximum values that were 50–69% of the controls. Early infestation (at the onset of reproductive growth) had a greater effect than infestations initiated during active reproductive growth. The concentration of nitrogen in leaves declined faster in mite-infested plants than in controls, mostly due to accelerated leaf senescence. This rapid decline in leaf nitrogen concentration could be one of the factors involved in the collapse of mite colonies in heavily infested plants. Nitrogen concentration of stems and reproductive organs was generally greater in mite-infested plants than in controls. Allometric analysis showed that this was related to both the small size of mite-infested plants, and true increases in nitrogen content probably associated with translocation from senescing leaves.

Monitoring leaf nitrogen in wheat using canopy reflectance spectra

2006 ◽  
Vol 86 (4) ◽  
pp. 1037-1046 ◽  
Author(s):  
Yan Zhu ◽  
Yingxue Li ◽  
Wei Feng ◽  
Yongchao Tian ◽  
Xia Yao ◽  
...  
Keyword(s):  
Nitrogen Concentration ◽  
Leaf Nitrogen ◽  
Reflectance Spectra ◽  
Nutrition Status ◽  
Nitrogen Accumulation ◽  
Canopy Reflectance ◽  
Leaf Nitrogen Concentration ◽  
Non Destructive ◽  
N Status ◽  
Leaf N

Non-destructive monitoring of leaf nitrogen (N) status can assist in growth diagnosis, N management and productivity forecast in field crops. The objectives of this study were to determine the relationships of leaf nitrogen concentration on a leaf dry weight basis (LNC) and leaf nitrogen accumulation per unit soil area (LNA) to ground-based canopy reflectance spectra, and to derive regression equations for monitoring N nutrition status in wheat (Triticum aestivum L.). Four field experiments were conducted with different N application rates and wheat cultivars across four growing seasons, and time-course measurements were taken on canopy spectral reflectance, LNC and leaf dry weights under the various treatments. In these studies, LNC and LNA in wheat increased with increasing N fertilization rates. The canopy reflectance differed significantly under varied N rates, and the pattern of response was consistent across the different cultivars and years. Overall, an integrated regression equation of LNC to normalized difference index (NDI) of 1220 and 710 nm of canopy reflectance spectra described the dynamic pattern of change in LNC in wheat. The ratios of several near infrared (NIR) bands to visible light were linearly related to LNA, with the ratio index (RI) of the average reflectance over 760, 810, 870, 950 and 1100 nm to 660 nm having the best index for quantitative estimation of LNA in wheat. When independent data were fit to the derived equations, the average root mean square error (RMSE) values for the predicted LNC and LNA relative to the observed values were no more than 15.1 and 15.2%, respectively, indicating a good fit. Our relationships of leaf N status to spectral indices of canopy reflectance can be potentially used for non-destructive and real-time monitoring of leaf N status in wheat. Key words: Wheat, leaf nitrogen concentration, leaf nitrogen accumulation, canopy reflectance, spectral index, nitrogen monitoring

scholarly journals Enhancing the Nitrogen Signals of Rice Canopies across Critical Growth Stages through the Integration of Textural and Spectral Information from Unmanned Aerial Vehicle (UAV) Multispectral Imagery

2020 ◽  
Vol 12 (6) ◽  
pp. 957 ◽  
Author(s):  
Hengbiao Zheng ◽  
Jifeng Ma ◽  
Meng Zhou ◽  
Dong Li ◽  
Xia Yao ◽  
...  
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Nitrogen Concentration ◽  
Leaf Nitrogen ◽  
Spectral Information ◽  
Growth Stages ◽  
Nitrogen Accumulation ◽  
Multispectral Imagery ◽  
Plant Nitrogen ◽  
N Nutrition ◽  
Aerial Vehicle

