| Tall fescue (Fectuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.) were two of the most common cool-season turfgrass species, with long green period and pleasure landscape. However, almost all cultivars used in China were released from the USA. Those cultivars were hard to adapt to the weather conditions with high temperature and high humidity during the summer in the Yangtze area. Although a few local cultivars were released in China, few of them can be used in urban landscape widely because of the limitations in seed production. This study was focused on tall fescue and Kentucky bluegrass in following five experiments: 1) observation of spike differentiation and blooming behavior of tall fescue and Kentucky bluegrass; 2) effect of different level of nitrogenous fertilizer on seed yield and yield components in tall fescue and Kentucky bluegrass; 3) effect of different density level on seed yield and yield components in tall fescue and Kentucky bluegrass; 4) adaptation observations of different cultivars and lines of tall fescue and Kentucky bluegrass in Shanghai area; 5) summer management of cool-season turf. The results were as follows:1. The processes of spike differentiation in tall fescue and Kentucky bluegrass are basically the same. The whole process of spike differentiation could be divided into five stages, which are: the differentiation stage of bract primordium; the differentiation stage of primary branch primordium; the differentiation stage of secondary and third branches primordia; the differentiation stage of spikelet and floret primordia; the stage of stamen and pistil primordial formation. The differentiation of bract primordium is during spring green-up period, and the primary branch primordium differentiate is during spring green-up period to tillering period. The differentiation of secondary and third branches primordia happens in tillering period, while the differentiation stage of spikelet and floret primordia is during jointing stage. The formation of stamen and pistil primordial happens in booting stage. The order of flower blooming was the same as that of spike differentiation of floret. The flowering order of the braches in the spike was from up to down, but the flowering order of florets in a single spikelet was from down to up; the flowering order of each braches was that the top flower open first and then in bottom-up order. 2. Nitrogen fertilization increased fertile tiller number, seed number per spike and seed weight significantly. The fertile tiller number in tall fescue reached the highest in the middle level of nitrogenous fertilizer treatment (N2, 100kg/hm~2), with 805 and 600 grains per m~2 respectively in two experimental fields, which were significantly higher than other treatments and the control. High level of nitrogen fertilizer (150kg/hm~2) treatment increased the tall fescue tiller number significantly, but the fertile tiller number was significantly lower than the middle nitrogen level treatment, indicating that more infertile tillers produced from excessive nitrogen fertilizer. All nitrogen treatment increased the seed number per spike, but significant differences among the various nitrogen treatments. Three nitrogen fertilization treatments also increased seed weights. The middle nitrogen (100kg/hm~2) treatment reached the highest seed weight with 1.964g and 1.798g in two different experimental fields. Nitrogen fertilization increased the seed yield significantly in tall fescue, and the middle nitrogen level treatmment reached the highest seed yield with 2009.5kg/hm~2 and 1185kg/hm~2 in two experimental fields, respectively, which were 125% and 35% of increase when compared with the control.Nitrogen fertilization also had significant effects on seed production in Kentucky bluegrass. The best result occurred in the middle nitrogen level treatment (100kg/hm~2). The fertile tiller number reached 136 and 195 per square meter in two different experimental fields. All nitrogen treatments increased the grain numbers per spike significantly, but no significant differentiation among the three nitrogen levels. The middle nitrogen level treatment (100kg/hm~2) showed the highest seed weights with 0.225g and 0.220g per thousand seeds in two different experimental fields. The middle nitrogen level treatment reached the highest seed yield in Kentucky bluegrass in both experimental fields, with 111.4kg/hm~2 and 148.0kg/hm~2 respectively, which were significantly higher than the control.3. The increase of tall fescue planting density increased the number of fertile tiller. The tiller numbers in the high planting density (D3, 63,000 plants per hm~2) treatment were significantly higher than those of the low density (4.2 plants per hm~2) and the middle density (50,000 plants per hm~2) treatment, and reached 4323 and 3859 tillers /m~2 in the two experimental fields. The high planting density also resulted the higher fertile tiller number than the low and middle planting density treatments, and reached 741 and 614 spikes per m~2. In the east experimental field, there were no significant differences in seed number per spike and seed weight among the various planting density treatments. In the west field, the high planting density treatment resulted in higher seed number per fertile tiller and seed weight than the low and middle density treatments, indicating that there were no negative effects on seed number per fertile tiller and seed weight when increased planting density in tall fescue. The high density treatment also showed the highest seed yields in two experimental fields with 1230.7kg/hm~2 and 1774.1kg/hm~2, respectively. The results indicated that seed yield in tall fescue could be significantly increased by reasonably increasing planting density.Increasing planting density also increased the total tiller number per square meter, but it was not true in the fertile tiller number. In the two seed production fields of 2004 and 2007, the fertile tiller number in high density treatment (D3, 111,000 plants per hm~2) was significantly lower than the low density treatment (D1, 66,000 plants per hm~2), which indicated that the high planting density treatment produced more infertile tillers. There were no significant differences in grain number per spike and seed setting rate among three different density treatments. In the 2007 seed production field, no significant difference was observed among three different density treatments in seed weight. However, in the 2004 field, the middle density treatment (D2, 83,000 plants per hm~2) produced the highest seed weight, which was significantly higher than that the high density treatment (D3), showed the negative effects on nutrition accumulation and seed quality. For seed yield, the low planting density treatment (D1) showed the highest seed yield in both seed production fields, with 116.5 kg/hm~2 and166.4 kg/hm~2 respectively, which were significantly higher than the high density treatment (D3). The results indicated that the control of planting density was critical in Kentucky bluegrass seed production. The high seed yield and good seed quality should be resulted from reasonable planting density and improved growth conditions during reproduction stages.4. The field evaluation experiment in yearly turf performance and summer disease occurrence with 22 tall fescue cultivars or lines and 26 Kentucky bluegrass cultivars or lines showed that tall fescue cultivar'Triple A', and Kentucky bluegrass cultivar'KB6'performed better turf quality and less diseases incidence compared with other cultivars and lines in Shanghai. The results indicated that these two cultivars/lines can be used more widely in urban landscape.5. A new tall fescue selection T6 showed better performance in turf density and vertical growth than the control cultivar Barlexas thoughout the summer in field plot experiment. The results suggests T6 maybe a good tall fescue for the Yangtze area after further observation and study. The mixture of tall fescue and Kentucky bluegrass turf showed the better disease resistance than the single tall fescue turf during the summer, which increased the turf performance in summer. Disease resistance index in tall fescue was significantly negative related to the soil temperature and canopy temperature based on the investigations of three different turf environments. The higher soil temperature and canopy temperature, the lower disease resistance index and the more summer diseases occurred in the turf. The results indicated that the decrease of disease incidence in tall fescue could be achieved by mixing with Kentucky bluegrass and decreasing the soil temperature.
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