磷对不同玉米品种生长、体内磷循环和分配的影响

以杂交玉米蠡玉16和冀单28为供试作物，采用供高磷（250 mol/L）和低磷（5 mol/L）营养液的石英砂培养方法，研究2个玉米品种的各器官干重和磷积累与分配、体内磷在木质部和韧皮部中的循环、流动及磷的吸收和利用效率。结果表明，与供高磷处理相比，低磷处理的2个玉米品种各营养器官的干重、磷含量和木质部中运输的磷量显著降低; 而磷在体内韧皮部的再循环显著增加，并且玉米各部位叶片活化出的磷主要是通过韧皮部循环至根中后，再经过木质部向上部新生叶运输的; 体内光合产物与磷向上部叶的运输是不同步的过程。低磷时，与冀单28相比，蠡玉16的根冠比高010，整株干重和磷含量增加269%和120%，磷吸收和利用效率提高121%和133%，木质部总磷向上部叶运输的比例高306%。说明低磷条件下，磷高效玉米品种生物量大是由于具有较大的根冠比，木质部中更大比例的磷被分配到上部新生叶以及其具有较高的磷吸收和利用效率。

Effects of phosphorus on the plant growth, phosphorus cycling and distribution in different maize cultivars

Phosphorus cycling and recycling is important for maintaining plant growth and enhancing P use efficiency. Two maize (Zea Mays L.) hybrids, Liyu 16 and Jidan 28, were used as the testing materials. Two P levels: high (250 mol/L) and low (5 mol/L) was set up under the conditions of sand and nutrient culture. Dry weight and P content in each organ, P cycling and flowing between xylem and phloem, P uptake and use efficiency were studied. The results showed that during the study periods, compared with high P treatments, low P significantly depressed dry weight and P content in each plant organ and P transported in the xylem, while increased P retranslocated from leaves to the root by phloem. P activated in each leaf organ were recycled to roots through phloem, and then transported to the upper new leaves via xylem. Moreover, assimilation was not synchronized with P transportation to upper leaves. Compared to Jidan 28 cultivar, Liyu16 cultivar had higher ratio of root to shoot, dry weight, P content, P uptake efficiency, P use efficiency, P proportion from xylem transported into the upper leaves, accounting for 010, 269%, 120%, 121%, 133% and 306%, respectively under the low P. In conclusion, the biomass of P-high efficiency maize cultivar under the low P was higher which was partially attributed to its higher ratio of root to shoot, more P transported to upper leaves in the xylem, higher P uptake and use efficiency.