EFFECT OF NH₄⁺ TO NO₃^- RATIO ON GROWTH, YIELD AND ALBINISM DISORDER OF STRAWBERRY

In soilless culture of strawberries in winter season, there occur a lot of albino fruits whose color remains partially or even totally white. Such an occurrence of albino fruit decreases marketable yield, incurring tremendous economic losses. This study focused on investigating the effect of NH₄⁺: NO₃^- (ammonium:nitrate) ratio on growth, yield and the albinism disorder of strawberry. Four different ratios of NH₄⁺ to NO₃^- (0:100, 10:90, 20:80 and 30:70) in the nutrient solution were examined. The zero NH₄⁺ treatment (0:100) gave the lowest plant growth and fruit yield. Up to the NH₄⁺ ratio of 20%, the more increase in the NH₄⁺ ratio, the more gradual the increase in plant growth. At the NH₄⁺ ratio of 20%, marketable yield increased by 15% as against NH4+ ratio of 0%. Marketable yield began to decrease at the NH4+ ratio of 30%. Within the range of 0~30% NH₄⁺ ratio, albino fruits accounted for only 0.1~0.4% of total production. Albino fruit analysis did not show a significantly higher amount of N.