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1. chinaXiv:201906.00044 [pdf]

Leaf gas exchange and photosynthesis curves of Elymus nutans and Potentilla anserina under fencing and grazing conditions in the Qilian Mountains, Northwest China

LIU Junjie; WANG Xiaoping
Subjects: Biology >> Botany

Potentilla anserina L. and Elymus nutans Griseb. are dominant species in the subalpine meadows of China. Grazing is one of the most important factors that influence community structure and productivity of subalpine meadows. Understanding how grazing changes photosynthetic capability is essential for preservation and restoration of grasslands. However, information about the effects of grazing on photosynthetic capability remains inadequate. Experiments were conducted in fencing and grazing areas in the Qilian Mountains, Northwest China. The leaf gas exchange and photosynthetic curves of P. anserina and E. nutans were measured at different growth stages. Results showed that grazing decreased the values of leaf gas exchange parameters, such as net photosynthetic rate, stomatal conductance, transpiration rate, and intercellular CO2 concentration of P. anserina and E. nutans. In addition, grazing decreased the values of net photosynthetic rate-photosynthetically active radiation (PN-PAR) curve parameters, such as light-saturated net photosynthetic rate, apparent quantum efficiency, light compensation point, light saturation point, and dark respiration rate. Our results demonstrated that grazing was the primary limiting factor for photosynthesis of dominant grassland species in the study area.

submitted time 2019-06-20 From cooperative journals:《Journal of Arid Land》 Hits2485Downloads154 Comment 0

2. chinaXiv:201906.00043 [pdf]

Low soil temperature reducing the yield of drip irrigated rice in arid area by influencing anther development and pollination

ZHANG Jun
Subjects: Biology >> Botany

Drip irrigation can produce high rice yields with significant water savings; therefore, it is widely used in arid area water-scarce northern China. However, high-frequency irrigation of drip irrigation with low temperature well water leads to low root zone temperature and significantly reduce the rice yield compared to normal temperature water irrigated rice, for example, reservoir water. The main purpose of this paper is to investigate the effects of low soil temperature on the yield reduction of drip irrigated rice in the spike differentiation stage. The experiment set the soil temperatures at 18°C, 24°C and 30°C under two irrigation methods (flood and drip irrigation), respectively. The results showed that, at the 30°C soil temperature, drip irrigation increased total root length by 53% but reduced root water conductivity by 9% compared with flood irrigation. Drip irrigation also increased leaf abscisic acid and proline concentrations by 13% and 5%, respectively. These results indicated that drip irrigated rice was under mild water stress. In the 18°C soil temperature, drip irrigation reduced hydraulic conductivity by 58%, leaf water potential by 40% and leaf net photosynthesis by 25% compared with flood irrigation. The starch concentration in male gametes was also 30% less in the drip irrigation treatment than in the flood irrigation treatment at soil temperature 18°C. Therefore, the main reason for the yield reduction of drip irrigated rice was that the low temperature aggravates the physiological drought of rice and leads to the decrease of starch content in male gametes and low pollination fertilization rate. Low temperature aggravates physiological water deficit in drip irrigated rice and leads to lower starch content in male gametes and low pollination fertilization rate, which is the main reason for the reduced yield of drip irrigated rice. Overall, the results indicated that the low soil temperatures aggravated the water stress that rice was under in the drip irrigated environment, causing declines both in the starch content of male gametes and in pollination rate. Low temperature will ultimately affect the rice yield under drip irrigation.

submitted time 2019-06-20 From cooperative journals:《Journal of Arid Land》 Hits2155Downloads134 Comment 0

3. chinaXiv:201903.00235 [pdf]

Impact of air drought on photosynthesis efficiency of the Siberian crabapple (Malus baccata L. Borkh.) in the forest-steppe zone of Transbaikalia, Russia

Alexandr RUDIKOVSKII
Subjects: Biology >> Botany

The adaption of photosynthesis, being a key metabolic process, plays an important role in plant resistance to air drought. In this study, the Siberian crabapple (Malus baccata L. Borkh.) in the forest-steppe zone of Transbaikalia region, Russia, was subjected to air drought stress and its photosynthesis characteristics were analyzed. The results show that air drought and sufficient soil moisture supply lead to the decrease in the total chlorophyll (Chl) content, while the ratio of Chls to carotenoids is constant in the Siberian crabapple tree. The function of photosystem II (PS-II) in the crabapple trees is characterized by a decrease in the fraction of absorbed light energy spent on the photochemical work and an increase in the proportion of non-photosynthetic thermal quenching. These changes indicate the photosynthetic down-regulation that acts as a universal photoprotective mechanism. During the midday hours, the combination of high air temperature and low air humidity leads to the decrease in the maximum photochemical quantum yield of photosystem II (Fv/Fm) and the efficiency of photosynthesis (PABS). The parameters of leaf gas exchange show the significant differences in these values between the control and experimental variants. During the morning hours, the Siberian crabapple, growing in the Irkutsk City, assimilates carbon dioxide more intensively. Due to the higher air humidity, the stomata are kept open and the necessary amount of carbon dioxide entries the sites of carboxylation. The low air humidity combined with wind in the experimental variants leads to the unreasonably high water loss in the crabapple leaves by more than 27% as compared to the control variant (Irkutsk City). However, water use efficiency in the morning hours increases during plant photosynthetic processes, i.e., 42% higher than that of control. This, apparently, is a reflection of the adaptation processes of the Siberian crabapple to the air drought and parching wind.

