root growth include these except( A.less irrigate B.control nutrients C.more intertill D.no intertill 27.Maize is domesticated in which part in the world initially? A.Asia B.Europe C.Mesoamerica D.Africa 28.Which country produces almost half of the world's harvest? A.United States B.China C.Brazil D.Mexico Africa 29.Choose the correct description about maize( A.maize is a long day plant B.maize is shade tolerance C.maize is a cross pollination crop D.maize is a self pollination crop 30.Which description about alfalfa is wrong?( A.alfalfa is a long day plant B.alfalfa is a C plant C.alfalfa is a cross pollination crop D.alfalfa can tolerate waterloging 31.If alfalfa is introduced from south to north in China,then the ripening stage might be( A.postponed B.advanced C.unchanged D.unsure 32.Which type of cor is most ofen used for animal feeding? A.flint comn B.dent corn C.sweet corn D.popcorn 33.The fertilizer critical period of com is( A.trefoil stage B.big horn period C.sweet corn D.popcorn 34.For maize culture,phosphate fertilizer should be used as( A.basal fertilizer B.seed fertilizer C.top dressing D.green manure 35.For maize culture,more than half of nitrogen fertilizer should be used at( A.seedling stage B.heading stage C.flower stage D.ripening stage 36.Smooth brome grass is( A.perennial and prostrate B.perennial and erect C.biennial and prostrate D.biennial and erect 37.White clover is( A.perennial and prostrate B.perennial and erect C.biennial and prostrate D.biennial and erect 38.Italian ryegrass is( A.perennial and prostrate B.perennial and erect C.annual and prostrate D.annual and erect 39.Perennial ryegrass is adapt to such environment conditions( A.cold B.drought C.warm and moist D.warm and dry root growth include these except( ) A.less irrigate  B.control nutrients C.more intertill D. no intertill  27. Maize is domesticated in which part in the world initially?  A.Asia  B.Europe  C. Mesoamerica D. Africa  28. Which country produces almost half of the world's harvest?  A.United States B. China  C. Brazil  D. Mexico Africa 29. Choose the correct description about maize( ) A.maize is a long day plant B.maize is shade tolerance C.maize is a cross pollination crop  D. maize is a self pollination crop  30. Which description about alfalfa is wrong?( ) A.alfalfa is a long day plant B.alfalfa is a C3 plant  C. alfalfa is a cross pollination crop  D. alfalfa can tolerate waterloging  31. If alfalfa is introduced from south to north in China,then the ripening stage might  be(  ) A.postponed  B.advanced  C.unchanged  D.unsure  32. Which type of corn is most often used for animal feeding?  A.flint corn B. dent corn C.sweet corn D.popcorn  33. The fertilizer critical period of corn is ( ) A.trefoil stage B. big horn period  C.sweet corn D.popcorn  34. For maize culture,phosphate fertilizer should be used as ( ) A.basal fertilizer B.seed fertilizer C.top dressing  D.green manure  35. For maize culture,more than half of nitrogen fertilizer should be used at ( ) A.seedling stage B.heading stage C. flower stage  D.ripening stage 36. Smooth brome grass is ( ). A.perennial and prostrate  B. perennial and erect  C.biennial and prostrate  D. biennial and erect  37. White clover is ( ) A.perennial and prostrate  B. perennial and erect  C.biennial and prostrate  D. biennial and erect  38. Italian ryegrass is( ) A.perennial and prostrate  B. perennial and erect  C.annual and prostrate  D. annual and erect  39. Perennial ryegrass is adapt to such environment conditions( ) A.cold  B. drought C.warm and moist D.warm and dry