氮肥形态及配比对花椰菜生长和光合特性的影响

Effects of nitrogen forms and proportion on growth and photosynthesis of broccoli

以春茬花椰菜为试验材料,研究了氮肥形态及配比对其干物质积累、根系生长、叶片光合色素含量以及光合作用的影响.结果表明:与单一氮源相比,硝态氮肥与铵态氮肥混合施用更有利于花椰菜干物质量的积累;硝态氮肥与铵态氮肥相比,前者有利于植株根的伸长,后者有利于根的加粗,而两者配合施用更有利于植株根系生长;NO3--N∶NH4+-N=3∶7～5∶5时花椰菜叶片叶绿素含量较高,净光合速率显著高于其它处理;单一氮源、NO3--N∶NH4+-N=7∶3处理时的光合速率均下降,其中,铵态氮处理光合速率降低的原因主要是非气孔因素,而其它处理主要是气孔因素.因此,硝态氮肥与铵态氮肥以3∶7～5∶5配施比单一形态氮肥更有利于花椰菜的生长和干物质积累,提高叶绿素含量和净光合速率.

This study determined the effects of nitrogen forms （（NH2）2CO-N, NO3--N, NH4＋-N, NO3 -NH4 ＋） on dry matter accumulation, root growth,leaves photosynthetic pigment content and photo- synthesis of cauliflower （Brassica o＆racea ）. The results showed that the fertilization with NO3--N mixed with NH4 ＋-N increased the accumulation of dry matter and root growth. Supplied with NO3--N promoted root elongation growth, with NH4 ＋-N conducted root bold. The ratios of NO3--N： NH4 ＋-N ranging from 3 ：7 to 5：5 significantly improved chlorophyll content and Pn compared with （NH2）2 CO-N, NO3 -N, NH4 ＋- N. The reduction in net photosynthesis rate was considered to be a result of stomatal restriction mainly in leaves under NH4 ＋-N treatment,while the reduction in net photosynthesis rate was considered to be a result of non-stomatal restriction mainly in leaves under other treatment. It is suggested that the combined application of NO3--N and NH4 ＋-N in an appropriate ratio should improve growth, dry matter accumulation, chlorophyll content and Pn of broccoli.