钾局部供应对玉米根系生长和钾吸收速率的影响

采用自制培养装置，在玉米种子根的局部根段供应含钾营养液。研究证明钾局部供应不影响地上部和总根系干物质的积累。试验开始后第１０ 天钾局部供应使供钾区的根系总长明显增加，这是由于二次侧根长度和数量的增加，但一次侧根生长增加不明显。试验开始第３ 天起，钾供应区的钾吸收速率明显加快。因此，早期可能主要通过钾吸收速率的加快来补偿由于钾局部供应的不足，二次侧根长出以后，根系生长的增加可能部分补偿供钾的不足。１４ Ｃ示踪试验表明，钾局部供应时，植株中的光合产物运向供钾根区的量多于无钾根区

EFFECTS OF LOCAL SUPPLY OF K ON ROOT GROWTH AND K UPTAKE RATE IN MAIZE

Using a liquid culture system, in which a nutrient solution containing 1 mmol/L K was supplied to a 25 mm or 40 mm segment of the primary root while the remainder of the root system received a K free nutrient solution, effects of a local supply of K on root growth and K uptake rate were studied in maize (Zea mays L.).The results showed that the dry matter accumulation of shoot and total root system was not effected.The total root length in the supplied zone was considerably increased on the tenth day of the experimentaiton, that is due to an increased growth of the second order lateral roots, but the growth of the first order lateral roots was not increased.From the third day on after onset of the experiment the K uptake rate was considerably increased, the authors conclude that the increase of the K uptake rate compensated for the deficiency in K supply in the early period.After the increase of growth of second order lateral roots, the increase of root growth may partly compensate for the deficiency in K supply. 14 C labelling experiment showed that the K supplied zone received more photosynthates from shoot than the K free zones.These photosynthates may provide energy for the increase of the K uptake rate.