Use of a Portable Rapid Analysis System to Measure Nitrate Concentration of Nutrient and Soil Solution, and Plant Sap in Greenhouse Vegetable Production

A rapid analysis ion-selective electrode (ISE) system for measurement of [NO3−] in nutrient solution (NS), soil solution (SS) and petiole sap (PS) was evaluated. For each material, there were 797–2010 samples from 5 to 6 different crops, and from 2 to 4 different species. Accuracy was evaluated by linear regression (LR) with laboratory analysis (automated colorimetry, Cd reduction), and by relative error (RE), the average percentage deviation from laboratory analysis. For NS, the LR was y = 0.982x + 0.76, R² = 0.962 (n = 2010), for combined data from 5 crops (3 pepper, 2 cucumber). For SS, the LR was y = 0.975x + 1.13, R² = 0.965 (n = 797), for combined data from 5 crops (3 pepper, 2 cucumber). For undiluted PS, the LR relationship was y = 0.742x + 168.02, R² = 0.892 (n = 1425), for combined data from 6 crops (3 pepper, 2 cucumber, 1 melon). The underestimation was most pronounced at [NO3−] of >1500 mg NO3−–N L−1. For diluted petiole sap (dilution by 10 for pepper and melon, 5 for other species), the LR relationship was y = 1.010x + 99.26, R² = 0.927 (n = 1182), for combined data from 6 crops (2 pepper, 2 cucumber, 1 melon, 1 tomato). RE values for all measurements in composite datasets were 14%, 22%, 24% and 25% for NS, SS, undiluted PS and diluted PS respectively, and they were lower in concentrations most likely to be measured in practical on-farm work. The ISE system measured [NO3−] in NS, SS and diluted PS with sufficient accuracy to effectively guide on-farm decision making.

Rapid NPK diagnosis in tomato using petiole sap analysis with the DRIS method

ABSTRACT One of the factors determining success in tomato production is plant nutrition. The diagnosis and recommendation integrated system (DRIS) is a tool used to obtain fertilizer recommendations. The objective of this study was to determine DRIS indices using petiole sap analysis (PSA) and compare them with those obtained using leaf analysis in two tomato cultivars grown under greenhouse conditions. A complete randomized design with eight treatments and 60 plants per experimental unit was used. To determine whether employing PSA with the DRIS methodology can provide a reliable diagnosis of fertilization, doses of some elements, such as N, P, or K, were reduced by 30% and supplied to two tomato cultivars, namely, Cid and Moctezuma. The indices for PSA-DRIS and DRIS were estimated. R2 values greater than 0.84 were obtained for the relationships between the leaf concentrations and petiole extract (PE) concentrations of some elements in both tomato cultivars. The PSA-DRIS method detected 62.5% of the cases of deficiency identified via DRIS. The PSA-DRIS method is a low-cost way to rapidly fertilize recommendations in tomato.

Monitoreo de la Savia del Peciolo de Vegetales

A medida que los productores y consultores comienzan a usar la tecnología de monitoreo de savia, surgen preguntas sobre los procedimientos del monitoreo de savia. Las siguientes guías deberían ayudar a las personas que actualmente usan o están interesadas en usar el monitoreo de savia. La mayoría de estas guías se han desarrollado a través de investigaciones en Florida, o se basan en la experiencia de campo. This is the Spanish translation of CIR1144/CV004, Plant Petiole Sap-Testing For Vegetable Crops. Written by George Hochmuth, translated by Maria Paz Kinslow, and published by the UF/IFAS Horticultural Sciences Department.

Approach to Petiole Sap Nutritional Diagnosis Method by Empirical Model Based on Climatic and Growth Parameters

The aim of this work is to evaluate the relationship between the nutrient concentration in petiole sap and different agronomic and climatic variables for a tomato crop grown in a greenhouse in Mediterranean conditions. In addition, the persistence of the nutrient concentration in petiole sap was investigated with the aim of determining the sampling period that implies the best trade-off nutritional information. The experiment consisted of the selection of 20 sampling points inside the greenhouse. The samples of petiole, fully expanded leaf, and soil solution samples were collected weekly from 86 to 163 days after transplanting. Chloride, NO3−-N, H2PO4−-P, Na+, K+, Ca2+, and Mg2+ concentrations were determined in petiole sap and soil solution obtained by suction cups. Nitrogen, P, K, Cl, and Na concentrations were also determined in leaf. Finally, the petiole sap nutritional diagnosis method is the highest sensitive nutritional diagnosis method which compares soil solution and nutrient leaf content related to yield, and the statistical analysis performed in this research demonstrates that crop evapotranspiration (ETc), vapor pressure deficit (DPV), and leaf area index (LAI) are considered the most significant variables that allow the development of these empirical prediction models regarding nutrient concentration in petiole sap.

ASSESSING NITROGEN NUTRITIONAL STATUS, BIOMASS AND YIELD OF COTTON WITH NDVI, SPAD AND PETIOLE SAP NITRATE CONCENTRATION

SUMMARYCanopy normalized difference vegetation index (NDVI), soil plant analysis development (SPAD) reading and petiole sap NO3−‒N concentration are increasingly used as quick and non-destructive methods to monitor plant N nutrition and growth status and predict yield of crops. However, little information is available on the comparisons of these three methods in assessing N nutrition, growth and yield for cotton (Gossypium hirsutum L.). Four N rates (0, 34, 67 and 101 kg N ha−1) under two cover conditions [no cover crop and hairy vetch (Vicia villosa) crop] in a 33-year long-term field trial were used to evaluate how canopy NDVI, SPAD reading (related to chlorophyll content) and petiole sap NO3−‒N concentration (conventional method) are able to assess N nutrition and plant biomass and predict yield for cotton. Canopy NDVI and SPAD readings responded less sensitively to N rates than petiole sap NO3−‒N. The responses of NDVI and SPAD reading to N rates were generally reduced due to the winter cover crop with hairy vetch. Significant and positive correlations existed mostly among NDVI, SPAD reading, and petiole sap NO3−‒N concentration. Canopy NDVI during mid-bloom to late bloom and SPAD reading during early bloom to late bloom were effective alternative methods for assessing cotton N nutrition status. The SPAD reading at late bloom was an effective parameter to estimate cotton biomass. The NDVI at early square and SPAD reading during early square to mid-bloom were effective for cotton yield prediction.