Climate Adaptability Of Hybrid Maize Planting In Northeast Of China

Object:As the basic conditions on agricultural production, meteorological factors mainly effect maize yield besides hybrids, soil and cultivation measures. Better understanding the climate adaptability not only helps selecting and popularizing maize hybrid at certain region, it can fully exert maize hybrids' potential productivity also. Matching thermal resource with hybrids characteristics can fully use the thermal resources; reducing the risk of bad weather conditions; increasing the maize yield per unit area and total yield in northeast China.Methods:In this paper, field experiments were conducted in 2007 to 2009 at the Dongbei Plain, northeast China (lat.40°N to 48°N), where spring maize were largely planted. Maize hybrid which named Zhengdan958 was planted in 28 sites to observe its ecological adaptability, compared to the local cultivars. Combine with the historic meteorological data, the hybrid's yield and yield potential, growing days and accumulated temperature needed to mature were studied. Based on different maize characteristic need different thermal resource, five type regions where they are suitable for maize planting was divided using GIS technology. Divisional results will have a reasonable arrangement for different varieties in different ecological environment accordingly.The main results are as follow:1 Ecological adaptability of maize hybrid in northeast of ChinaIn northeast China, the hybrid grain yield showed a difference with growth process due to the variable thermal conditions. The grain yield, kernel number, different growing stage days show a strong law of variation from the southernmost city Haichen, Liaoning province in northeast to Arongqi city, the most northern city of the Northeast. The grain yield,1000-kernal weight, entire growth days obeyed a quadratic relationship (P<0.05), with the latitude ascending, the days of emergency were prolonged and the days from silking to physiological maturity or harvest were shortened. Another quadratic relationship (P<0.01) was showed between grain yield and ACT, grain yield and precipitation at post-silking stage, same as 1000-kernal weight. From above results we can conclude that thermal resource at maize entire growth period was the most limit factor influencing maize yield, precipitation was the next factor. Blindly extending the adaptable hybrid without considering its thermal condition would bring about crop failure.2 Thermal resource hybrid needed in northeast of ChinaIn different ecoregion, significant differences in region ACT demand were found among three years (p <0.001). The difference of thermal demand in different sites within one year was not significant (p>0.05). Planting hybrid in these sites required minimum ACT about over 2900℃. Different growing stages. ACT demand showed different. Thermal time difference at emergence stage is quite big. and then is the post-silking stage, the pre-silking stage is little. There is no difference among three years. Zhengdan958 hybrid cultivated in northeast in 2007 to 2009. sites where zhengdan958 hybrid fully matured distributed in the accumulated temperature zone where the ACT over 3000℃. From above study, hybrid features determined its thermal resource in different region was stable, but it has a significant various in different growing stages.3 Thermal resource use efficiency and maize arrangementZhengdan958 hybrid experiment indicated that the whole growing period ACT utilization ratio was about 90.8% for 2007.91.3% for 2008 and 92.1% for 2009, respectively, and the frost-free period utilization ratio was 85.1%,89.1% and 83.1%. respectively. ACT during the entire growing season was used for main division factor and frost-free period for secondary factor to divide the northeast into four adaptable regions. They are containing adaptive areas for medium-late mature varieties.medium mature varieties, medium-early mature varieties and prematurely varieties.Conclusions:It is found in northeast China that geographical characteristics and terrain area determines the frost-free period and ACT through the whole growing time distributed in the map. They are demonstrated as the form of "V" and the thermal resource gradually decreased with the latitude increased. Maize growth and yield and local climatic conditions have significant relationship, and this closely linked to spatial change of ACT and frost-free period. Specific maize varieties need most suitable and suitable accumulated temperature. It is proved that ACT through the whole growing season is the most important factor for adaptive division, and the first frost-free time to emerge early or late will influence the maize materiality degree. So it is essential to determine the adaptable area for maize planting based on above research. Five adaptable areas with detailed area information were divided using GIS technology method. This research results will provide some inference information for guiding or popularizing the maize hybrid in northeast China.