Studies On Characteristics Of Morphotogy And Physiology Of Summer Maize Hybrid Varieties With High Yield Potential In The Ecological Area Of The Huanghe-huaihe-haihe Plain

From 1997 to 1998, 16 maize hybrids widely planted in Huang-Huai-Hai Plain were selected to investigate both morphological and physiological characters of superhigh yield maize hybrids, the results are as follows:1. Yield components: mid-larger ear varieties with 1000 grain weight 360 grams and number of kernel per area 3643.22 may be chosen as superhigh yield cultivate variety. Superhigh yield maize hybrids have characters of both higher number of kernel per ear and higher kernel weight per unit. But they have different effect on yield, range of the number of grain varies wider than 1000-kernel weights, then the former has larger direct effect on yield than the latter.2. Dry matter production and distribution: for superhigh yield maize hybrids, Biological yield per area is more than 2250 grams, From anthesis to maturity the percentage dry matter accumulation is over 60% of the final biological yield, harvest indexes is more than 50%, the ratio of kernel weight to ear weight is 89%, dry matter production rate was more than 24 grams and about 28 grams per square meter per day throughout the growing period and after anthesis respectively. Partial correlations Analysis shows that biological yield, harvest index and dry matter accumulation (DMA) after anthesis were positively significant correlated with yield at level 95%. superhigh yield maize hybrids have characters of both higher biological yields and higher harvest index ^specially, the higher dry matteraccumulation at postgrowth stage is one of important property of maize with superhigh yield.3. Root system characters: the number of brace root amounts to more than 110 at silking stage. (2) The value of initial embryonic root activity is higher, coming to no less than 280 TTFug.g-l.Fw.h -1, the root activity decreases slowly after anthesis, 30 days after silking the percentage was 90% of silking stage. There are significant correlations between yield and numbers of brace root at silking, and root activity 30 days after silking at level 95%. Brace root, which is the main component of the post growth root system, makes a difference to accumulate dry matter. It is indispensable for superhigh yield that the root absorbing activity was higher in seedling and decrease slowly after silking.4. Leaf area characters: the dynamic of leaf area was fast, steady and subtractive respectively before anthesis, after anthesis and dough stages. The most leaf area index (LAI) was 5.5, and 0.4 in seedling, maintained 2.5 in maturity, the leaf area duration (LAD) after anthesis achieved 69% of total LAD 300 m2.d.m-2.It is suggested, therefore, higher LAD and higher percentage in the postgrowth period was necessary for superhigh yield hybrids5. Growing period characters: in Huang-Huai-Hai Plain growing time of superhigh yied hybrids was 100-105 days, filling stage remains over 50 days.6. Morphological characters: the superhigh yield maize hybrids was compact-type, proper height, stem diameter was 2.5cm, and appropriate disease resistant and lodge resistant.