玉米“四两”高产栽培技术研究Ⅱ夏玉米在三熟制中的镶嵌作用

Study on the “Four twos” High yield Corn Cultivated Technology Ⅱ Summer Corn Occupying an Important Place in the Three ripe Cycle

玉米“四两”高产栽培技术研究旨在鄂西北北亚热带与暖温带气候过渡带进行熟制改革，改旱地两熟制（小麦—玉米）为三熟制（小麦—春玉米—夏玉米）。研究结果表明：夏玉米在三熟制中占有承上启下的重要地位。采用掖单１２号，６月底露天营养钵育苗（或７月初直播），密度７万株·ｈｍ－２，定产定肥，在大旱之年平均单产６５０２ｋｇ·ｈｍ－２，利润２２０２元·ｈｍ－２；比ＣＫ（原两熟制麦茬玉米）增产１倍，增利２．２倍。

To study the “four twos” high yield corn cultivated technology is intended to reform the ripe cycle in the northwestern part of Hubei province, which is a transitional area between the north subtropical zone and the warm zone. More specifically, the technology is intended to change the two ripe cycle (wheat→corn) into a three ripe cycle (winter wheat→spring corn→summer corn) in dry land. The experimental results showed that summer corn occupies an important place in the three ripe cycle. The experiment adopts “Yedan No.12” and employs culture technics such as open air growing seedlings in culture pan during the last ten day period of June (or direct seeding period of July during the first ten day), planting density of 70 000 seedling·hm -2 , determining the amount of fertilizers according to the yield. Summer corn obtains an average yield of 6 502 kg·hm -2 , a profit of 2 202 yuan·hm -2 in a dry year. Compared with CK (corn grown after the wheat harvest in the two ripe cycle), the yield increases by 100%, the profit increases by 220%.