| In order to prevent maize lodging and achieve high and stable yields,different genotypes of maize ZD958(compact type)and LY99(semi-compact type)were used to set up planting density and chemical control treatment.The densification and high yield potential of spring maize under chemical control and the physiological mechanism of chemical control of Spring Maize in different ecological areas of Liaoning Province were studied.The effects of chemical control on Yield and yield components of spring maize were discussed from the aspects of plant morphological index,photosynthetic index,key enzyme activity of nitrogen metabolism,stem toughness,yield and ear traits.The aim was to establish chemical regulation for high and stable yield of Spring Maize in different ecological areas of Liaoning Province.The results are as follows:1.The yield performance of ZD958 and LY99 increased first and then decreased with the increase of density in three different ecological areas,and the relationship between yield and density was quadratic curve.The yield of ZD958 was the highest under D3 density in all three ecological areas,while LY99 was the highest under D2 density.Under the same density,the yield of LY99 was higher than that of ZD958.After spraying chemical regulator in Southern and Northern of Liaoning,the yield increasing effect of LY99 is better than that of ZD958,while it is opposite in Western of Liaoning Province.The ear length and grain number per row of ZD958 and LY99 decreased with the increase of density,and the 100-grain weight increased first and then decreased with the increase of density.Spraying chemical regulator optimized yield components,significantly increased ear length,grain number per row and 100-grain weight of two maize hybrids.Comparing the average increasing range of grain number per row and 100-grain weight of the two hybrids in three ecological regions,ZD958 showed the increasing range was 2.43% and 7.63% in Western Liaoning,respectively.The average increasing of grain number per row of LY99 was 1.78% in Northern Liaoning,and the average increasing of 100-grain weight was 3.09% in Western Liaoning.2.The densification of maize population resulted in lodging-sensitive stalks.Chemical regulator treatment dwarfed maize plant height,ear height and made stalks stronger.Under D1-D4 density treatment,the plant height of ZD958 was reduced by 5.05%,2.38%,5.35% and 2.74% respectively,and the ear height was reduced by 11.76%,4.59%,7.18% and 8.81% respectively.The plant height of LY99 decreased by 1.22%-5.32%,while ear height by 2.53%-10.62%.In Tieling area,the lodging rate of ZD958 under D2-D4 density increased significantly with the increase of planting density.Under D4 density,the lodging rate was 9.58%,while under TR treatment,the lodging rate was 2.5%,no lodging occurred under other densities.3.Densification increased leaf area index and premature senescence.Spraying chemical regulator resulted in lower LAI decline in late stage of grain filling,preventing premature senescence of higher density population.The SPAD value of ZD958 increased by 3.26%,5.50% and 5.08% respectively in Southern Liaoning,Western Liaoning and Northern Liaoning,while LY99 increased by 3.97%,2.45% and 4.26% respectively at filling stage.4.The activities of SOD and POD in the leaves of the two hybrids showed a single peak curve within 0-40 days after anthesis,and the peak values appeared at 20 days after anthesis.Under the condition of high density D4,the activities of SOD and POD of the two hybrids were better than those of the control after spraying chemical regulator,and the decreasing extent of SOD activity was lower than that of the control 20 days after anthesis.The results showed that spraying chemical regulator could enhance the activities of SOD and POD,effectively regulate the tolerance of maize,and reduce the senescence rate of maize leaves at the late filling stage.Spraying chemical regulator inhibited MDA content and delayed leaf senescence at late filling stage.Under D1-D4 condition,MDA content in leaves of LY99 treated with TR decreased by 2.15%,27.75%,20.55% and 22.69% respectively,with an average decreasement of 18.28%,which was higher than that of ZD958.5.NR activity of ZD958 and LY99 increased first and then decreased with the increase of density.NR activity of ZD958 increased by 6.33%-11.44%,while LY99 by 4.28%-11.59% 20 days after anthesis.GS activity of ZD958 increased by 1.95%-23.14%,while LY99 increased by 3.25%-15.45% at 20 days after anthesis.Spraying chemical regulator significantly increased the activities of NR and GS,promoted nitrogen assimilation and metabolism,increased chlorophyll content in Maize leaves,maintained normal metabolism in maize,and delayed leaf senescence in late stage. |
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