Examinando por Autor "Wang, Jiaxi"

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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.