The suitable percentage of tomato straw compost in graden soil for improvement of tomato flavor

Objectives Vegetable production is large in area in China, which produces large amount of vegetables and plant wastes at the same time. In this study, the composting product of tomato straw waste was attempted as the organic material for tomato production, and the suitable application ratio was compared with conventional substrate.

Methods In a pot experiment, a tomato cultivar of ‘Jinpeng1’ was selected as the test material, and a conventional substrate used for tomato production (total content of NPK ≥ 2%, organic matter ≥ 30%) was used as the control (CK). Six mixture proportions of tomato straw compost with garden soil were setup for the treatments: 0% (T1), 5% (T2), 7.5% (T3), 10% (T4), 12.5% (T5), 15% (T6). Fruit were sampled at ripening stage, and the volatile components and contents of tomato fruits were determined using SPME−GC−MS method. The fruit yield were investigated at last.

Results A total of 73 volatile substances were detected in tomato fruits, including 9 ketones, 25 aldehydes, 19 alcohols, 5 esters and 4 hydrocarbons, and 11 other unclassified components. Of which, the contents of aldehydes and alcohols in tomatoes treated with straw compost were significantly different from those with conventional substrates. The good effect on fruit flavor was in order of T6 > T5 > CK > T4 > T2 > T3 > T1. The total volatile matter contents of T5 and T6 treatment were 81.0% and 137% higher than that of CK tomato, respectively. There were 11 kinds of detected tomato characteristic effect compounds, including three aroma components deciding the flavor of green, fruity and floral. The total contents of tomato characteristic effect compounds of T5 and T6 were increased by 24.8% and 72.2%, respectively, compared with conventional cultivated tomatoes. The yield of T5 treatment was higher than that of T6, and there was no significant difference between T5 treatment and control.

Conclusions Tomato straw compost is proved to be capable of using as organic materials for tomato production. With proper mixture ratio with garden soil, application of tomato straw could significantly improve the flavor of tomato, and obtain satisfactory yield as well. Under the conditions of this experiment, the proportion of 12.5% tomato straw compost is recommended to mix with garden soil for high yield and high quality tomato production.