Plant Spacing and Reflected Far‐Red Light Effects on Phytochrome‐Regulated Photosynthate Allocation in Corn Seedlings

Abstract

Allocation of photosynthate among leaves, stems, and roots is critical in seedling establishment. Corn (Zea mays L.) seedlings were grown in different spacing patterns in a field and with different reflected far‐red (FR) to red (R) light ratios to test the effects of a modified FR/R ratio on photoassimilate allocation. Green leaves absorbed most of the R and reflected much of the FR. Therefore, close‐spaced plants received more reflected FR and higher FR/R ratios. Seedlings that received the higher FRJR ratios developed longer and narrower leaves, longer stems, and less massive roots. Stem elongation was an early response to increased FR/R ratio even though fight did not impinge directly on the stems, which were initially at or below the soil surface and covered by several layers of leaves. Row orientation did not significantly alter FR/R ratio or seedling morphology because corn leaves are not heliotropic and did not function as directional FR reflectors, as was observed for soybean [Glycine max (L.) Merr.] in a previous study. An increase in the FR/R ratio reflected up to seedlings from the soil surface also resulted in increased shoot size and shoot/root biomass ratio. Early morphological responses of corn seedlings to FR/R ratio in reflected light are relevant to seedling establishment and are not dependent on the cause of the altered ratio.

Morphological and physiological responses of Cedrela Fissilis Vellozo (Meliaceae) seedlings to light

“…3A), indicate that they allocated relatively more of biomass to aerial part than to roots. Generally, plants under the shade invest more in leaves, to optimize light interception (Kasperbauer and Karlen, 1994). The paradigm of optimization has faced severe criticism, due to its tendency to isolate one individual character of an organism integrated to light environment (Valladares and Pearcy, 2000).…”

Mapping reciprocal effects and interactions with plant density stress in Zea mays L.

“…From seedling onwards, maize plants are able to detect neighbors through red/far-red signals (Kasperbauer and Karlen, 1994;Maddonni et al, 2002). Higher plant population densities triggers neighbordetecting mechanisms and responses at earlier developmental stages than lower population densities (Maddonni and Otegui, 2004).…”

Understanding Plant Density Effects on Maize Growth and Development: An Important Issue to Maximize Grain Yield

“…When plant density is increased, plants are closer to each other which enhances the amount of FR reflected by competing seedlings, leading ultimately to a higher FR/R ratio (KASPERBAUER & KARLEN, 1994). An increased FR/R ratio derived from close-spaced plants suppress the development of tillers in wheat (ALMEIDA, 1998), stimulating apical dominance.…”