ObjectiveWater and fertilizer are two key factors to promote plant growth, thus, it is important to study their coupling effects on growth and nutrient status of Catalpa bungei seedlings.

MethodThe pot experiment with Catalpa bungei seedlings in three different water levels (30%, 50% and 70% saturated water content(FWC)) with four fertilization levels of T1(N 0g, P 0g, K 0g), T2(N 2g, P 1g, K 1.5g), T3(N 4g, P 2g, K 3g), T4(N 6g, P 3g, K 4.5g) was conducted to study the coupling effects of water and fertilizer on growth, nutrient absorption and fertilizer utilization.

ResultThe interactive effects of water and fertilizer coupling on morphological indexes of Catalpa bungei seedlings were not significant. Root collar diameter, height, and biomass of seedlings decreased with rising water level, reaching the top at 30% saturated water content, but firstly increased and then decreased with increasing fertilization level, reaching peak at T3 fertilization level. The nutrient content of seedlings reached a luxury nutrient state at T3 treatment, meanwhile seedling height, root collar diameter, biomass and nutrient content of seedlings were the highest. If more fertilizers were applied on seedlings, it would occur toxic effects. Since at T3 treatment, although the nutrient concentration of seedlings was increasing, the morphological indexes and nutrient content decreased. There were interactions of water and fertilizer coupling effects on nutrient concentration and nutrient content of Catalpa bungei seedlings. Nutrient content rose with increasing fertilizers, and reached the peak under T3 treatment. When water content was 30% FWC, fertilization had a greater promotion for seedlings of Catalpa bungei.

ConclusionIt proves that water and fertilizer coupling effects promote the quality of seedlings. Furthermore, 30% FWC and T3 treatment was the best combination for cultivating seedlings of Catalpa bungei.