Effects of slow/controlled release fertilizers on root morphological and physiological characteristics of rice

Effects of different types of nitrogen fertilizer, including conventional urea applied as single basal application (F1), normal urea management (F2), sulfur coated slow release fertilizer (F3) and resin coated controlled release fertilizer (F4), and different transplanting seedling ages, including 3-leaf (T1), 5-leaf (T2) and 7-leaf (T3), on root morphological and physiological characteristics of rice (cultivar of F you 498) were studied using the split block experiment design. The slow/controlled release fertilizer whose nutrient release rate is basically consistent with fertilizer requirement of crop is used as a new type fertilizer with long time affections. In some crops, it realizes onetime basal fertilizer application and thus simplifies fertilizer application technology thoroughly. The results show that nitrogen fertilizer can alleviate adverse impact of later transplanting on the growth of roots. The total root lengths, root volumes and root bleeding intensities of the 3-leaf and 5-leaf are higher than those of the 7-leaf at the bearing stage. Compared to conventional urea application, applying the slowcontrolled release fertilizer increases root dry weight, total root length, root volume and root bleeding intensity significantly in the late growing stages which are the critical period for rice growth. The root dry weight, total root length, total root surface area, root bleeding intensity and root weight distribution ratio below 10 cm soil layer have a significant relationship with the yield at the maturing stage. Different transplanting seedling ages and nitrogen types affect rice growth mainly through total root length, root volume and root bleeding intensity. At different transplanting seedling ages, application of slowcontrolled release fertilizer can increase the yield by promoting root growth and deep distribution, keeping high root activities. In combination with morphological and physiological characteristics and the yield, the 5-leaf transplanting seedling age and resin coated controlled release fertilizer can be the references for alleviating the contradiction of proceeding crops and nitrogen use methods in local region.