| The experiment was conducted at the experimental farm of Shandong Agricultural University during 2001 and 2002. In the first year, six varieties were selected and their changes of yield and difference of quality were compared in field high temperature conditions. On the basis of that, Nongda108 (which represents the type of better adaptation to high temperature) and Shangnong3 (which represents the type of poor adaptation to high temperature) were selected in that basis. Effect of high temperature on yield and quality of maize and their physiological and biological principle was studied systematically; at the same time regulations were researched. The principal results were as follows:1. Effect of high temperature on yield in maize Yield of maize was decreased by high temperature during the whole growth stage, and yields of all the variety were lower than their CK. Different high temperature phases had different effect on yield. High temperature in the first phase (0~28 days after emergence) had no evident effect on yield. In the second phase (29~62 days after emergence ) and the third phase (63~92 days after emergence), yield was decreased by 23.76% and 17.83% respectively. The effect of high temperature in the second period was the most . Different varieties had different response to high temperature. After high temperature, yield of Nongda 108 decreased by 10.75%, Shannong 3 decreased by 17.37%, high temperature has less effect on the yield of Nongda 108 than that of Shannong 3. The decreased ear kernel weight and the weight of 1000 kernels result in the decreased yield. High temperature shortened the growth duration of maize, made the leaf area reduced , and decreased the accumulation of dry weight and economic coefficient ,which is the direct reason of yield decreasing.2. Effect of high temperature on quality of maize grain High temperature during the whole growth stage decreased the content of starch. The content of protein in Liaoyu 5 and Yedan 2 evidently decreased compared with CK, while The content of protein in Shannong 3,Luyuandan 14 and Ludan 50 rised evidently, Nongda 108 had no obvious change. The content of ether extract in Shannong 3,Liaoyu 5 and Luyuandan 14 rises evidently, while that in Nongda 108,Luda 50,Yedan 2 decreased. The total content of fatty acid in Nongda 108 and Liaoyu 5 was lower than that in CK, while Shannong 3, Yedan 2,Ludan50 and Luyuandan 14 was higher than that in CK.High temperature in different period had effect on quality in maize grain. The content of starch increased in both varieties in first high temperature phase. High temperature in the second and third phase decreased the content of starch in the both variety. The decrease ofstarch content was mainly resulted by the increase of amylopection content. The change of protein content was contrary to that of starch, high temperature in the first phase decreased the content of protein, while high temperature in the second and third period increased the content of protein, and two varieties had the same trend. The changes of all protein components content in ND108 had the same trend with the changes of total protein content. Only the content of albumin and glutelin in Shannong 3 had same changing trend with the total protein content. The effect of high temperature phase on amino acid content and its component was different among varieties. High temperature in the first phase decreased the content of amino acid in Shannong 3, but raised the amino acid content in Nongda108. High temperature in the second phase raised the amino acid content in Shannong 3, but decreased the content of Nongda 108. High temperature in the third phase had no effect on the content of amino acid. High temperature in all three phase made the ether extract content lower than their CK. The extent of decreasing in the first phase is the largest and that in the second period was the least. Two varieties had the same trend.3.Effect of high temperature on the absorption and utilization to nitrogen (N), phosphorus (...
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