Weng Xiaohang, Li Hui, Ren Chengshuai, Zhou Yongbin, Zhu Wenxu, Zhang Songzhu, Liu Liying
College of Forestry, Shenyang Agricultural University, Shenyang, China.
Research Station of Liaohe-River Plain Forest Ecosystem, Chinese Forest Ecosystem Research Network (CFERN), Shenyang Agricultural University, Shenyang, China.
Front Plant Sci. 2022 May 10;13:887098. doi: 10.3389/fpls.2022.887098. eCollection 2022.
As a crucial element for plants, calcium (Ca) is involved in photosynthesis and nutrient absorption, and affects the growth of plants. Poplar is an important economic forest and shelter forest species in China. However, the optimum calcium concentration for its growth is still unclear. Herein, we investigated the growth, biomass, photosynthetic pigments, photosynthetic parameters and products, chlorophyll fluorescence parameters, water use efficiency (iWUE), and antioxidant enzyme activity of "Liao Hu NO.1" poplar ( × ) seedlings at 0, 2.5, 5, 10, and 20 mmol·L concentrations of Ca, and further studied the absorption, distribution, and utilization of nutrient elements (C, N, P, K, and Ca) in plants. We found that with increasing calcium gradient, plant height and diameter; root, stem, leaf, and total biomasses; net photosynthetic rate (Pn); stomatal conductance (Gs); intercellular carbon dioxide (Ci) level; transpiration rate (Tr); ratio; ratio; chlorophyll-a; chlorophyll-b; soluble sugar and starch content; superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) levels; and long-term water use efficiency (iWUE) of poplar seedlings first increased and then decreased. These parameters attained maximum values when the calcium concentration was 5 mmol·L, which was significantly different from the other treatments ( < 0.05). Moreover, a suitable Ca level promoted the absorption of C, N, P, K, and Ca by various organs of poplar seedlings. The absorption of C, N, P, and K increased first and then decreased with the increased calcium concentration, but the optimum calcium concentrations for the absorption of different elements by different organs were different, and the calcium concentration in leaves, stems, and roots increased gradually. Furthermore, the increase in exogenous calcium content led to a decreasing trend in the C/N ratio in different organs of poplar seedlings. C/P and N/P ratios showed different results in different parts, and only the N/P ratio in leaves showed a significant positive correlation with Ca concentration. In conclusion, the results of this study indicate that 5 mmol·L concentration of Ca is the optimal level, as it increased growth by enhancing photosynthesis, stress resistance, and nutrient absorption.
钙（Ca）作为植物的关键元素，参与光合作用和养分吸收，并影响植物生长。杨树是中国重要的经济林和防护林树种。然而，其生长的最佳钙浓度仍不清楚。在此，我们研究了“辽葫1号”杨树（×）幼苗在钙浓度为0、2.5、5、10和20 mmol·L时的生长、生物量、光合色素、光合参数及产物、叶绿素荧光参数、水分利用效率（iWUE）和抗氧化酶活性，并进一步研究了植物中营养元素（C、N、P、K和Ca）的吸收、分布和利用情况。我们发现，随着钙梯度的增加，杨树幼苗的株高和地径；根、茎、叶和总生物量；净光合速率（Pn）；气孔导度（Gs）；胞间二氧化碳（Ci）水平；蒸腾速率（Tr）； 比值； 比值；叶绿素a；叶绿素b；可溶性糖和淀粉含量；超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）水平；以及长期水分利用效率（iWUE）均先升高后降低。当钙浓度为5 mmol·L时，这些参数达到最大值，与其他处理差异显著（<0.05）。此外，适宜的钙水平促进了杨树幼苗各器官对C、N、P、K和Ca的吸收。C、N、P和K的吸收随着钙浓度的增加先增加后降低，但不同器官吸收不同元素的最佳钙浓度不同，叶片、茎和根中的钙浓度逐渐增加。此外，外源钙含量的增加导致杨树幼苗不同器官中C/N比呈下降趋势。C/P和N/P比在不同部位表现不同，只有叶片中的N/P比与钙浓度呈显著正相关。总之，本研究结果表明，5 mmol·L的钙浓度是最佳水平，因为它通过增强光合作用、抗逆性和养分吸收促进了生长。
