基于营养动态积累的普通白菜最佳采收期综合评价

Studies on Comprehensive Evaluation of Optimal Harvest Time of Brassica campestris L.ssp.Chinese Baby Greens Based on Nutrient Accumulation Dynamic

普通白菜(Brassica campestris L.ssp.Chinese)的苗菜—鸡毛菜生产中的采收期确定仍以传统的经济产量为主,而忽略了品质。本试验以普通白菜品种华王为试验材料,使用72、128、200、288孔4种穴盘规格,于播种后5、8、11、14 d和17 d采样,研究不同规格穴盘栽培普通白菜苗菜的生理形态与营养品质变化规律;并采用主成分分析法筛选出普通白菜综合品质的重要指标,提出“采收指数”这一指标对普通白菜的苗菜综合品质进行评价,以期在保证产量的前提下以营养品质来确定最佳采收期。结果表明:不同规格穴盘普通白菜形态的变化趋势较好地拟合二次多项式函数。随着播种后时间的延长,VC含量整体呈增加趋势;可溶性蛋白含量在播种后14 d达到最大值;硝酸盐含量前期高,在大幅度降低后小幅度回升;72、128、200孔穴盘普通白菜总叶绿素和类胡萝卜素含量在播种后14 d增长至最大值,而288孔穴盘普通白菜总叶绿素和类胡萝卜素含量在播种后5~17 d变化不大。主成分分析共提取4个主成分,累积方差贡献率为72.244%。各规格穴盘普通白菜采收指数均在播种后14 d达到最大值,由大到小顺序为288孔>200孔>128孔>72孔。至播种后17 d,288、200孔和72孔穴盘采收指数均大幅下降,而128孔穴盘普通白菜的采收指数下降幅度较小。因此,在本试验的5个采收时期中,上海地区春季玻璃温室穴盘生产普通白菜苗菜的最佳采收期为播种后14 d,其中288、200孔穴盘的采收期不宜延迟,而128孔穴盘可适当延迟至播种后17 d。

The harvesting time of baby greens of pakchoi(Brassica campestris L.ssp.Chinese)is mainly determined by traditional economic yield and its quality was neglected.Taking pakchoi variety‘Huawang’as test material,this experiment designed 4 plug cell sizes,including 72-cell,128-cell,200-cell,and 288-cell,and conducted sampling 5,8,11,14,17 days after sowing(DAS).Then,the variation rule of physiological morphology and nutritional quality of the baby greens cultured in plug cells with different sizes were studied.Principal component analysis was used to screen out the important indicators for comprehensive quality of the baby greens.“Harvest index”was put forward to evaluate the comprehensive quality of baby greens,hoping on the premise of guaranteeing the yield to determine the best harvesting time by nutritional quality.The result indicated that the morphological variation trend of baby greens under different plug tray were better matched with quadratic polynomial function.The VC content presented increasing trend along with the time extending after sowing.The soluble protein content reached the maximum value on 14 DAS.In earlier stage the nitrate content was high,then increased slightly after a significant reduction.The contents of total chlorophyll and carotenoid under 72-cell,128-cell and 200-cell plug tray increased to the maximum value on 14 DAS.While,those under 288-cell plug tray had no big changes on 5-17 DAS.Principal component analysis extracted 4 principal components,and the cumulative variances contribution rate reached 72.244%.The value of harvest index of baby greens under all sizes of plug trays reached maximum value on 14 DAS.The value order from big to small was 288-cell>200-cell>128-cell>72-cell.The harvest indexes of 288-cell,200-cell and 72-cell all decreased substantially until 17 DAS.While,the harvest index of 128-cell decrease with smaller margin.Therefore,during the 5 harvesting stages investigated in this study,the best harvesting period for the production of baby greens in glass greenhouse in spring in Shanghai region was 14 DAS,among them the harvesting time of 288-cell and 200-cell plug trays was not suitable to delay.While,the 128-cell plug tray could be properly delayed to 17 DAS.