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AbstractFoliar tissue sampling has been used in the greenhouse industry to diagnose nutrient disorders for many crops. Leaf tissue nutrient standards for pentas (Pentas lanceolata Forssk.) were non-existent before a recent rate study was published. This study expands prior work and presents a novel method to create data-driven nutrient interpretation ranges by fitting models based on the Sufficiency Range Approach (SRA) to provide more refined ranges of deficient, low, sufficient, high, and excessive values for 11 essential elements based on n = 407 data points. Data distributions were analyzed by fitting Normal, Gamma, and Weibull distributions. This study establishes using SRA to create refined interpretation ranges for pentas foliar nutrient analysis results with a higher degree of precision than what is currently available to the greenhouse industry for diagnosing fertility status. [ABSTRACT FROM AUTHOR]

In the absence of controlled sufficiency studies, foliar interpretations for many horticultural crops are based on survey concentrations from small data sets. In addition, both survey and sufficiency ranges provide little interpretation regarding zones that are above or below the concentration range deemed "sufficient." While providing a critical initial set of ranges, it was based on a limited set of data and therefore improvements in interpretation of data are needed. This study presents a novel method based on 1950 data points to create data-driven nutrient interpretation ranges by fitting models to provide more refined ranges of deficient (lowest 2.5%), low (2.5% to 25%), sufficient (25% to 75%), high (75% to 97.5%), and excessive (highest 2.5%). Data were analyzed by fitting Normal, Gamma, and Weibull distributions. Corresponding P values were calculated based on the Shapiro-Wilk test for normality for the Normal and Gamma distributions, and the Kolmogorov-Smirnov test was used for the Weibull distribution. The optimal distribution was selected based on the lowest Bayesian Information Criterion (BIC) value and visual fitness. The Weibull distribution best represented nitrogen, phosphorus, potassium, calcium, manganese, zinc, and copper, and the Gamma distribution best represented magnesium, sulfur, iron, and boron. Using the selected distributions, we propose a refined set of nutrient evaluation ranges for greenhouse-grown lettuce. These refined standards will aid growers and technical specialists in more accurately interpreting leaf tissue sample data. [ABSTRACT FROM AUTHOR]

Many abiotic factors impact the yield and growth of Cannabis sativa (cannabis). Cannabis has been reported to be a bio-accumulator of heavy metals. For growers who are targeting floral production and other byproducts for human consumption, this is a concern. Silicon (Si) has been examined as a beneficial plant element to limit the uptake of heavy metals in a variety of crops. The objective of this study was to determine the impact of Si on heavy metal micronutrient uptake and plant growth for greenhouse-cultivated cannabis at varying Si substrate amendments. ‘Auto CBG’ plants were grown in a 70:30 peat:perlite substrate with one of three varying calcium silicate (CaSiO3) (Si) substrate amendment rates, Si0X, Si0.5X, or Si1X (of 0.0, 1.04, and 2.07 kgm-3 CaSiO3), and one of three micronutrient fertility treatments, M1X [0.49 boron (B), 0.19 copper (Cu), 4.02 iron (Fe), 0.99 manganese (Mn), 0.01 molybdenum (Mo), and 0.20 zinc (Zn) mgL-1], M2X, or M4X, using a modified Hoagland’s solution, creating a 3 × 3 factorial. Plants grown with a Si1X substrate amendment exhibited a significantly lower iron concentration in the foliage and root tissue when compared with those grown in a substrate without Si. After 6 weeks of growth, Si0X plants that received a M4X fertility rate exhibited greater foliar micronutrient concentrations of B, Mn, Zn, Fe, and Cu than plants that received a Si substrate amendment when provided a M4X fertility rate. Additionally, lower micronutrient concentrations in floral tissue were observed in plants that received a Si substrate amendment for M2X and M4X when compared with plants that did not. Silicon substrate amendments had no impact on the cannabinoid concentration or plant growth metrics after 12 weeks of growth. This research suggests that using a Si substrate amendment in a greenhouse production system can limit excessive uptake and accumulation of micronutrients in the foliage, roots, and floral material of cannabis without negative impacts on plant growth or cannabinoid concentrations. [ABSTRACT FROM AUTHOR]