submitted time 2019-03-28 From cooperative journals:《Journal of Arid Land》 Hits3034Downloads274 Comment 0

4. chinaXiv:201901.00109 [pdf]

Soil fixation and erosion control by Haloxylon persicum roots in arid lands, Iran

Ehsan ABDI; Hamid R SALEH
Subjects: Biology >> Botany

Vegetation roots contribute to soil fixation and reinforcement, thus improving soil resistance against erosion. Generally, the amount of soil fixation presented by roots mainly depends on root density and tensile strength. In the present study, we conducted the research in order to further understand the biotechnical properties of Haloxylon persicum and also to quantify its role in increasing soil cohesion in arid lands of Iran. Ten H. persicum shrubs were randomly selected for root distribution and strength investigations, in which five samples were set on flat terrain and other five samples on a moderate slope terrain. The profile trench method was used to assess the root area ratio (RAR) as the index of root density and distribution. Two profiles were dug around each sample, up and downslope for sloped treatment and north and south sides for flat treatment. The results showed that RAR increased with increasing soil depth and significantly decreased in 40–50 cm layers of downhill (0.320%) and 50–60 cm for uphill (0.210%). The minimum values for the northward and southward profiles were 0.003% and 0.003%, respectively, while the maximum values were 0.260% and 0.040%, respectively. The relationship between the diameter of root samples and root tensile strength followed a negative power function, but tensile force increased with increasing root diameter following a positive power function. The pattern of increased cohesion changes in soil profile was relatively similar to RAR curves. The maximum increased cohesion due to the presence of roots in uphill and downhill sides were 0.470 and 1.400 kPa, respectively. In the flat treatment, the maximum increased cohesions were 0.570 and 0.610 kPa in northward and southward profiles, respectively. The analysis of variance showed that wind and slope induced stresses did not have any significant effect on the amount of increased cohesion of H. persicum. The findings served to develop knowledge about biotechnical properties of H. persicum root system that can assist in assessing the efficiency of afforestation and restoration measures for erosion control in arid lands.

submitted time 2019-01-17 From cooperative journals:《Journal of Arid Land》 Hits2035Downloads198 Comment 0

5. chinaXiv:201812.00154 [pdf]

樟叶越桔组培苗生根和移栽技术研究

赵展平(1,2); 何芳(1); 唐军荣(2); 罗旭璐(2); 赵平(2); 黄荐(2); 丁勇(1)
Subjects: Biology >> Botany

樟叶越桔(Vaccinium dunalianum Wight)是广泛应用于化妆品行业皮肤美白的天然美白活性剂原料熊果普的主要植物来源之一,采用植物组织培养技术进行种苗繁殖时,现有的配方获得的生根苗基部会形成愈伤组织,影响移栽。为解决樟叶越桔组培苗生根质量不佳、移栽成活率低的问题,本研究以樟叶越桔继代苗为试验材料,采用单因子实验从激素类型及浓度、培养基类型和蔗糖质量浓度对其生根的适宜条件进行了筛选,并进一步研究了不同基质配比对樟叶越桔移栽苗存活率的影响。结果表明:激素种类和浓度、培养基类型对樟叶越桔生根率影响最大,其次为蔗糖质量浓度;最适合樟叶越桔生根的激素及浓度为IBA 2.0mg.L_1、基本培养基类型为1/4MS、蔗糖质量浓度为15 g}L-',樟叶越桔组培苗最佳生根培养基为1/4MS + IBA 2.0 mg}L-1+活性炭0.1 g}L-'+蔗糖15 g}L-',生根率达100%,平均生根数为7.67条/株;根系呈辐射状、基部无愈伤组织,组培苗生长健壮、叶色浓绿;樟叶越桔组培苗移栽时以全腐殖土基质为佳,成活率达83.7%,植株叶片舒展,生长状况良好。本研究建立的优化体系有效地提高了樟叶越桔组培生根苗的生根率和生根质量,解决了后期移栽成活困难的问题,为优良的樟叶越桔植株规模化生产提供了科学依据和技术支持。

submitted time 2018-12-19 From cooperative journals:《广西植物》 Hits704Downloads227 Comment 0

