* Renesas jumps 31 percent, govt mulls rescue * Defensives in demand, global growth still a concern By Dominic Lau TOKYO, Sept 24 (Reuters) - The Nikkei share average fell to a one-week closing low on Monday as a firmer yen added to woes for automakers and other exporters, which have been under pressure from growing tension between Japan and China. Concerns about global growth weighed on the market even though major central banks have launched fresh stimulus measures to bolster their economies. Some analysts now worry that the new round of stimulus from the Federal Reserve suggests that the U.S. economy is in worse shape than many had feared. Struggling chipmaker Renesas Electronics Corp jumped 31 percent after two sources said a Japanese government fund was part of a consortium including Toyota Motor Corp considering a bailout of the company, countering a bid by private equity firm KKR. The Nikkei eased 0.5 percent to 9,069.29 points , supported by the 200-day moving average at 9,016.86, while the Nikkei China 50, made up of Japanese firms with heavy exposure to the world's second largest economy, shed 1.3 percent. "People are rather cautious," a trader at a foreign bank said. "There is a lot of media coverage on the China-Japan dispute. That's also playing into it." "In 2005 (when the last major dispute erupted), the sell-off actually came in the second week, not the first week. People are just worried about history repeating itself and this thing seems a little bit more serious," he said. Among exporters, Canon Inc sagged 3.9 percent, while Nissan Motor Co, which traders said earns about 25 percent of its net profit from China, ahead of Honda Motor Co's 16 percent and Toyota's 21 percent, dropped 2.7 percent. Toyota lost 1.6 percent and Honda shed 1.8 percent. The yen was trading at 78.060 yen to the dollar on Monday, up from Friday's low of 78.379. Bank of America Merrill Lynch said Japanese carmakers saw a 90 percent drop in showroom traffic and a 60 percent fall in sales in the southern Chinese province of Guangdong, the largest market for Japanese brands, since the start of the anti-Japanese protests. "Dealers believe the current negative sentiment on Japanese-branded cars could be longer than the previous island dispute, as Japanese-branded cars' promotional campaigns and TV commercials have been temporarily suspended," the brokerage said in a note. "Some customers are being instructed not to buy Japanese cars to avoid some difficulties - e.g. some gasoline stands are refusing to supply fuel to Japanese-branded vehicles." Construction machinery makers Komatsu Ltd and Hitachi Construction Machinery Co Ltd fell 1.6 and 1.2 percent, respectively after U.S. rival Caterpillar Inc's reported a 13 percent sales increase for the June-through-August period, slightly down from the 14 percent increase for the May-through-July period. Both Komatsu and Hitachi Construction Machinery, which have significant exposure to China, have fallen at least 11.3 percent since Aug. 20 on concerns of slowing growth in China. Hidehiro Tomioka, head of equity investment at Manulife Asset Management in Tokyo, said the impact of the China-Japan row would depend on how long it would last. "If it were to continue, say, a couple of months, or longer, six months for instance, I think the impact to the macro economy and corporate earnings will not be small," he said. "Right now I am slightly cautious. I would stay away from very highly affected areas like airlines for instance. For the others, I am watching the development." DEFENSIVES SWITCHING However, investors switched into defensive stocks, which have a relatively lower correlation to the health of the global economy, supporting the market. The utilities sector rose 1.2 percent and the telecommunications sector gained 0.8 percent. "Nine thousand is a reasonably important technical level. Our flow today is defensive ... beta (cyclical stocks which tend to have high beta, or volatility) adjust is pretty heavy to the sellside," another trader said. The broader Topix index slipped 0.4 percent to 753.68, with 1.41 billion shares changing hands, down f rom last week's average of 1.85 billion. The Nikkei is up 7.3 percent so far this year, underperforming a 16.1 percent rise in the U.S. S&P 500 and a 12.8 percent gain in the pan-European STOXX Europe 600 index. Japanese equities now have a similar valuation to European shares, with a 12-month forward price-to-earnings ratio of 11.1, versus STOXX Europe 600's 11 and S&P 500's 12.9, according to Thomson Reuters Datastream.