Assessing the Nitrogen Nutritional Status of Young Non-Bearing ‘Rocha’ Pear Trees Grown in a Mediterranean Region by Using a Chlorophyll Meter

Abstract

2 To find an alternative tool to chemical analysis for assessing the nitrogen (N) nutritional status, the SPAD-Minolta-502 portable chlorophyll meter was tested in one-to three-years-old 'Rocha' pear trees fertilized with 0, 10, 20 and 40 kg N ha −1 year −1 . SPAD readings in the third and fourth fully expanded leaves were as responsive to N fertilization as leaves sampled for foliar chemical analysis (medium third of one-year-old shoots), but individual leaves showed heterogeneous chlorophyll patterns. SPAD readings in leaves sampled at 60 and 110 days after full bloom (DAFB) related linearly with leaf N concentration but significant relationships could also be obtained later. Assuming an optimum leaf N concentration of ≥20 g kg −1 dry weight, SPAD readings ≥33 in leaves sampled at 60{110 DAFB corresponded to a good nutritional N status of young pear trees, making this diagnostic technique more practical, non-destructive and inexpensive, compared with chemical leaf analysis.

The Pear Tree Response to Phosphorus and Potassium Fertilization

“…The available P content, in general, increased in the 0-10, 10-20 and 0-20 cm layers along with the rate of phosphate fertilizer applied in all the crop seasons evaluated (Table 3). Thus, there was a trend toward increase in the total P content in the whole leaves of the pear trees in the second and third crop seasons evaluated, which shows that the organ, the whole leaf, the collection position in the plant and the collection period described by NETO et al (2011) are sensitive in diagnosing the increase in the P content within the plant. In addition, it was seen that in the 2010/2011 crop season, even though increase in the total P content in the whole leaves was not observed with the increase in the soil nutrient content, the content in the leaves, at all the different rates of phosphate fertilizer application, was interpreted as normal (1.5-3.0 g kg -1 ) (BOTELHO et al, 2010), which was also observed in the 2011/2012 crop season.…”

Insect Pollination, More than Plant Nutrition, Determines Yield Quantity and Quality in Apple and Pear

“…The value given by the SPAD is an arbitrary unit that ranges from 0 to (theoretical) infinite; the greater the value, the higher the plant vigor is. SPAD units are a good indicator of plant nutrition, and several studies provide regression equations that allow us to convert the SPAD units to nitrogen concentration (Neilsen et al 1995, Porro et al 2001, Neto et al 2011. Fruit quantity and quality…”

Chlorophyll Content of Aphid-Infested Seedling Leaves of Fifteen Maize Genotypes

“…Portable leaf-clip-type chlorophyll meters perform rapid, repetitive and nondestructive estimates of Chl concentrations in living plants (Hawkins et al, 2009;Jinwen et al, 2009;Coste et al, 2010;Gholizadeh et al, 2011;Shrestha et al, 2012;Ghosh et al, 2013). The use of these reliable and advanced instruments for measurement of green pigment content is not restricted to controlled laboratory bioassays but can be extended to experiments in the plants' natural environment (Uddling et al, 2007;Ruiz-Espinoza et al, 2010;Neto et al, 2011;Cerovic et al, 2012). SPAD-502 chlorophyll meters have been used to obtain accurate measurements in arbitrary SPAD units reflecting absolute foliar Chl concentrations (Arunyanark et al, 2008;Marenco et al, 2009;Mielke et al, 2010;Ling et al, 2011;Shrestha et al, 2012).…”