| Italian ryegrass (Lolium mulitiflorum) is one of the most important warm season forage grasses which has high yield, good nutrition and palatability, and has been widely used in animal husbandry. With the increasing of cultivated area the requirement for its seed production is increasing. But lodging of Italian ryegrass during filling period is serious in its principal producing area--coastal area of Jiangsu province, which not only reduces seed yield but also hinders mechanical harvest. In this study three growth regulators were used at jointing stage to modify plant growth, and observe the effect of growth regulator on the growth and seed yield of Italian ryegrass. The concentration of trinexapac-ethyl were141,282,423and564g/hm2, Paclobutrazol50,100,200,400g/hm2, Maize roborant0.855,1.71,2.56,3.42L/hm2, respectively. The sowing rate were1.5,3.0,6.0kg/hm2respectively.After trinexapac-ethyl treatment, the plant height became lower, internode length reduced, stomatal opening, the chlorophyll content increased, with the increasing of concentration, the promote effect of Trinexapac-ethyl enhanced. Trinexapac-ethyl application effectively decreased lodging rate of Italian ryegrass. The inhibition rate of plant height was15%and there was no plant lodging with564g/hm2application. Trinexapac-ethyl could shorten spike length, and increase kernel number per spike and spike number per plant significantly. With the application rate of Trinexapac-ethyl increasing, seed yield increased and lodging reduced, when the concentration was564g/hm" seed yield began to decline. Treated with423g/hm2can effectively prevent plant lodging, increase the number of kernel number and seed yield.Paclobutrazol treatment can promote plant tillering, increase effective panicles. The effect on plant growth increased with the concentration. When treated with400g/hm2, effective panicle has been increased by42%compared with control. However. the duration of paclobutrazol effect was short. With increase application time, culm length of Italian ryegrass became shorter and stem diameter of the second section increased. With increasing of concentration the effect was enhanced.Maize roborant treatment can effectively increase the effective panicles and prevent lodging within low concentration at unit area. When the Maize roborant dose was 1.71L/hm2, the seed yield was up to7353.90kg/hm2increased by41.4%which was the highest seed yield in all treatment of Maize roborant. When the concentration was up to2.56L/hm2Maize roborant would make seed abortive and reduced seed production.Under different sowing conditions the same concentration of growth regulator has different effect on plant growth and seed yield. The effect of growth regulator decreased with increasing of sowing rate. Paclobutrazol at400g/hm2has beeter effect on the growth of Italian ryegrass under three sowing rate, and the best treatment combination was S3P400, whose seed yield was7872.10kg/hm2, increased by44%compared with the control. For Trinexapac-ethyl, its good combinations were S3P400, S3T423, S6T564, and S6T564has the highest, and its seedyield was8060.80kg/hm2, which increased by33%compared with the control.The results indicated that growth regulator could suppressed culm length, decreased the center of gravity of plant and increase the number of vascular bundles in stem, which might be the reason why the plant growth regulator could effectively prevent plant lodging. After the treatment of Trinexapac-ethyl, the lodging decreased and seed yield of Italian ryegrass was higher than Paclobutrazol and Maize roborant, and it was up to7399.5kg/hm2, increased42%compared with control. The actual yield of experimental plot is2.47-3.16kg, which as the theory of production by28%-36%, under the condition of3sowing rate, the area of each plot was12m2. |
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