Perspectives on Drought Preconditioning Treatments With a Case Study Using Western Larch

As the demand for drought hardy tree seedlings rises alongside global temperatures, there is a need to optimize nursery drought preconditioning methods to improve field performance of planted seedlings. This perspective article advocates for a more holistic approach to drought preconditioning research that considers the moderating role of plant developmental stage on the effects of drought preconditioning. We identify discrepancies in past studies of root growth potential (RGP) responses to drought preconditioning and highlight studies that suggest such discrepancies may result from inconsistencies among studies in the timing of drought preconditioning implementation. We then illustrate our perspective by presenting original research from an aeroponic RGP trial of 1st-year western larch (Larix occidentalis Nutt.) seedlings exposed to three soil moisture contents for 6months. We evaluated whether drought preconditioning could be used to increase the ratio of root: foliar tissue mass or enhance seedling physiological vigor during a subsequent growth period. Drought preconditioning was found to increase the ratio of root: foliar tissue mass and enhance seedling physiological vigor. Specifically, soil moisture content related negatively with new root biomass, positively with new foliar biomass, and negatively with the length and number of new roots (p<0.001). Meanwhile, the mass of lateral root production following drought preconditioning, but prior to aeroponic growth, correlated weakly to the mass, count, and length of new roots produced during aeroponic growth. We propose that evaluating the importance of the timing of drought preconditioning treatments constitutes an important research frontier in plant science.

Root Growth Potential and Microsite Effects on Conifer Seedling Establishment in Northern Idaho

Environmental conditions and seedling quality interact to produce complex patterns of seedling survival and growth. Root growth potential (RGP) is one metric of seedling quality that can be rapidly measured prior to planting, but the correlation of RGP and seedling performance is not consistent across studies. Site factors including microsite objects that cast shade and competing vegetation can also influence seedling performance. We examined the effects of RGP, presence/absence of a microsite object, and competition cover on the survival and growth of three native conifers to the Inland Northwest, USA, over 5 years. We found that RGP had no effect on the survival or growth of western larch (Larix occidentalis), Douglas fir (Pseudotsuga menziesii var. glauca), and grand fir (Abies grandis) at a mesic north aspect site and a xeric south aspect site. Comparatively, the presence of a microsite increased the odds of survival by 37% for western larch and 158% for grand fir, while the absence of forb cover increased the odds of survival of western larch by 72% and of grand fir by 26%. Douglas fir was less sensitive to microsites and competition. The strong effects of neighborhood conditions around seedlings help inform silvicultural practices to enhance the establishment of western larch and grand fir, including planting seedlings near shading objects and competition control, while these practices may not be as important for Douglas fir.

A method for continuously monitoring the quality of Masson pine seedlings

Root growth potential (RGP) is a popular physiological indicator used to evaluate seedling vigor. However, the time scale used in the RGP test is the order of days, which leads to poor performance of the RGP method. We propose an optical interference method, called statistical interferometry, to measure minute root elongation at a sub-nanometer scale, which can decrease the time used in measuring RGP. The time scale of this method is also 104 times less than that of the RGP method. Because we can measure the length of root elongation continuously, we can compute the root elongation rate (RER), which is the variety of the length of root elongation per second. Continuous monitoring can help determine the quality of Masson pine seedling as soon as possible. To show the effectiveness of our proposed method, we designed an experiment, in which we applied different water stresses to our collected Masson pine seedlings and acquired two groups of pines, representing two different qualities: one stressed by water and one not. After measuring the RER of the groups in our experiments, we found that RER is interrelated with the quality of seedlings.

Children With Congenital Disease Amenable To Aortic Valve Repairs: Lessons For Management And Where Do These Techniques Currently Stand?

Aortic Valve Repair (AVRep) appeared to be the first considered in the armamentarium to treat AV disease in children of various ages for the last two decades because of its lifelong durability and reproducibility. Several advantages of AV Rep over techniques of Aortic Valve Replacement (AVR) are identified. Surgical repair strategy should be individualized to the age of the patient depending on aortic root growth potential. New repair techniques developed by innovative surgeons are gradually becoming adopted.

Prevalence and progression of aortic dilatation in adult patients with Turner syndrome: a cohort study

