Reducing fertilizer input combined with application of trichoderma to increase yield, quality of melon and soil microbial functional diversity

Objectives Microbial fertilizers have been proved of beneficial to crop growth and soil environment. The effects of Trichoderma on yield, quality of oriental melon and microbial functional diversity of growing substrate were studied for environmental friendly fertilization management in oriental melon production.

Methods A field experiment was carried out in greenhouse, located in the Horticultural Scientific Research Base of Shenyang Agricultural University, from March to July of 2017. The culture substrate was composed of soil∶peat∶cow manure in ratio of 4∶2∶1, and the tested martial was oriental melon (Cucumis melo var. makuwa Makino), cultivar named ‘Yumeiren’. The nitrogen rate calculated for the optimum yield was urea (N≥46.4%) 25.9 g/plant, and taking it as 100% of the N rate. Nine treatments were designed as: 50% regular urea (T1), 50% controlled-release urea (T2), 50% regular urea + Trichoderma (T3), 50% controlled-release urea + Trichoderma (T4), 30% controlled-release urea + 20% regular urea + Trichoderma (T5), 100% regular urea (T6), 100% controlled-release urea (T7), 150% regular urea (T8) and no nitrogen control (CK). The effects of different treatments on yield, quality of oriental melon and the diversity of soil microbial function were determined and analyzed.

Results Compared with the 100% nitrogen fertilization (T6, T7), reduced 50% N application (T1, T2) improved the fruit quality of mature melon, and T4 not only reduced the nitrate content of melon fruit, but also increased the soluble sugar, Vc, aroma content and the single plant yield. With the increase of nitrogen application rate, the apparent nitrogen use efficiency and nitrogen agronomic efficiency decreased significantly in fertilization treatments, and the difference was significant between T1 to T4 treatments and the 100% and 150% nitrogen treatments (T6 toT8), and the nitrogen recovery efficiency of T3 and T4 treatments were high. The AWCD value of soil microbial diversity in the controlled-release urea treatments (T2, T4, T5, T7) were higher than those of other treatments with the application of regular urea, and T4 treatment had the highest value.

Conclusions Reducing nitrogen fertilizer combined with Trichoderma can promote the growth of melon, improve the quality of ripe melon fruit, and increase the yield of single melon and soil microbial functional diversity. Reducing 50% of nitrogen input combining controlled-release urea and Trichoderma has satisfactory performance.