Polyaspartate Urea and Nitrogen Management Affect Nonstructural Carbohydrates and Yield of Rice

Abstract

In rice (Oryza sativa L.), nonstructural carbohydrates (NSC) play an important role in grain yield. To investigate the effects of urea type (polyaspartate urea versus conventional urea) and N management method (farmer's fertilizer practice and optimized N management) on NSC accumulation and remobilization in rice, field experiments were conducted in Wenjiang, China, in 2014 and 2015. Grain yield, effective panicles, and total number of spikelets were positively related to NSC accumulation in aboveground parts and remobilization of stored NSC (RSN) in the stem plus sheath from 20 d after heading to maturity. Polyaspartate urea, in place of conventional urea, increased NSC accumulation in the leaf lamina and the stem plus sheath at the heading stage and promoted RSN in the stem plus sheath from 20 d after heading to maturity, improving grain yield and total aboveground biomass. Compared with farmer's fertilizer practice, optimized N management showed a 5% reduction in NSC accumulation in the stem plus sheath from planting to heading and a 22% decrease in RSN in the stem plus sheath from heading to 20 d after. Optimized N management increased RSN in the stem plus sheath from 20 d after heading to maturity, increasing NSC accumulation in the panicle and grain yield. Using polyaspartate urea with optimized N management may indeed be a practical and feasible way to enhance grain yield of rice in subtropical humid monsoon climates.

Limitation of Unloading in the Developing Grains Is a Possible Cause Responsible for Low Stem Non-structural Carbohydrate Translocation and Poor Grain Yield Formation in Rice through Verification of Recombinant Inbred Lines

“…This observation is consistent with Hirano et al (2005) and Pan et al (2011) that fewer carbohydrates were accumulated in stems at heading under high nitrogen. Recently, Deng et al (2016) partly differed and reported that nitrogen application to rice improves NSC at heading and remobilizes its translocation to grains at later stages of grain development for increase of yield. It is known that rice plant requires carbohydrates to constitute the plant structure, and also needs additional carbon for transformation of the extra inorganic nitrogen absorbed from the growth medium ( Gebbing et al, 1999 ).…”

Polyaspartic acid (PASP)-urea and optimised nitrogen management increase the grain nitrogen concentration of rice

“…PASP-urea, one of the high efficiency fertiliser, is demonstrated to increase grain yield and N use efficiency of crops 21,24 . By using PASP-urea, better synchronisation between N requirement and supply was realised, which contributed to an increase in photosynthetic capacity, dry matter accumulation, as well as effective panicles, grain filling percentage, and grain weight, and thereby significantly improved the grain yield 21,25,27 . It is well demonstrated that increasing the N rate and optimising the timing of N supply usually result in higher N concentration and accumulation in the rice organs 34,35 .…”

“…The previous crop in both years was wheat. Wenjiang had a subtropical humid monsoon climate, with an average air temperature and precipitation of 23.9 °C and 715.0 mm, respectively, during the period from transplantation to harvest (May to September) in 2014, and 24.0 °C and 568 mm, respectively, in 2015 25 . The properties of the top soil layer (0–30 cm) are shown in Table 3.…”

“…The complete experimental details were described previously by Deng et al . 25,27 . In brief, the treatments were as follows: (1) two urea types, conventional urea and PASP-urea were used; (2) two N management methods, two splits N application (180 kg N ha −1 , by which 70% and 30% of N were applied at the basal and tillering stages, respectively) and four splits N application (180 kg N ha −1 , split-applied as 35% at the basal, 15% at the tillering, 30% at the panicle initiation, and 20% at the spikelet differentiation stages); zero-N treatment (CK) with three replicates was set as the control.…”

“…PASP-urea is produced by mixing a certain amount of PASP with conventional urea, and is widely used in crop production in China. Previous studies have demonstrated that PASP-urea increases the N balance in paddy fields, leading to improvement in grain yield, N uptake, and N use efficiency of rice, as well as the accumulation of N in the panicle 21,25,27 . However, there exists limited knowledge of the effectiveness of split N application and PASP-urea on GNC of rice.…”