Effects of Nitrogen Fertilizer on Grain Quality of Different Cultivars of Japonica Rice

Three cultivars of Japonica rice:hybrid Japonica rice,inbred Japonica rice and soft Japonica rice,were used to study the effects of recommended nitrogen fertilizer on grain quality including milling,appearance,nutrition,cooking and eating quality,pasting property and their relationships in direct seeding rice.Recommended nitrogen fertilizer improved the brown rice rate,the milled rice rate,and the protein content;increased the chalky grain rate and the chalkiness,and reduced the amylose content,palatability and pasting viscosity.The nitrogen fertilizer caused the appearance,the cooking and the eating quality to deteriorate.Lower amylose content and protein content were found in soft Japonica rice compared to those in hybrid Japonica or inbred Japonica rice under the condition of the recommended rate of nitrogen fertilizer,contributing to high cooking and eating quality.Correlation analysis indicated that palatability was negatively correlated with amylose content,protein content,hardness and gelatinization temperature,and was positively correlated with stickiness,peak viscosity and breakdown.Therefore,the decreased amylose and protein content of the soft Japonica rice cultivar planted under the condition of the recommended rate of nitrogen fertilizer is beneficial to achieving high taste quality.

温度和光照强度对浒苔生长和光合生理特性的影响

实验以浒苔(Ulva prolifera)为材料,设置3个温度(20℃、25℃及30℃)和两个光照强度(低光:70μmol/m^2·s;高光:250μmol/m^2·s),通过测定不同培养条件下浒苔的生长、叶绿素含量、光合荧光参数、呼吸速率及光合放氧速率,初步探讨温度和光照强度对浒苔生长和光合特性的复合效应,为研究浒苔绿潮爆发及规模化养殖提供一定的参考。结果显示:1)光照强度的升高显著促进浒苔的生长;温度从20℃升高至25℃对浒苔生长的影响不显著,但升高至30℃具有显著的抑制作用。2)30℃、250μmol/m^2·s条件下,浒苔的有效光化学效率(F_v'/F_m')及最大相对传递速率(r ETR_(max))显著降低。3)高光条件下,25℃时浒苔具有较高的暗呼吸(R_d)及净光合放氧速率(P_n);20℃时浒苔的暗呼吸和总光合放氧速率的比值(Rd/Pg)最低。整体来说,光照强度的适度增加提高了浒苔对升温的适应。