Date of Graduation

5-2021

Document Type

Thesis

Degree Name

Bachelor of Science in Agricultural, Food and Life Sciences

Degree Level

Undergraduate

Department

Horticulture

Advisor/Mentor

Dickson, Ryan

Committee Member/Reader

Worthington, Margaret

Committee Member/Second Reader

McDonald, Garry

Abstract

The objective of the study was to evaluate foliar silicon (Si) applications for effects on the growth and performance of container-grown basil during production and resistance to postproduction wilt in retail. Basil (Ocimum basilicum ‘Genovese’ L.) seedling plugs were transplanted into 10-cm diameter plastic containers with peat-based substrate and grown for 42 d in a polycarbonate greenhouse. Plants were irrigated with fertilizer solution consisting of a 17.0 nitrogen (N)-1.3 phosphorus-14.1 potassium water-soluble fertilizer dissolved in tap water at 150 mg∙L-1 N. Foliar sprays containing sodium silicate at 0, 50, 100, 200, and 400 mg∙L-1 Si mixed with deionized water were applied every 7 d. Spray solutions also contained a non-ionic surfactant at 0. 3 mL∙L-1, and a 100% deionized water spray treatment was included as a no-surfactant control. Data collection consisted of leaf SPAD chlorophyll content, shoot height, shoot fresh and dry mass, and Si concentration in dried shoot tissue for four replicates per treatment. Four remaining replicates per treatment continued for a simulated retail phase, during which all replicate containers were irrigated to saturation with clear (no fertilizer) water and placed an indoor environment. Plants were checked twice daily for visible wilt, and number of days until wilting was recorded. To minimize the variability in daily evapotranspiration caused by fluctuations in the retail environment and temperature, days to wilt was standardized by dividing the total water loss per replicate determined using gravimetric methods by the average daily water loss from evaporation pans. The 0 mg∙L-1 Si and no-surfactant control treatments were combined for greater statistical power as there were no differences in their effects. Single degree-of-freedom contrasts were used to compare the effects of each Si treatment to the non-silicon control. Leaf SPAD chlorophyll content was greater for each Si treatment compared to the control. Shoot dry mass was also greater when Si was applied at 400 mg∙L-1, but there was no effect on shoot fresh mass or height. Shoot Si content increased with spray concentration, ranging from 466 to 882 μg∙g-1 of dry tissue for 0 and 400 mg∙L-1 Si treatments, respectively. Foliar sprays of 200 and 400 mg∙L-1 Si increased the number of days until wilting by 2.2 and 2.5 d, respectively. Based on these results, foliar Si sprays applied during production may be a practical and effective strategy for growers to increase resistance to wilting during retail for basil, with minimal effects on plant growth and quality.

Keywords

Foliar silicon (Si); Service Learning; Basil; fertilizer

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