Examinando por Autor "Li, Guolei"

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A wider spectrum of avoidance and tolerance mechanisms explained ozone sensitivity of two white poplar ploidy levels
(Oxford, 2023-01-24) Wang, Miaomiao; Li, Guolei; Feng, Zhaozhong; Liu, Yong; Uscola Fernández, Mercedes
Background and Aims Polyploidization can improve plant mass yield for bioenergy support, yet few studies have investigated ozone (O3) sensitivity linked to internal regulatory mechanisms at different ploidy levels. Methods Diploid and triploid Populus tomentosa plants were exposed to ambient and ambient plus 60 ppb [O3]. We explored their differences in sensitivity (leaf morphological, physiological and biochemical traits, and plant mass) as well as mechanisms of avoidance (stomatal conductance, xanthophyll cycle, thermal dissipation) and tolerance (ROS scavenging system) in response to O3 at two developmental phases. Key Results Triploid plants had the highest plant growth under ambient O3, even under O3 fumigation. However, triploid plants were the most sensitive to O3 and under elevated O3 showed the largest decreases in photosynthetic capacity and performance, as well as increased shoot:root ratio, and the highest lipid peroxidation. Thus, plant mass production could be impacted in triploid plants under long-term O3 contamination. Both diploid and triploid plants reduced stomatal aperture in response to O3, thereby reducing O3 entrance, yet only in diploid plants was reduced stomatal aperture associated with minimal (non-significant) damage to photosynthetic pigments and lower lipid peroxidation. Conclusions Tolerance mechanisms of plants of both ploidy levels mainly focused on the enzymatic reduction of hydrogen peroxide through catalase and peroxidase, yet these homeostatic regulatory mechanisms were higher in diploid plants. Our study recommends triploid white poplar as a bioenergy species only under short-term O3 contamination. Under continuously elevated O3 over the long term, diploid white poplar may perform better.
Seedling size and nutrient availability in the fall determine nitrogen resorption and storage compound allocation in Quercus variabilis
(Springer Link, 2022-04-02) Wang, Jiaxi; Uscola Fernández, Mercedes; Li, Guolei
Soil fertility and resorption of leaf compounds in the fall can influence resource buildup in plants. However, whether intraspecific differences in seedling size can affect nutrient reserve buildup is unknown. This study examined the effects of seedling size and fall fertilization on the uptake and resorption of nitrogen (N), as well as the allocation of non-structural carbohydrates (NSC) and N in cultivated Quercus variabilis Blume. After the formation of terminal buds (T1), seedlings were stratified into small (shoot height < 30 cm) and large seedlings. During the hardening period, seedlings were treated with three different rates of 15 N-enriched fertilizer (0, 12, or 24 mg N seedling−1) and monitored until leaf fall (T2). Small seedlings had lower N resorption efficiency and resorbed proportionally less N than large seedlings. Fall fertilization notably improved N and NSC reserves, without reducing N resorption efficiency. Large seedlings allocated proportionally less N to leaves than small seedlings although both sizes seedlings absorbed similar amounts of N from fall fertilization. The priority perennial organ for NSC allocation was roots, while N allocation was dependent on the phenological growth stage of the seedling. Roots were prioritized during the rapid growth phase, while stems were prioritized during the hardening period. Under same fertilizer regime during the growth phase, large seedlings tends to have lower N concentration and have higher resorption efficiency compare to small seedlings, fall fertilization can increase N storage in large seedlings and NSC levels in both seedling sizes, without affecting growth.
The tradeoff strategy between growth and survival in Quercus variabilis seedlings: determining the most limiting resource in the field drive shoot dieback
(Oxford, 2022-12-31) Wang, Miaomiao; Cheng, Zhongqian; Li, Guolei; Wang, Jiaxi; Uscola Fernández, Mercedes
Shoot dieback is an important survival strategy in juvenile Quercus spp. However, it is unknown how nursery practices can influence the regulatory mechanisms of shoot dieback after planting. Furthermore, there is scarce information about the interactive effects between container depth and nursery fertilization on field seedling performance, and in combination with field weed control. Here, Quercus variabilis seedlings were cultivated the first year in with two container depths (25 cm, D40; 36 cm, D60) and with two nitrogen-loading levels (25, N25; 100 mg seedling−1, N100) in the nursery, and the following year, they were out-planted with/without weed elimination. We evaluated first year seedlings’ functional traits after nursery culture (plant and root morphology and nutritional status) and second year field performance (survival, shoot dieback, growth and nutrient increments), and their relationship. Independently of nursery culture, weed management was an irreplaceable practice to optimize seedling field performance. Seedlings grown in deep containers (D60) showed enhanced field growth and nutrient acquisition and reduced shoot dieback. Fertilization increased N and K loading (content and concentration) in the nursery, but showed no effect in the field. Low quality seedlings (low fertilization and normal container) maintained high survival rates at the expense of increasing shoot dieback rate. Thus, field survival did not differ among seedlings with differing nursery practices. Together, deep container and high N fertilization, increased plant nutritional reserves (content) and improved root system development, consequently, mitigating field shoot dieback. Under our experimental conditions, improved seedling quality by the use of deep container (D60) was sufficient to optimize field seedling performance without weed competition. However, both, deep container and nitrogen loading (D60-N100) were the best nursery practices to optimize seedling success without weed control in the field. Our study highlights that shoot dieback is a paramount trade-off strategy between growth and survival, which should be considered as an important indicator for further evaluating seedling field performance.
Uptake of nitrogen forms by diploid and triploid white poplar depends on seasonal carbon use strategy and elevated summer ozone
(Oxford, 2021-10-26) Wang, Miaomiao; Li, Guolei; Feng, Zhaozhong; Liu, Yong; Xu, Yansen; Uscola Fernández, Mercedes
The ability of plants to acquire soil nitrogen (N) sources is plastic in response to abiotic and biotic factors. However, information about how plant preferences among N forms changes in response to internal plant N demand through growth phases, or to environmental stress such as ozone (O3), is scarce. Diploid and triploid Chinese white poplar were used to investigate N form preferences at two key developmental periods (spring, summer) and in response to summer O3 (ambient, 60 ppb above ambient). We used stable isotopes to quantify NH4+, NO3− and glycine N-uptake rates. Carbon acquisition was recorded simultaneously. Both ploidy levels differed in growth, N form preferences, and N and C use strategies. Diploid white poplars grew faster in spring but slower in summer compared with triploids. Diploid white poplars also showed plasticity among N form preferences through the season, with no preferences in spring, and NO3− preferred in summer, while triploids showed an overall preference for NO3−. Carbon acquisition and NO3− uptake were inhibited in both ploidy levels of poplar at elevated O3, which also reduced diploid total N uptake. However, triploid white poplars alleviated N uptake reduction, switching to similar preferences among N forms. We conclude that N form preferences by white poplar are driven by internal C and N use in response to nutrient demands, and external factors such as O3.