Bauerle William L, McCullough Cole, Iversen Megan, Hazlett Michael
Department of Horticulture and Landscape Architecture, Colorado State University, Fort Collins, CO 80523, USA.
Plants (Basel). 2020 Feb 19;9(2):271. doi: 10.3390/plants9020271.
We examined the aging of leaves prior to abscission and the consequences for estimating whole-crown primary production in L. (hemp). Leaves at three vertical positions in hemp crowns were examined from initial full leaf expansion until 42 days later. Photosynthetic capacity decreased as leaves aged regardless of crown position, light intensity, or photoperiod. Although leaves remained green, the photosynthetic capacity declined logarithmically to values of 50% and 25% of the maximum 9 and 25 days later, respectively. Plants grown under +450 μmol m s supplemental photosynthetically active radiation or enriched diffuse light responded similarly; there was no evidence that photoperiod or enriched diffuse light modified the gas exchange pattern. At approximately 14 days after full leaf expansion, leaf light levels >500 μmol m s decreased photosynthesis, which resulted in ≥10% lower maximum electron transport rate at ≥ 20 days of growth period. Furthermore, leaves were saturated at lower light levels as leaf age progressed (≤500 μmol m s). Incorporating leaf age corrections of photosynthetic physiology is needed when estimating hemp primary production.
我们研究了大麻叶片脱落前的衰老情况以及对估算其全冠层初级生产力的影响。从叶片完全展开开始直至42天后，对大麻冠层中三个垂直位置的叶片进行了研究。无论冠层位置、光照强度或光周期如何，随着叶片衰老，其光合能力都会下降。尽管叶片仍保持绿色，但光合能力分别在9天和25天后呈对数下降至最大值的50%和25%。在补充450μmol m⁻² s⁻¹光合有效辐射或增强漫射光条件下生长的植株表现类似；没有证据表明光周期或增强漫射光会改变气体交换模式。在叶片完全展开约14天后，叶片光照水平>500μmol m⁻² s⁻¹会降低光合作用，这导致在生长20天及以上时最大电子传递速率降低≥10%。此外，随着叶片变老（≤500μmol m⁻² s⁻¹），叶片在较低光照水平下就达到饱和。在估算大麻初级生产力时，需要纳入光合生理的叶龄校正。