6. chinaXiv:201811.00102 [pdf]

Phenotypic plasticity of Artemisia ordosica seedlings in response to different levels of calcium carbonate in soil

XUE Pingping; ZHAO Xuelai; GAO Yubao; HE Xingdong
Subjects: Biology >> Botany

Plant phenotypic plasticity is a common feature that is crucial for explaining interspecific competition, dynamics and biological evolution of plant communities. In this study, we tested the effects of soil CaCO3 (calcium carbonate) on the phenotypic plasticity of a psammophyte, Artemisia ordosica, an important plant species on sandy lands in arid and semi-arid areas of China, by performing pot experiments under different CaCO3 contents with a two-factor randomized block design and two orthogonal designs. We analyzed the growth responses (including plant height, root length, shoot-leaf biomass and root biomass) of A. ordosica seedlings to different soil CaCO3 contents. The results revealed that, with a greater soil CaCO3 content, A. ordosica seedlings gradually grew more slowly, with their relative growth rates of plant height, root length, shoot-leaf biomass and root biomass all decreasing significantly. Root N/P ratios showed significant negative correlations with the relative growth rates of plant height, shoot-leaf biomass and root length of A. ordosica seedlings; however, the relative growth rate of root length increased significantly with the root P concentration increased, showing a positive correlation. These results demonstrate that soil CaCO3 reduces the local P availability in soil, which produces a non-adaptive phenotypic plasticity to A. ordosica seedlings. This study should prove useful for planning and promoting the restoration of damaged/degraded vegetation in arid and semi-arid areas of China.

submitted time 2018-11-23 From cooperative journals:《Journal of Arid Land》 Hits927Downloads333 Comment 0

7. chinaXiv:201807.00072 [pdf]

云南德宏傣族传统村落植物景观及应用研究

周静帆; 欧杨; 周丽; 刘昕岑; 包蓉
Subjects: Biology >> Botany

传统村落的植物景观,反应了一个民族在长期实践中积累的植物认知和应用经验,兼具地域自然性与文化性,从而对村落生态环境建设及民族植物的可持续性利用具有重要参考意义。该研究对云南省德宏州大盈江、瑞丽江流域的19个傣族传统村落进行植物景观及应用调查。结果表明:德宏傣族传统村落植物景观水平分布为寨外(山林绿块+农田绿块+护堤绿带)——寨边(防护绿环+高山榕绿块)——寨内(绿点+绿线)的格局;垂直分布有5个景观层次;村寨内常见植物共181种,73科;村寨内植物多为人工栽培,具较强实用性,主要应用功能集中在食用、药用、观赏、防护隔离、香薰调味等方面;傣寨植物人文景观具宗教色彩。建议加强植物水平分布的空间联系,建立稳定的绿地系统格局;保持植物垂直景观层次,推广植物的建造功能应用;充分利用植物资源,形成产业优势;传承优秀的植物文化景观。最终,推广植物在村落建设中的传统应用经验,促进民族村落与植物的可持续保护与发展。该研究成果对德宏傣族人居环境建设与民族植物学应用提供了科学依据。

submitted time 2018-07-13 From cooperative journals:《广西植物》 Hits2343Downloads957 Comment 0

8. chinaXiv:201807.00033 [pdf]

Grazing every month minimizes size but boosts photosynthesis in Stipa grandis in the steppe of Inner Mongolia, China

LI Xiaobing; HUANG Qi; MI Xue; BAI Yunxiao; ZHANG Meng; LI Xu
Subjects: Biology >> Botany

In order to explore the effects of grazing frequency on functional traits and to test whether Stipa gandis has compensatory photosynthesis during the frequent grazing period, we investigated morphological traits, biomass allocation, photosynthetic traits, and chlorophyll fluorescence parameters of the species in Inner Mongolia, China. The grazing frequency treatments included fencing (T0), grazing in May and July (T1, i.e., two months per year) and grazing from May to September (T2, i.e., continuous five months per year). Results indicate that T1 and T2 treatments did not affect individual biomass, but T2 treatment negatively affected individual size, i.e., plant height, stem length, and leaf length. Physiological traits of S. grandis were significantly affected by grazing, year, and their interaction. In July 2014 (i.e., dry environment and low relative humidity), the photosynthetic rate, transpiration rate and water use efficiency were highest under T2 treatment, which was caused by the increase in stomatal conductance. However, in July 2015 (i.e., wet environment and high relative humidity), the photosynthetic rate and water use efficiency were higher under T1 and T2 treatments, which were caused by the increase in actual quantum efficiency and stomatal conductance. Our results implied that under frequent grazing treatment, S. grandis had small height and efficient compensatory photosynthesis, which promoted its resistance to severe grazing.

submitted time 2018-07-05 From cooperative journals:《Journal of Arid Land》 Hits1409Downloads358 Comment 0

