A quality of forage under optimal condition needs to be evaluated because an optimal condition for high productivity does not guarantee high quality product. In this study, we aimed at investigating a quality of barley grown under optimal conditions for maximizing productivity by comparing its ingredient contents with those under other conditions in plant factory-type fresh forage growing system. To compare the ingredient in barley grown at 4 conditions, we used multivariate analysis of variance (MANOVA) and Tukey’s post-hoc test. The optimal growth condition (20 and 63% of humidity) was applied to the first group (group 1), while other groups were cultivated under 20 / 90% (group 2), 18 / 63% (group 3), and 23 / 63% (group 4). In the analysis, contents of ingredients in each sample were measured at two parts, i.e., roots and shoots. Result showed that roots included 86.68% of moisture, 1.86% of crude-protein, 0.58% of crude-fat, 2.13% of crude-fiber, 195.78 ppm of minerals, and 231.48 μmol/g of amino acids. For shoots, 92.42% of moisture, 2.52% of crude-protein, 0.16% of crude-fat, 1.86% of crude-fiber, 263.78 ppm of minerals, and 208.34 μmol/g of amino acids were contained. When comparing by groups, moisture, crude-fat, and some minerals (Fe, Na, and P) were not significantly different by groups. In contrast, crude-protein, crude-fiber, and few minerals (Ca and K) were different. Overall, the variation in total amount of ingredient was less than 20% among groups, suggesting quality of barley under optimal conditions for productivity was acceptable. In conclusion, the optimal condition for yielding maximal productivity maintains barley quality, but an operating conditions needs to be changed when emphasizing functional aspect of forage.

Response Surface Methodology (RSM) is a widely used statistical analysis for finding an optimal point of a response variable (dependent variable) in accordance with multiple explanatory variables (independent variable). We have previously used RSM to identify optimal temperature and humidity (represented by the amount of water spray) of the fresh forage system for maximizing the growth of barley after 6 days of seeding. Consequently, RSM demonstrated that the optimal growth condition of barley was 19.70 and 1.38 l/h. However, it was not proved by empirical result, we aimed to verify the RSM result through comparative experiments. Experiments were designed four trials with different conditions. The first trial represented optimal conditions obtained from RSM, i.e., 20 and 1.4(l/h), while the rest of trials represented; 1) 20 and 1.8(l/h), 2) 18 and 1.4(l/h), and 3) 23 and 1.4(l/h). After 6 days of seeding, the average barley weight of the first trial was 11,094 g which was the highest yield compared to other trials (10,101 g, 9,757 g, and 10,233 g). This result supports that the RSM successfully predicted the optimal growth condition to be applied for the fresh forage system.