Study On Influence Of Applying Plant Growth Retardants On Growth Of Turfgrass

A lot of researches had indicated that plant growth retardants (PGRs) can influence the overground growth of turfgrass intensively. The rate of stalk and foliage slows down if PGRs are applied, so the height of plant was depressible. Therefore, experiments of researches were conducted in The Teathching and Demonstration Farm of Agricultural University of Hebei. Three types of PGRs which were applied on turfgrass manufactured by American researchers were used in this experiment. Trade names are Primo Trimmit and Proxy. And it was the first time that the three types of PGRs were applied under Chinese climate and entironment. And at meantime, contrast experiments with two types familiar Chinese PGRs (Paclobutrazol and Ethephon) of the impact were put up, and the experiments included potted plant ones and field ones. And also the regreening growth of potted plant kentucky bluegrass (Poa pratensis) and tall fescue {Festuca arundinaces) which were dealed with the three new types PGRs last year were observed and noted. The main results summarized as follows:1. In spring and autumn, Primo could stay the height of plant both on kentucky bluegrass and tall fescue, and the exhibition of middle and high concentrations were better, and the high ones was the best. But there were also differences in two different kinds of turfgrass. For example, in kentucky bluegrass the staying impact of Primo could last 30~40 days in spring, while about 55 days in autumn, and in tall fescue about 40 days in spring, while about 55 days in autumn. Trimmit had no staying impact in both on kentucky bluegrass and tall fescue. Proxy represent the strong staying impact in kentucky bluegrass lasting 45~55 days in spring and about 50 days in autumn, but it had no staying impact in tall fescue.2. Primo could reduce the clipping of kentucky bluegrass and tall fescue intensively, and the treatment of high concentrations was the best one. In a certain extent the clipping also could be reduced by Proxy, but it had no influence in the clipping of tall fescue. Trimmit had no influence in the clipping of both kentucky bluegrass and tall fescue. The contrast between Primo and Proxy was that Primo had the best influence in the prophase of experiment and Proxy had the best one in the anaphase.3. As for kentucky bluegrass, from regreening to 30 days, those treatments of different retardants and different concentrations both reduced the clipping in different extent compare with CK. And then most of the treatments started to grow at higher speed in different extent except Proxy, and had similar clipping of CK gradually. While the clipping of the high concentration treatment was intensively lower than CK until 90 daysafter regreening. Those treatments of different retardants and different concentrations had no influence in the growth of tall fescue.4. Compare with the tow types of retardants which often were used in crop field in China (Paclobutrazol and Ethephon), Primo could reduce the height of the plant intensively, and the impact could last 35 days. The impact of Proxy could last about 45 days, while the impact of Paclobutrazol could last 40-45 days, but the impact of Ethephon could only last about 20 days. As for clipping, it was intensively reduced in 40 days after applying Primo on turf. And the clipping of the treatment by Proxy was less at 20th, 40th and 60th day. The low and high concentrations of Paclobutrazol both could stay the growth. While the staying impact of Ethephon could only last 15 days. The main result summarized as: Paclobutrazol >Proxy>Primo>Ethephon.5. The impact of Primo could last about 50 days on mixed seeding turf of tall fescue and ryegrass, and the impact of Proxy, Paclobutrazol and Ethephon both could last about 35 days;While The impact of Primo could last about 28 days on mixed seeding turf of kentucky bluegrass and ryegrass. The impact of Proxy could only last about 7 days, but The impact of Paclobutrazol could last about 21 days. But the height of plant of these treatments was similar with CK when the experiment was finished. As for the treatment of Ethephon had no influence on mixed seeding turf of tall fescue and ryegrass.6. The clipping of the mixed seeding turf of tall fescue and ryegrass was reduced by Primo, and the influence was stable.Proxy and Ethephon could reduce the clipping in the prophase. While Paclobutrazol could do this after 14 days applying it. But the clipping of plant of these treatments was similar with CK when the experiment was finished;Applying Primo, Proxy and Paclobutrazol could reduce the clipping of mixed seeding turf of kentucky bluegrass and ryegrass quickly and intensively, and Paclobutrazol was the best one, it could last about 28 days. While Ethephon could do this after 28 days applying it, and it could only last about 14 days. The clipping of plant of these treatments was similar with CK when the experiment was finished.7. The content of chlorophyll a, chlorophyll b and chlorophyll a+b of kentucky bluegrass was not be affected in all different treatments at different periods.8. Leaf moisture content of the mixed seeding turf of tall fescue and ryegrass and kentucky bluegrass and ryegrass was not be affected in all different treatments at different periods.9. In the investigation, all different treatments had less spikes than CK intensively, and the treatments of Primo and Paclobutrazol were the best ones.