在粮食需求不断增加，耕地面积有限的矛盾下，耐密植性状成为了作物育种的重要目标。育种家们都在努力改良株型以培育耐密植品种。而最新的研究结果表明，植物在密植状态下会改变自身的生长角度以接收到更多的阳光滋养。
来自于阿根廷和澳大利亚的研究人员发现，向日葵在密植条件下，会自发改变生长角度，以避开相邻植株的干扰。整体上看，整个群体可形成整齐交错、形如波浪的生长状态。深入研究发现，向日葵的这种“自发规划”的生长状态是受到红光和远红光比例调节的。当密植状态下，由于互相的遮蔽，红光和远红光比例下降。光信号的改变被光敏色素受体感知，从而改变茎的生长角度，调整植株的生长方向。经测定，相比于常规的株距，10-14株/m2的密植状态下，向日葵出油量可提升19-47%。
Proc Natl Acad Sci U S A. 2017 Jul 10.
Light-mediated self-organization of sunflower stands increases oil yield in the field
Author
López Pereira M, Sadras VO, Batista W, Casal JJ, Hall AJ*.
*: Facultad de Agronomía, Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura, Universidad de Buenos Aires/Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires C1417DSE, Argentina.
Abstract
Here, we show a unique crop response to intraspecific interference, whereby neighboring sunflower plants in a row avoid each other by growing toward a more favorable light environment and collectively increase production per unit land area. In high-density stands, a given plant inclined toward one side of the interrow space, and the immediate neighbors inclined in the opposite direction. This process started early as an incipient inclination of pioneer plants, and the arrangement propagated gradually as a "wave" of alternate inclination that persisted until maturity. Measurements and experimental manipulation of light spectral composition indicate that these responses are mediated by changes in the red/far-red ratio of the light, which is perceived by phytochrome. Cellular automata simulations reproduced the patterns of stem inclination in field experiments, supporting the proposition of self-organization of stand structure. Under high crop population densities (10 and 14 plants per m2), as yet unachievable in commercial farms with current hybrids due to lodging and diseases, self-organized crops yielded between 19 and 47% more oil than crops forced to remain erect.
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