This paper evaluates the potential of integrating textural and spectral information from unmanned aerial vehicle (UAV)-based multispectral imagery for improving the quantification of nitrogen (N) status in rice crops. Vegetation indices (VIs), normalized difference texture indices (NDTIs), and their combination were used to estimate four N nutrition parameters leaf nitrogen concentration (LNC), leaf nitrogen accumulation (LNA), plant nitrogen concentration (PNC), and plant nitrogen accumulation (PNA). Results demonstrated that the normalized difference red-edge index (NDRE) performed best in estimating the N nutrition parameters among all the VI candidates. The optimal texture indices had comparable performance in N nutrition parameters estimation as compared to NDRE. Significant improvement for all N nutrition parameters could be obtained by integrating VIs with NDTIs using multiple linear regression. While tested across years and growth stages, the multivariate models also exhibited satisfactory estimation accuracy. For texture analysis, texture metrics calculated in the direction D3 (perpendicular to the row orientation) are recommended for monitoring row-planted crops. These findings indicate that the addition of textural information derived from UAV multispectral imagery could reduce the effects of background materials and saturation and enhance the N signals of rice canopies for the entire season.

scholarly journals Cytogenotoxic effects of nitrogen on hydroponic lettuce

2020 ◽  
Vol 36 ◽  
Author(s):  
Alcione da Silva Arruda ◽  
Wesley Costa Silva ◽  
Roberta Camargos de Oliveira ◽  
Ernane Miranda Lemes ◽  
Gabriela da Silva Guimarães ◽  
...  
Keyword(s):  
Nitrogen Concentration ◽  
Calcium Nitrate ◽  
Dry Weight ◽  
Positive Control ◽  
Leaf Nitrogen ◽  
Nitrogen Accumulation ◽  
Fresh Weight ◽  
Shoot Dry Weight ◽  
Nutrient Film Technique ◽  
Nitrogen Concentrations

Nitrogen accumulation in hydroponically-grown lettuce may pose a health risk to consumers. Thus, the objective of this study was to analyze different concentrations of nitrogen applications in hydroponic lettuce cultivation and their effect on toxicity, cytotoxicity and genotoxicity. A nutrient film technique (NFT) hydroponic system was used to grow the lettuce variety “Vanda.” The treatments consisted of different concentrations of nitrogen (in the form of calcium nitrate) in Furlani solution (75, 100, 125 and 150%), a negative and a positive control. The following commercial characteristics were measured: plant fresh weight (PFW), root fresh weight (RFW), shoot fresh weight (SFW), shoot diameter (SD), root dry weight (RDW), shoot dry weight (SDW) and leaf nitrogen (LN). Cytogenotoxicity was indicated by toxicity, cytotoxicity and genotoxicity, which were in turn determined by root length, the mitotic index, chromosomal aberrations and the presence of micronuclei.  The nitrogen concentrations used in this experiment did not cause phenotypic toxicity or cytotoxicity in lettuce roots. The most severe genotoxicity was observed at the 125% nitrogen concentration, which nevertheless did not affect commercial characteristics. Although nitrogen fertilization provides great benefits to agriculture, such as greater yields, indiscriminate use should be avoided since concentrations above recommended rates may induce genotoxicity.

Effects of Soil Alkaline Hydrolyzed Nitrogen Concentration on Biomass and Nitrogen Accumulation Eigenvalues of Cotton after Initial Flowering

2013 ◽  
Vol 39 (7) ◽  
pp. 1257
Author(s):  
Wei-Chao SONG ◽  
Chun-Yu LIU ◽  
Jiao XU ◽  
Ning SUI ◽  
Bing-Lin CHEN ◽  
...  
Keyword(s):  
Nitrogen Concentration ◽  
Nitrogen Accumulation

Variations in the relationship between maximum leaf carboxylation rate and leaf nitrogen concentration

2014 ◽  
Vol 38 (6) ◽  
pp. 640-652 ◽  
Author(s):  
YAN Shuang ◽  
◽  
ZHANG Li ◽  
JING Yuan-Shu ◽  
HE Hong-Lin ◽  
...  
Keyword(s):  
Nitrogen Concentration ◽  
Leaf Nitrogen ◽  
Leaf Nitrogen Concentration ◽  
The Relationship
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