Evaluation of real-time nutrient analysis of fertilized raspberry using petiole sap

Abstract

The time delay in receiving conventional tissue nutrient analysis results caused red raspberry (Rubus idaeus L.) growers to be interested in rapid sap tests to provide real-time results to guide immediate nutrient management practices. However, sap analysis has never been conducted in raspberry. The present work aimed to evaluate the relationship of petiole sap nitrate (NO3–), potassium (K+), and calcium (Ca2+) concentrations measured using compact ion meters and leaf tissue total nitrogen (TN), potassium (K), and calcium (Ca) concentrations measured using conventional tissue nutrient analysis. The relationship of petiole sap NO3– and leaf tissue TN concentrations with plant growth and production variables was also explored. Fertilizer treatments of urea were surface applied to raised beds of established “Meeker” floricane red raspberry plots at control, low, medium, and high rates (0, 34, 67, and 101 kg N ha–1, respectively) in 2019 and 2020. The experiment was arranged in a randomized complete block design with three replications. Whole leaves were collected from representative primocanes in mid- and late- July and August 2019 and 2020 (i.e., four sampling time points per year). At each sampling time point, a subsample of leaves was used for petiole sap analyses of NO3–, K+, and Ca2+ concentrations using compact ion meters, and conventional tissue testing of leaf tissue TN, K, and Ca concentrations, respectively. There were no interactions between N fertilizer rate and year nor between N fertilizer rate and sampling time. No significant differences were found due to N fertilizer rate for petiole sap NO3–, K+, Ca2+ nor leaf tissue TN, K, Ca concentrations. However, significant year and sampling time effects occurred in measured petiole sap and leaf tissue nutrient concentrations. Overall, the correlations between petiole sap NO3– and leaf tissue TN, petiole sap Ca2+ and leaf tissue Ca, petiole sap K+ and leaf tissue K concentrations were non-strong and inconsistent. Future research is warranted as the interpretation of correlations between raspberry petiole sap and leaf tissue nutrient concentrations were inconclusive.

Sample Temperature Affects Measurement of Nitrate with a Rapid Analysis Ion Selective Electrode System Used for N Management of Vegetable Crops

“…These results are of considerable practical importance given the many research e.g., [18,20,21,31,34] and Extension publications e.g., [19,22] that have used these ISE meters or their predecessor (Cardy nitrate meter) for measurement of [NO 3 − ] to assist in N management of vegetable crops. In numerous studies, the combined use of these ISE meters and petiole sap analysis were presented as a crop N management package e.g., [30,32,33,41,42]. While a number of studies have evaluated the accuracy of these or similar ISE systems with a particular type of sample (petiole sap or soil solution) [18,19,31,35,[44][45][46], none of these considered how temperature affected the accuracy of measurement.…”

“…Measurement may take place immediately following storage in a refrigerator, on samples obtained from plants and fertigation systems at very different ambient temperatures, or from soils subject to appreciable temperature variation. Given the strong and on-going interest in using ISE systems for on-farm measurement of [NO 3 − ], e.g., [13,18,19,22,23,29,33,41,42], there is a need to assess how sample temperature affects the accuracy of [NO 3 − ] measurement. In this study, the effects of sample temperature on two similar models of a commercially available ISE were examined.…”

Evaluation of the Quality of Raspberries (Rubus idaeus L.) Grown in Balanced Fertilization Conditions

“…The author showed that a high dose of nitrogen (178 kg N ha•ha −1 ) did not increase the yield compared with a low dose of N fertilizer (40 kg N ha•ha −1 ). The lack of effect of the dose of N on the yield and quality of fruit was also observed by scientists conducting an experiment with the red cultivar 'Meeker' in north-western Washington (USA) [48]. According to the authors, this could be related to the mineralization of nutrients in the soil and the use of nutrient reserves accumulated in the plant.…”