9. chinaXiv:201807.00034 [pdf]

Precipitation amount and frequency affect seedling emergence and growth of Reaumuria soongarica in northwestern China

SHAN, Lishan; ZHAO, Wenzhi; LI, Yi; ZHANG, Zhengzhong; XIE, Tingting
Subjects: Biology >> Botany

Climate change is shifting the amount and frequency of precipitation in many regions, which is expected to affect seedling recruitment across ecosystems. However, the combined effects of precipitation amount and frequency on seedling recruitment remain largely unknown. An understanding of the effects of precipitation amount and frequency and their interaction on seedling emergence and growth of typical desert plants is vital for managing populations of desert plants. We conducted two experiments to study the effects of variation in precipitation on Reaumuria soongarica (Pall.) Maxim. First, greenhouse experiments were conducted to examine the effects of three precipitation amount treatments (ambient, +30%, and −30%) and two precipitation frequency treatments (ambient and −50%) on seedling emergence. Second, the morphological responses of R. soongarica to changes in precipitation amount and frequency were tested in a controlled field experiment. Stage-specific changes in growth were monitored by sampling in different growth seasons. Our results showed that precipitation amount significantly affected germination, seedling emergence, and growth of R. soongarica, and there was a larger effect with decreased precipitation frequency compared with ambient. Germination and seedling emergence increased as precipitation increased under the same frequency of precipitation. The highest emergence percentage was obtained with a 30% increase in precipitation amount and a 50% reduction in precipitation frequency. Compared with ambient precipitation, a 30% increase in precipitation amount increased above- and below-ground biomass accumulation of R. soongarica during the growth season. A decrease of 30% in precipitation amount also resulted in an increase in below-ground biomass and root/shoot ratio in the early stages of the growth season, however, above- and below-ground biomass showed the opposite results at the end of the growth season, with larger effects on above-ground than below-ground biomass under decreased precipitation frequency. When precipitation frequency decreased by 50%, values of all growth traits increased for a given amount of precipitation. We concluded that precipitation frequency may be as important as precipitation amount to seedling emergence and growth of R. soongarica, and that understanding the effects of precipitation variability on seedling recruitment requires the integration of both precipitation amount and frequency. In particular, the combination of a 30% increase in precipitation amount and 50% reduction in precipitation frequency increased the emergence and growth of seedlings, suggesting that alteration of amount and frequency of precipitation caused by climate change may have significant effects on seedling recruitment of R. soongarica.

submitted time 2018-07-05 From cooperative journals:《Journal of Arid Land》 Hits1554Downloads379 Comment 0

10. chinaXiv:201806.00134 [pdf]

鄱阳湖苦草及马来眼子菜PSⅡ荧光参数对水深变化的光响应

高桂青; 吕顺华; 吕念泽; 卢龙; 李威; 计勇; 游济康; 万鹏
Subjects: Biology >> Botany

:以鄱阳湖湿地典型沉水植物苦草和马来眼子菜为供试材料, 通过吊桶实验控制水位,利用水下饱和脉冲调制叶绿素荧光仪(Diving-pam)研究不同水深(0.5、1.0、1.5、2.0、2.5 m)对两种植物叶片最小荧光Fo、最大荧光Fm、 PSⅡ最大光化光效率Fv/Fm、有效量子产量Y(Ⅱ)、光化学淬灭系数qP、非光化学淬灭系数qN、非调节性能量耗散的量子产量Y(NO)等荧光参数的影响,探讨各个参数随水深的变化规律。研究结果表明:水深1.5-2.0 m处苦草生物量最大,1.0-1.5 m处马来眼子菜生物量最大;两种植物的Fo均先降低后升高,而荧光参数(FmFv/FmFv/FoY(Ⅱ)qP)均呈现先升高后降低趋势;2.0 m处苦草的Fv/Fm、Fv/Fo达到最大,1.5 m处马来眼子菜达到最大;相同水深下,马来眼子菜的qN比苦草低,与qP变化趋势相反;苦草的Y(Ⅱ)最大值出现在水深1.5-2.0 m范围内,马来眼子菜的Y(Ⅱ)最大值出现在1.5 m处;两者Y(NO)随水深变化均表现出显著差异,过高或过低水深均抑制植物生长;相对光合电子传递速率ETR在不同的水深处理间均差异显著,苦草的最大ETR比马来眼子菜小,说明其有较强的耐弱光能力。综上所述,可通过测定植物叶片荧光特性来反映水深变化,为湖泊水位调控提供参考。在试验条件下,水深1.5-2.0 m苦草光合能力最强,最适宜生长;水深1.0-1.5 m最适宜马来眼子生长。

 

 

submitted time 2018-06-19 From cooperative journals:《广西植物》 Hits1274Downloads411 Comment 0

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