Effects of Nitrogen Exponential Fertilization on Growth and Nutrient Concentration of Hydrangea macrophylla Seedlings

Slow growth rate restricts the development and growth of seedlings due to nutrients deficiency or nutrient imbalance.Exponential fertilization can enhance the internal nutrient reserves in seedlings at the nursery-stage and strengthen their resistance to adverse conditions.In this study,nitrogen requirements for producing Hydrangea macrophylla‘Hanatemari’that robust seedlings,nutrient dynamics,biomass and growth,was examined utilizing exponential fertilization.The potted seedlings were fertilized with urea under exponential regime at rates of 0.5,1.5 and 2.0 g nitrogen/plant(EF1,EF2,and EF3),respectively.In addition,an unfertilized group treated with equal volume of deionized water was used as control.The results showed that seedlings under 1.5 g N/plant(EF2)had the highest plant growth index and total biomass.The nutrient concentrations of different organs varied in different fertilization treatments.Based on the results of current study,it is concluded that 1.5 g N/plant(EF2)is suitable exponential fertilization treatment for the culture of hydrangea seedlings.Our treatments results showed that 2.0 g N/plant is not suitable for seedling culturing,because of serious nutrient toxicity.These findings will help to improve seedling quality and strengthen the production of H.macrophylla for plantation.

N-Exponential Fertilization Could Affect the Growth and Nitrogen Accumulation of Metasequoia glyptostroboides Seedling in a Greenhouse Environment

Metasequoia glyptostroboides(M.glyptostroboides)is a unique plant species related to relic flora in China.It plays a positive role in afforestation and its long-term protection with high paleoclimate research value.However,due to the nutrients-supply deficiency,it is a big challenge to cultivate the high-quality seedlings of M.glyptostroboides.In this study,a pot experiment in a greenhouse environment was carried out to identify the effect of N-exponential fertilization on the growth and nutrient distribution of M.glyptostroboides seedling.The M.glyptostroboides rooted seedlings with 12-month growth were chosen.Different N fertilizer levels with conventional fertilization(CF:5.0 g seedling^(−1)),exponential fertilization including EF1,EF2,EF3 and EF4 were determined.The relevant growth indexes were measured after 210-day growth.The results indicated that non-significant differences in seedlings’height and ground diameter were found among the above treatments(P>0.05);At the same time,N-exponential fertilization promoted the M.glyptostroboides’s biomass in different organs(P<0.05),with the maximum total biomass under EF3 treatment.The N accumulation in root and stem of the N-exponential fertilization treatments were increased in to some extent(P<0.05).The maximum N accumulation was also found under EF3 treatment.Therefore,steady-state nutrition and superior growth performance of M.glyptostroboides could be obtained by N-exponential fertilization of 5.0 g cutting^(−1).