| The experiment was conducted at the Research Institute for Agriculture of Heilongjiang BaYi agricultural university, at Mishan City, Heilongjiang Province,in 2008-2009 . We selected two spring wheat varieties, Longmai 26 and Kehan 16 as experimental materials, using randomized block design of experiment, and studied the effects on yield and quality of different wheat sowing dates and planting density. Furthermore, we investigated the favorite composition of sowing date and planting density for spring wheat in Heilongjiang Province for the sake of supplying theory evidence for the practice of wheat production. The major results are as follows:1,Sowing date and density have regulated the yield, plant height and stem diameter of Longmai 26 and kehan16 effectively and significantly. Under the conditions of early sowing and moderate density, the yield of two varieties was improved significantly, as well as yield components. However, the later sowing date and the high-density disadvanaged the increase of 1000-grain weight, but the spike number can be increased and seed setting rate can be reduced, can not be formed big ear. The plant weight and and stem diameter is reduced gradually with the delayed sowing date and decreased significantly with increasing density.2,The sowing date also can affect the grain filling characteristics on Kehan16 and Longmai26 of different degree. The average grain filling rate of kehan16 has a increased trend with the sowing date postponing, showing as that of Late sowing greater more than early sowing, and the maximum emerged at the third sowing date. The Gmax of longmai26 also showed the same trend, but the average filling rate was no significant trend. The filling initial growth potential R0 of two varieties increased first and then decreased with the delay of sowing, but the active growth phase D of early sowing is greater more than late sowing with the sowing delayed. The influnce of density was not significant.3,The chlorophyll content of flag leaf of two varieties in the late sowing and high-density conditions was more lower and the value of Ph, Cond, and Ci are incresed first and decreased afterwards totally but the Tr value increased gradually. However, the fluorescence parameters Fv/F0 and Fv / Fm decreased with the delayed sowing date and increasing density.4,Late sowing and moderate density can improve the content of protein, and decrease content of starch of Longmai 26 and kehan16. Also, late sowing can improve four protein components and grain gluten significantly. When sowing date was delayed, the flour sedimentation value also showed a rising trend, but the volume weight decreased. Late sowing and low-density conditions are beneficial to the improvement of flour formation. but the flour dough stability under early sowing can not be improved. The tensile resistance will decrease with the delay of sowing, medium and high density conditions. And the dough extensibility will be incresed with later sowing.5,Considering the influence of sowing date and density to yield and quality of Longmai26 and Kehan16, we can adjuste the sowing date and density appropriately for different use of wheat. Late sowing will help improve grain protein content, flour formation and extension characteristics, and early sowing can increase yield and starch content and improve flour dough stability and tensile resistance. |
