钾对不同基因型玉米生长、体内钾循环和分配的影响

钾素循环和再利用对维持植物生长和提高钾利用效率非常重要。本文以杂交玉米豫玉23和兴农998为供试作物，采用供应高钾（1.85 mmol/L）和低钾（0.1 mmol/L）营养液的石英砂培养方法，研究不同基因型玉米各器官干重和钾积累及分配、 体内钾在木质部和韧皮部中的循环、 流动及钾效率等。结果表明，低钾处理10 d后，与高钾处理相比，低钾降低两玉米品种各器官干重净增量、 钾浓度、 钾积累量、 钾吸收效率和木质部中钾的运输量，增加钾利用效率和源叶中韧皮部输出的钾，提高钾通过韧皮部的再循环量及占木质部运输总量的比例。低钾处理的豫玉23和兴农998上部叶均为钾库，钾积累量的38.5%和70.3%是由各自中、 下部叶韧皮部输出的钾供给，但体内光合产物和钾向上部叶的运输是不完全同步的过程。两品种比较，低钾处理下的豫玉23较兴农998干重净增量提高，在于前者具有较大根量、 较高钾吸收速率和较多钾素吸收量，木质部中有更多的钾通过叶片韧皮部输出进行循环运输进入上部叶；但豫玉23对介质中钾的吸收大于体内钾的再利用。钾营养高效基因型玉米应该具有较强的吸收和利用体内钾的能力。

Effects of potassium on plant growth, potassium cycle and distribution in different maize genotypes

Potassium (K) cycling and recycling are important for maintaining plant growth and enhancing K use efficiency. Two maize (Zea Mays L.) hybrids,yuyu 23 and xingnong 998, were used as the testing materials. Two K levels, high (1.85 mmol/L) and low (0.1 mmol/L) were set up under the conditions of sand and nutrient culture. Dry weight, K accumulation and distribution in each organ of maize, K cycling and flowing between xylem and phloem, K uptake and use efficiency were studied. The results show that during the ten days after the high and low K applications, compare with the high K treatment, the dry weight, K concentration and accumulation in each plant organ, K uptake efficiency and transported amount in the xylem under the low K treatment are decreased, while the K use efficiency and retranslocated amount from leaves by phloem are increased. At the same time, the K recycling from lower leaves to roots through phloem is activated under the low K condition, and then transported to the upper leaves via xylem. The upper leaves of two maize cultivars are the K sink in the low K treatment, 38.5% and 70.3% of K are provided by phloem of the middle and lower leaves, but their assimilation is not synchronized with K transportation to the upper leaves. In the low K treatment, the dry weight increment of yuyu23 is higher than that of xingnong 998, because the cultivar of yuyu23 has larger root dry weight, greater K uptake efficiency and accumulation, more proportion K from xylem transported into the upper leaves, and the K uptake capacity of yuyu23 is stronger than the K use in whole plant. High K nutrient genotype of maize should have greater K uptake and use capacities.