Carol A. Miles

Biodegradable mulch performed comparably to polyethylene in high tunnel tomato (Solanum lycopersicum L.) production.

BACKGROUND High tunnels in the cool climate of north western Washington state improve the growing environment for crops otherwise suited to warmer climates. Biodegradable mulch may improve the sustainability of high tunnel vegetable production if it performs comparably to polyethylene. Four biodegradable mulch treatments (BioAgri, BioTelo, WeedGuardPlus and SB-PLA-10/11/12) were compared to black polyethylene and bare ground in high tunnels and open field settings to assess the impact of production system and mulch treatment on weed control, tomato yield, and fruit quality. RESULTS Fewer weeds grew in high tunnels than in the open field. High tunnels increased total and marketable fruit yields and increased individual fruit weight. High tunnel production increased juice content and pH of tomato fruit, but decreased total soluble solids, titratable acidity, and total phenolics compared to the open field. All mulch treatments except SB-PLA-10 controlled weeds. BioAgri, BioTelo and polyethylene increased total yields by 20%, though marketability was reduced 14% compared to bare ground and WeedGuardPlus treatments. CONCLUSION High tunnels can improve tomato yield and affect fruit quality in north western Washington. Biodegradable plastic mulches performed comparably to polyethylene in weed control, tomato yield, and fruit quality and may, therefore, improve the sustainability of high tunnel vegetable production.

Influence of Plant Part on Nitrate Concentration in Lettuce and Spinach

ABSTRACT The concentration of nitrate-nitrogen (NO3-N) varies between lettuce (Lactuca sativa L.) and spinach (Spinacia oleracea L.). Nitrate is potentially harmful if consumed in large amounts by humans; therefore, understanding which cultivars and plant parts concentrate NO3-N can be useful in developing approaches to reduce dietary NO3-N intake. We determined NO3-N concentration and distribution in cultivars of field-grown lettuce and spinach. In 2006, NO3-N concentration was highest in the outer leaf whorl and lowest in the center of spinach; no difference was found in lettuce. In 2007, overall soil and tissue NO3-N concentrations were lower and there was no interaction between plant part and species or cultivar and no difference among leaf whorls; all cultivars had higher NO3-N concentrations in the midrib and petiole than in the leaf. Differences in NO3-N concentration and distribution suggest that practices such as cultivar selection and selective removal of high NO3-N parts can lower NO3-N consumption by humans.

Exploring the role of local heirloom germplasm in expanding western Washington dry bean production

ABSTRACT Increasing production of dry beans (Phaseolus vulgaris L.) could contribute to the sustainability of regional agricultural systems. This study in western Washington identified 24 distinct dry bean varieties grown in the region for 20–130 years; varieties originated from diverse geographic areas and were maintained because growers valued the culinary, visual, and agronomic traits as well as history and marketability. Primary barriers to increased production were access to scale-appropriate equipment and drying beans in the field prior to harvest. Locally conserved germplasm may have value in participatory plant breeding projects that recognize the contributions of regional farmers.

Grafting Effects on Eggplant Growth, Yield, and Verticillium Wilt Incidence

Verticillium wilt (caused by Verticillium dahliae Kleb.) is common and widespread in Washington State. Plant growth, yield, and verticillium wilt were evaluated for ‘Epic’ eggplant (Solanum melongena L.) grafted onto ‘Beaufort’ and S. aethiopicum L. rootstocks in two naturally infested fields and two greenhouse studies in 2010 and 2011. In the field, ‘Beaufort’-grafted eggplant had the greatest stem diameter and plant height in 2011, the lowest verticillium wilt severity in both years, and the highest marketable fruit weight in 2010 compared to non-, self-, and S. aethiopicum–grafted eggplants. In the greenhouse, when inoculated with V. dahliae, ‘Beaufort’-grafted eggplants had less wilting than S. aethiopicum–grafted eggplants, indicating that ‘Beaufort’ is the superior rootstock for disease management.

Sensory Comparison of Ciders Produced from Machine- and Hand-harvested ‘Brown Snout’ Specialty Cider Apples Stored at Ambient Conditions in Northwest Washington

Machine harvest of ‘Brown Snout’ specialty cider apple (Malus ·domestica) has been shown to provide yield and juice quality characteristics similar to that of hand harvest. In this 2-year study, the sensory perception (color, aroma, flavor, mouthfeel, taste, and aftertaste) of ciders produced from machine-harvested and hand-harvested fruit that were ambient stored (56 F) 0–4 weeks postharvest were compared using a trained panel and electronic tongue (e-tongue). For nearly all sensory attributes evaluated, the trainedpanelists scored the2014machine-harvested samples higher than the 2014 hand-harvested samples. Some of the key sensory differences included a darker color, a more astringent and heated mouthfeel, and a more sour taste of the machine-harvested samples than the hand-harvested samples. Trained panelists perceived no differences due to the harvestmethod among the 2015 samples for any of the sensory attributes evaluated. The e-tongue demonstrated good discrimination (index value = 95) of 2014 samples, but poor discrimination (index value = L0.5) of 2015 samples, mirroring the year-to-year variation experienced by the trained panelists. Overall, the e-tongue demonstrated a response to metallic and sour that was more associatedwith themachine-harvested samples and a response to sweet and umami that was more associated with the hand-harvested samples. These results demonstrate that cidermade frommachine-harvested fruit can have a different sensory profile than cider made from hand-harvested fruit. A consumer tasting panel should be conducted next to provide an indication ofmarket response to the differing sensory profiles, qualifying the impact of harvestmethod.Results also indicate that ambient storage (56 F) of fruit up to 4 weeks may not impact cider sensory attributes; however, cider apple growers should avoid ambient storage of machine-harvested fruit given the significant yield losses demonstrated in previous studies. Variation in cider quality due to year of harvest was most likely a result of differences in the hand-harvest technique between the 2 years, specifically more fruit bruising in 2014 than in 2015, demonstrating the importance of harvesting fully mature fruit with a standard protocol so as to supply a consistent raw material to cider producers. The e-tongue produced variable results compared with trained panelists and more development is needed before it can be incorporated into cider sensory evaluation protocol.