高温对小白菜品质的影响及模拟研究

为了研究高温胁迫对小白菜品质指标的影响,以‘华王’为试材,于2015年10月—2016年5月进行分批播种试验,设置昼温/夜温为32℃/22℃、35℃/25℃、38℃/28℃共3个梯度,持续处理时间分别为3 d、6 d、9 d、12 d,以25℃/18℃为对照(CK)。各处理结束2 d后测定小白菜外观形态、SPAD值、单株干鲜重和粗纤维、可溶性糖、可溶性蛋白、维C的含量,建立小白菜卷叶率和单位面积产量与最高气温、最低气温、平均气温及持续时间的回归模型,并用实测数据检验模型的模拟效果。结果表明:小白菜单株干重、鲜重、叶片鲜重、叶片长度、叶片宽度、叶柄宽度、SPAD和单位面积产量均随高温胁迫的加剧和胁迫时间的延长而呈降低趋势。随温度的升高和持续时间的延长,叶片内叶柄长度、卷叶率逐渐增加。高温胁迫使小白菜粗纤维含量升高。短期高温胁迫下可溶性糖、可溶性蛋白、维C含量变化不明显,随胁迫时间的延长、胁迫温度升高逐渐降低。通过多元回归方法,分别构建了小白菜卷叶率和单位面积产量与最高处理气温、最低处理气温、平均处理气温及各处理所对应持续时间的关系模型。对模型的检验结果表明,小白菜卷叶率与最低处理温度和最低温度持续时间构建模型模拟效果最好,回归估计标准误差和相对误差分别为7.59%和0.189 4;单位面积产量与最高处理温度和最高温度持续时间构建模型模拟效果最好,回归估计标准误差和相对误差分别为274.02 g·m-2和0.073%。研究认为随高温胁迫强度加剧、胁迫时间延长,小白菜产量降低,口感变差,营养物质含量减少,说明高温胁迫使小白菜品质变差。

Effect of high-temperature on the quality of pakchoi and its simulation

To explore the effects of high-temperature stress on yield and quality of greenhouse pakchoi, a study was con-ducted from October 2015 to May 2016. In the study, we set three gradients of daytime/nighttime temperatures of 32℃/ 22℃, 35℃/25℃, 38℃/28℃, with 25℃/18℃ as the control, and the duration of each treatment was 3 d, 6 d, 9 d and 12 d, respectively. The results showed that: (1) the dry weight, fresh weight, leaf fresh weight, leaf length, leaf width, petiole width, SPAD and per unit area yield decreased with increased high-temperature stress. Furthermore, the decline aggravated with in-creasing treatment duration. (2) Petiole length and rolled leaf rate increased gradually with increased temperature and duration. High-temperature stress increased the content of crude fiber. Under short-term high-temperature stress condition, the contents of soluble sugar, soluble protein and vitamin C did not change obviously, but gradually decreased due to increased temperature degree and stress duration. (3) A mathematical model of rolled leaf rate and per unit area yield of pakchoi was established and vali-dated by independent experimental data. The root mean square error and relative error of model of rolled leaf rate with minimum temperature and treatment time were small — respectively 7.59% and 0.1894. The model for yield per unit area with maximum temperature and treatment time were smaller — also respectively 274.02 g·m-2 and 0.073%. Our study suggests that high-temperature stress downgraded pakchoi appearance quality and internal quality with increasing stress time and degree. Besides, we defined high-temperature stress index and determined high-temperature stress degree for greenhouse pakchoi. The results provided scientific basis for the determination of meteorological indicators and for disaster prevention.