| The corn hybrid species of Haiyu4 was used as experiment materials. The dynamics regulations of main physiological parameters were studied in this experiment, in which it was subjected to drought stress at different growth stages, different holard and irrigation before seeding. Determining and analyzing relevant physiological parameters, yield and quality in grains, the study contributed theoretical basis to culture of dry farming and irrigation of sparing water in Southern Spring maize. The main experiment results are as follows.(1) The order of germination capacity at different holard was A5>A4>A3>A2>A1. The order of treatment was 15 (A3B5,holard 20%,irrigation 120m~3/hm~2) > 18 (A4B3,hoIard 20%,irrigation 60m~3/hm~2) and 19 (A4B4,holard 20%,irrigation 90m~3/hm~2) > 23 (A5B3,holard 25%,irrigation 60m~3/hm~2) and 24 (A5B4,holard 25%,irrigation 90m~3/hm~2) > 20 (A4B5,holard 20%,irrigation 120m~3/hm~2) and 25 (A5B5,holard 25%,irrigation 120m~3/hm~2) > 17 (A4B2,holard 20%,irrigation 30m~3/hm~2). The result of variance of analysis showed that the germination capacity of treatment in 15,18,19,23,24,were all higher than 85 percent.15 treatment was best from single direction of germination capacity and 18 and 23 were best both from germination capacity and sparing irrigation ,namely when holard was 20%-25%,irrigation was 60m~3/hm~2.(2) Pn showed single peak curve at different holard and irrigation. It was up to the peak at tasseling in all holard treatments. Pn was higher with the higher holard and varied slowly. NR activity was enhancing gradually in the whole growth stages then decreasing. The peak of NRA was advanced at jointing with the lower holard and it was at silking with the higher holard. CAT activity presented single peak curve and up to the peak at tasseling then decreased gradually, but it altered quickly with the lower holard and diminished slowly with the higher holard. POD activity presented the tendency of increasing-decreasing-increasing and the first peak appeared at seven-leaf to jointing, the second peak appeared at silking to grain and the lowest value emerged at tasseling. The content of MDA presented the tendency of increasing rapidly-decreasing slowly-increasing rapidly.(3) 24(A5B4, holard 25%, irrigation 90m~3/hm~2) was best in single plant yield and 15(A3B5,holard 15%,irrigation 120m~3/hm~2) was excellent not only in grains per corncob but also in hundred-grain weight at different holard and different irrigation.(4) The content of CHl, Pn, NR, SS, SPS, CAT activity was all reduced during drought stress at different growth stages. CHla decreased rapidly at booting drought stress, CHlb decreased quickly at jointing drought stress, total CHl was the same as CHla and the peak value presented at silking both in CK and drought stress. During drought stress at different growth stages, theaffected order of Pn was booting>jointing>silking>grain>ripening>seedling; the affected order of NRA was tasseling>booting>jointing>silking>grain>seedling>ripening; the affected order of CAT activity was silking>grain>tasseling>booting>jointing>seedling>ripening. SS and SPS activity were affected markedly at jointing, tasseling and booting. POD activity was affected markedly at tasseling and silking. The content of MDA increased during drought stress at different growth stages.(5)The height, length of leaves, width of leaves, fresh weight of single plant, fry matter weight of single plant, leaf areas of single plant, LAI, yield of single plant and yield components were reduced during drought stress at different growth stages. The decreased percent was the most great to grains per corncob at tasseling drought stress; hundred-grain-weight, at grain stage drought stress; yield of single plant, at booting-blossoming, and the extent was 58.73%-75.41%.(6) The quality of grain was changed during drought stress at different growth stages. The content of sucrose was reduced and percent of protein was increased.
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