间作系统中早期竞争塑造了玉米整株的发育

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在发展中国家间作还广泛存在，在发达国家的可持续农业中间作正在获得越来越多的关注。由于种间植株的相互作用，间作的植物与单作的植物的生长发育有所不同，但是，在混作中植物形态对竞争的适应反应并没有被详细研究。本文描述了玉米（Zea mays）对混作小麦（(Triticum aestivum）的反应。证据显示在间作中玉米对改变的光照环境的早期响应一直影响玉米的整个生育期，产生与单作不同的表现型。本研究对3种不同的耕作系统（玉米单作、玉米小麦小行间（25cm）间作、玉米小麦大行距（44cm）间作）中光合有效辐射（PAR ）、红光：远红光比率（R： FR）、叶片发育、和最终器官的大小进行了比较。与玉米当作相比，间作玉米出叶速率较低、底层叶片和叶鞘长度增加、顶部叶片和叶鞘长度减小、叶片伸长持续时间延长、在发育早期植株底部的R:FR和PAR降低。小麦玉米带小行距间作的效果最强。这些数据表明叶片分化和出叶速率之间在植株水平上的反馈和叶片和叶鞘生长的在植物节位水平的协调。根据协调的规则，提出了一个概念模型用来解释在单作和间作条件下玉米植株的发育规律。

Early competition shapes maize whole-plant development in mixed stands

Mixed cropping is practised widely in developing countries and is gaining increasing interest for sustainable agriculture in developed countries. Plants in intercrops grow differently from plants in single crops, due to interspecific plant interactions, but adaptive plant morphological responses to competition in mixed stands have not been studied in detail. Here the maize (Zea mays) response to mixed cultivation with wheat (Triticum aestivum) is described. Evidence is provided that early responses of maize to the modified light environment in mixed stands propagate throughout maize development, resulting in different phenotypes compared with pure stands. Photosynthetically active radiation (PAR), red:far-red ratio (R:FR), leaf development, and final organ sizes of maize grown in three cultivation systems were compared: pure maize, an intercrop with a small distance (25 cm) between maize and wheat plants, and an intercop with a large distance (44 cm) between the maize and the wheat. Compared with maize in pure stands, maize in the mixed stands had lower leaf and collar appearance rates, increased blade and sheath lengths at low ranks and smaller sizes at high ranks, increased blade elongation duration, and decreased R:FR and PAR at the plant base during early development. Effects were strongest in the treatment with a short distance between wheat and maize strips. The data suggest a feedback between leaf initiation and leaf emergence at the plant level and coordination between blade and sheath growth at the phytomer level. A conceptual model, based on coordination rules, is proposed to explain the development of the maize plant in pure and mixed stands.

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