Response Of Different Maturity Corn Hybrids To Sowing Date And Planting Density In The Semi-humid Region Of Jilin Province

Corn (zea mays L.) hybrids commonly grown in the semi-humid region of Jilin provincecharacterized by rain-fed often encounter spring drought stress, which impairs yield stability. Researchwas conducted at Lishu, near Siping city, from2009through2010to determine the effects of hybridmaturity, sowing date, and planting density on the yield of dryland corn. Short-season hybridJidan27(H1), mid-season hybrid Xianyu335(H2), and full-season hybrid Zhengdan958(H3) that werewidely used in Jilin province and Northeast China spring maize production were planted in early May(D1) and mid-May(D2) of each year and thinned to populations of52500(low, P1),67500(medium, P2),and82500(high, P3) plants ha-1. The main results were as follows.Days from emergence to silking for all hybrids decreased when sowing was delayed. Days fromsilking to physiological maturity decreased for H1, and decreased in2009, and increased in2010for H2respectively, and increased for H3at the later sowing. Days from emergence to physiological maturitydecreased for both H1and H2, but varied not much for H3at the delayed sowing. Difference of cyclelength among hybrid maturities mainly resulted from the difference of days from silking tophysiological maturity among hybrid maturities.D2produced more grain than did D1for H1and for H2at the higher densities; but for H3, D1hadgreater grain yield than D2. Grain yield for H1increased with the planting density increased; grain yieldfor H2decreased as the planting density increased at the D1treatment, but at the D2treatment, thehighest yield of H2occurred at the planting density of P2; grain yield difference for H3among plantingdensities affected greatly by yearly environmental conditions at D1treatment, and the highest grainyield occurred at the planting density of P2at the D2treatment. Difference of greatest yield for eachhybrid maturity between years existed. In2009, the greatest grain yield for H1occurred at the treatmentcombination of P3and D2, and at the treatment combination of P2and D2for H2, and at the treatmentcombination of P2and D1for H3. In2010, the greatest grain yield for H1also occurred at the treatmentcombination of P3and D2, and at the treatment combination of P1and D1both for H2and H3.Kernel weight per ear (KWPE) was greater for H2when compared with H1and H3, and theKWPE of H1was almost equal to that of H3. Generally, H2had the greatest kernel number per ear(KNPE) among hybrid maturities, and H1had the least, although KNPE difference among hybridmaturities varied greatly with the combination of different years, sowing dates, and planting densities.Regardless of sowing date and planting density, H1had the highest100grain weight, and the100-grainweight of H2was nearly equal to that of H3. Grain yield difference among treatment combinationsmainly resulted from biomass yield difference, but it was also related with harvest index. Interestingly,difference of grain volume m-2was consistent with the yield difference among different treatments,which indicated that grain sink per unit land area was crucial for the grain yield determination. Theresult also indicated that the relationship between grain volume m-2and grain yield was closer whencompared with the widely accepted parameter of grain number m-2and grain yield. In conclusion, the results of this study suggested that it should be a feasible way to attain theproduction goal of corn yield stability and drought resistance by using shorter season hybrid withdelayed sowing and increasing plant population in semi-humid region of Jilin province.