氮素形态及配比对甘蓝养分吸收、产量以及品质的影响

采用田间试验,研究了氮素形态及配比对春茬甘蓝生长、光合作用、养分吸收利用、品质和产量的影响。结果表明,NH₄⁺-N和NO₃^--N∶NH₄⁺-N为3∶7处理明显促进甘蓝茎粗的增加;叶片发生数则以NH₄⁺-N处理下相对较多。铵态氮有利于促进甘蓝不同器官中氮含量的提高,硝态氮有利于钾含量的提高,但磷含量受氮源的影响变化不一致。NO₃^--N∶NH₄⁺-N处于3∶7～7∶3范围内有利于提高甘蓝外叶、叶球和根系的氮、磷和钾含量,同时提高甘蓝叶片的光合作用。NO₃^--N与NH₄⁺-N配施处理的增产率显著大于单一氮肥形态的处理,其中NO₃^--N∶NH₄⁺-N处于3∶7～5∶5范围内时促进增产的效果较好,比率为5∶5时最佳。单施NO₃^--N易增加甘蓝叶球硝酸盐含量,减少Vc含量;NO₃^--N∶NH₄⁺-N处于3∶7～7∶3范围内可降低硝酸盐含量,获得较高的可溶性糖含量,其中以NO₃^--N∶NH₄⁺-N为5∶5时效果最好;铵态氮肥(包括酰胺态氮肥)有利于甘蓝叶片中Vc含量的提高。总之,与单一氮肥形态相比,当NO₃^--N∶NH₄⁺-N处于3∶7～7∶3范围内时甘蓝易获得高产和较好的品质,其中NO₃^--N∶NH₄⁺-N为5∶5是最佳比例。

Effects of different nitrogen forms on nutrient uptake,yield formation and quality of cabbage

This study determined the effects of different nitrogen forms on nutrient uptake,yield formation, and quality of spring cabbage (Brassica oleracea var. capitata). A field experiment was conducted at Yuzhong (104°12′ E, 35°85′ N), China in 2012, where eight different N forms and various ratios of different N forms were applied to the crop in a completely randomized block design with three replicates. The results showed that the application of NO₃^--N∶NH₄⁺-N in 3∶7 was conducive to the improvement of the stem diameter of cabbage. The fertilization with single NH₄⁺-N could increase the numbers of leaves. The use of NH₄⁺-N improved the content of N and use of NO₃^--N improved the content of K, but the P content varied with N sources in different organs of cabbage. Cabbage supplied with the ratios of NO₃^--N∶NH₄⁺-N ranging from 3∶7 to 7∶3 was conducive to improve the contents of nitrogen, phosphorus and potassium in leaves, head and roots of cabbage, and could improve photosynthesis of leaves. Compared with single nitrogen fertilizer forms, the combined application of NH₄⁺-N and NO₃^--N could obviously improve the yield of cabbage. The application of NO₃^--N: NH₄⁺-N ranging from 3∶7 to 5∶5 had the better effect on increasing yield, and the ratio of NO₃^--N∶NH₄⁺-N 5∶5 was the best. The fertilization with single NO₃^--N increased the accumulation of nitrate, and reduced Vc content in cabbage. Cabbage supplied with the ratios of NO₃^--N∶NH₄⁺-N ranging from 3∶7 to 7∶3 reduced the accumulation of nitrate and increased the content of soluble sugars, and the application of NO₃^--N∶NH₄⁺-N in 5∶5 had the best results. The application of (NH₂)₂CO-N or NH₄⁺-N was conducive to the improvement of Vc content in the leaves of cabbage. We concluded that the ratios of NO₃^--N∶NH₄⁺-N ranging from 3∶7 to 7∶3 significantly improved the yield and quality of cabbage, and the application of NO₃^--N∶NH₄⁺-N in 5∶5 had best effect.