低温导致矮秆的玉米适合在洞穴、矿井内种植
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美国印第安纳州西拉斐特
2014年5月12日
研究人员Yang Yang（左）和Cary Mitchell。（照片由普渡大学提供）
普渡大学的研究显示：每天2个小时的低温可降低玉米高度但不会影响籽粒产量，这项技术可以用来在洞穴和废弃矿井中的控制环境设施种植农作物。
在隔离和封闭的环境种植作物可以避免转基因花粉和种子扩散到生态系统与野生植物杂交。
普渡大学园艺教授Cary Mitchell说：对以从植物衍生的工业用和医药用化合物的工业，该技术有助于植转基因作物并生产高价值的药用产品（如抗体）。
“通过遗传工程设计，玉米籽粒可生产蛋白质，用于提取加工成医药、药品和保健品，比如，人体必需的维生素，”他说。“这是一个年轻的行业，我们完成的这项研究显示可以成功地在控制环境中种植这些高价值的作物。”
Mitchell说：对这一行业来说，玉米是一个“很好的候选作物”，因为玉米植株可以生产大量的种子和其基因组已经被广泛研究，适合于进行多种遗传改造。利用植物作为“工厂”生产具有生物活性的药物将远比现在依赖于哺乳动物的细胞培养的方法便宜得多。
但是，种植玉米这种高个子作物，需要明亮的光线和热量。阴暗、寒冷的地下矿井对Mitchell和他的博士后研究人员，Yang Yang和Gioia Massa。他们在印第安纳州Marengo的一个前石灰石矿内使用绝缘材料安装了一个生长箱，使用黄色和蓝色的高强度气体放电灯照明，用来测试玉米在光照、温度、湿度和二氧化碳都严格控制的生长环境下的反应。令他们吃惊的杂交玉米长得“特别好“，杨说。
“我们给这些植物提供如此豪华的环境，玉米植株在抽雄前就触及到灯了，”他说。
为了降低玉米的高度，研究人员借鉴在温室产业圣诞节矮秆一品红的技术。他们使用一个生长箱模拟Marengo矿的温度条件和二氧化碳水平，在每个光照周期的前2个小时，将温度降到60华氏度，接下来的14个小时，温度又恢复到80华氏度时，然后在黑暗的8个小时降至65华氏度。
两小时低温使植株高度降低了9〜10％，将茎的直径减少了8〜9％，但对粒数和粒重没有显著的影响。
“您可以轻松地在矿山或洞穴中使用这一技术，”Mitchell说。“这是一种负担得起而且不使用化学药品的方法，可以让转基因作物一直长到收获，而不会有任何种类的花粉或种子进入生态系统。”
他说，废弃的矿井可能是种植高价值的转基因植物的最好地点，因为那里的自然低温环境减弱了需要使用通风来降低灯具产生的热量。矿井中高水平的二氧化碳还可以促进植物生长。
“控制环境中的生产力优于田间的，并且每年可以种植多季作物，”Mitchell说。“控制环境农业将是21世纪的一大趋势。”
Yang Yang1; Gioia D. Massa2; Cary A. Mitchell3
1 Dow AgroSciences LLC, 9330 Zionsville Road, Indianapolis, IN 46268, USA
2 ISS Ground Processing and Research, NASA Kennedy Space Center, FL 32899, USA
3 Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907-2010, USA
E-mail: cmitchel@purdue.edu
A semi-dwarf breeding line of maize (Zea mays L., PI 587154) was grown from seed to seed in a growth chamber either at 26.7 °C days/18.3 °C nights (control treatment) or at 15.6 °C for the first 2 h of each photoperiod before being returned to standard control temperature for the rest of the photoperiod (DIP treatment). Half of the plants in each 120-day production experiment were grown in 3-L containers and half in 9-L containers, both groupings at equivalent plant-to-plant spacing. Stalks of DIP-treated plants elongated 9-10% less than controls during seed-production cycles in both pot sizes. DIP reduced vegetative dry biomass of stalks 29% relative to controls when using small pots, and 19% for plants grown in medium pots. Root dry weight was reduced 22-25% by DIP in the two container sizes, but stalk/root ratios were not altered significantly by DIP treatment or pot size. Stalk diameter also was reduced 8-9% by DIP for both pot sizes. Neither seed number nor seed weight were affected significantly by temperature treatment or pot size. DIP slowed and prolonged stalk elongation but not differentiation of nodes for both pot sizes. Timing of tassel development and pollen shed were unaffected by temperature or pot size, but timing of silk development was delayed by DIP, slightly more for plants growing in small than in medium pots. Nevertheless, primary ears developed to complete seed fill, suggested adequate time-window overlap between pollen shed and silk receptivity for effective pollination and fertilization to occur. Controlled-environment production of maize in restricted-height growth facilities or where adequate separation distance is required between the tops of crop stands and overhead high-intensity discharge light sources may be accommodated economically by use of DIP temperature treatments without compromising grain yield. Use of medium-volume containers stabilizes the mature maize stalks bearing grain-filled ears.
