In order to determine how to reduce the chalkiness of rice grains through irrigation modes and nitrogen (N) fertilizer management. The experiment was designed using three irrigation modes (flooding (W1), dry–wet alternating (W2), and dry alternating (W3)), three N application strategies (under 150 kg ha−1, the application ratio of base:tiller:panicle fertilizer (30%:50%:20% (N1), 30%:30%:40% (N2), and 30%:10%:60% (N3)), and zero N as the control (N0) in 2019 and 2020. The results revealed that water–nitrogen interactions had a significant or extremely significant effect on the chalkiness characteristics of the superior and inferior grains. Compared with W1 and W3 treatments, W2 coupled with the N1 application strategy can further optimize grain filling characteristics and canopy microclimate parameters, thereby reducing grain chalkiness. Correlation analysis revealed that increasing grain filling parameters (Gmax or Gmean) and mean grain filling rates (MGRs) during the mid-filling stage in superior grains of the primary branches and inferior grains of the secondary branches, which were important factors in water–nitrogen interaction effects, could further reduce chalkiness. Improving the canopy microclimate (daily average temperature difference and daily average light intensity difference) during the early-filling stage for inferior grains and the mid-filling stage for superior grains could be another important method to reduce chalkiness.
l - and d -lactide polymerization kinetics using phenoxy-imine ligands of the type Me 2 Al[O-2- tert- Bu-6-(C 6 F 5 N=CH)C 6 H 3 ] in the presence of n -butanol and benzyl alcohol by ring-opening polymerization into polylactide are investigated. Effects of initiator concentration, catalyst concentration, polymerization temperature, and time on the molecular weight of poly- l -lactide are also investigated. Purification and drying of l -lactide are found to significantly influence the polymerization kinetics and the final molecular weight achieved. Ultrahigh molecular weight poly( l -lactic acid) PLLA ( M w = 1.4 × 10 6 g/mol with Đ = 1.8) and ultrahigh molecular weight poly( d -lactic acid) PDLA ( M w = 1.3 × 10 6 g/mol with Đ = 2.0) are obtained when polymerization is performed with a molar ratio of monomer to catalyst (LA/Al) of 8000 for 72 h at 120 °C in the presence of benzyl alcohol with conversions of 96 and 91%, respectively. We report for the first time the synthesis of ultrahigh molecular weight poly- l - and d -lactide using the Me 2 Al[O-2- tert -Bu-6-(C 6 F 5 N=CH)C 6 H 3 ] catalyst. The identified catalyst is found to be suitable for the synthesis of a broad range of molecular weights.
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