Objective: Turner syndrome (TS) is a rare disorder affecting 1/2500 female newborn. Aortic dilatation (AD) and aortic dissection represent a major concern in TS. The aims of our study were to describe the aortic root growth, potential aortic dilatation (AD) risk factors and cardiovascular outcomes in a cohort of patients with TS. Methods: Among 204 adult patients included, 197 were studied using a standardized 1.5 Tesla MRI protocol. AD was defined as an aortic diameter ≥20 mm/m2 at the Valsalva sinuses and/or at the ascending aorta, when indexed to body surface area. Results: At baseline, AD was present in 81/197 (41.1%) and 32/197 (16.2%) of patients, at the levels of Valsalva and ascending aorta, respectively. The aortic Valsalva diameter was larger in patients treated for thyroiditis (P < 0.001). Potential risk factors of AD were aging (P < 0.001) and the presence of bicuspid aortic valve (BAV) (P = 0.002). The hazard ratio (HR) of AD occurrence in the presence of BAV was 2.2 (95% CI: 1.33–3.71). After a median follow-up period of 5.1 years (n = 143), AD was present in 58/143 (40.6%) and 25/143 (17.5%) of patients at the levels of Valsalva and ascending aorta, respectively. The median aortic growth of the Valsalva sinuses remained stable. At the ascending aorta, it increased by 0.14 ± 0.61 mm/year. Only one aortic-related death was observed. Conclusion: AD is common in adult patients with TS. However, our results are rather reassuring, as the median aortic diameters remained stable after 5.1 years and few aortic events were observed.

A method for continuously monitoring the quality of Masson pine seedlings

Root growth potential (RGP) is a popular physiological indicator used to evaluate seedling vigor. However, the time scale used in the RGP test is the order of days, which leads to poor performance of the RGP method. We propose an optical interference method, called statistical interferometry, to measure minute root elongation at a sub-nanometer scale, which can decrease the time used in measuring RGP. The time scale of this method is also 104 times less than that of the RGP method. Because we can measure the length of root elongation continuously, we can compute the root elongation rate (RER), which is the variety of the length of root elongation per second. Continuous monitoring can help determine the quality of Masson pine seedling as soon as possible. To show the effectiveness of our proposed method, we designed an experiment, in which we applied different water stresses to our collected Masson pine seedlings and acquired two groups of pines, representing two different qualities: one stressed by water and one not. After measuring the RER of the groups in our experiments, we found that RER is interrelated with the quality of seedlings.Author summaryLi Wang have worked in Nanjing Forest University. His interesting includes machine learning, computer vision and plant phenotype.

Does woody species with contrasting root architecture require different container size in nursery?

Small containers used in seedlings production of tree species with different root architecture can result in serious constraints for root growth and unsuitable plant quality, with potential impacts on field performance. We compare responses of root morphology to changes in container size and shape in both deep-rooting (Acacia caven) and shallow-rooting (Baccharis linearis) species, both commonly used in active restoration plans in central Chile. For both species, seedlings were cultivated in four different PVC container-types varying in size (440 mL and 880 mL) and shape ([10, 20, 35, and 45] cm in length), and a control treatment that consists in the commonly container-type used in Chilean nurseries (440 mL black polyethylene bag). Seedlings were cultivated for one growing season under controlled conditions and a set of above- and belowground morphological parameters were evaluated. A second short experiment was performed afterwards to evaluate potential seedling quality through the root growth potential (RGP) test. Results showed that an increase in container volume differently affected morphological parameters of A. caven and B. linearis seedlings. The control treatment had high presence of spiral roots for the deep-rooting species, restricting normal root growth. For both species, elongated containers (>35 cm) produced seedlings with smaller shoots with longer root systems and without deformations in the taproot or main root. Elongated containers also restarted growth of new roots more deeply in the container as result of the RGP test. We concluded that contrasting root architecture of native species require different container size in nursery to promote an adequate root development and growth.

Restoration of European yew (Taxus baccata L.) in Mediterranean mountains: importance of seedling nursery fertilization and post-planting light levels

<p><em>Aim of the study:</em> We studied the influence of nursery fertilization and post-planting light environment on the growth and survival of out-planted two-year-old yew (<em>Taxus baccata</em>) seedlings.</p><p><em>Area of study:</em> Post-planting performance was assessed at two sites in the Valsain Forest (Central Mountain Range, Segovia, Spain).</p><p><em>Materials and Methods:</em> Seedlings were grown using the same seed-lot, container type and fertirrigation schedule. A soluble fertilizer with two contrasting doses resulting in 239 and 376 mg N per seedling was applied during the whole culture period. Seedlings grown under the highest level of fertilization had greater root collar diameter, height, shoot to root ratio, root and shoot mass, and root growth potential before planting. Post-planting performance was assessed at two sites in the Valsain Forest (Central Mountain Range, Segovia, Spain). In each site, seedlings from both fertilization treatments were planted in three plots with contrasting light environment (full sunlight, and under <em>Pinus sylvestris</em> stands with moderate and deep shade conditions). Survival, diameter and height growth were monitored for six years.</p><p><em>Main results:</em> Nursery fertilization did not affect survival, but high fertilization enhanced post-planting growth. Survival was highest under deep shade conditions but growth in this microsite was lower than in higher light sites, revealing a trade-off for survival and growth across light levels.</p><p><em>Research highlights:</em> The lower fertilization rate used in this study was suitable to produce seedlings with acceptable quality. Planting under shaded conditions (light availability&lt;30%) is recommended to maximize the initial success of yew plantations in Mediterranean mountains.</p><p><strong>Keywords: </strong><em>Taxus baccata</em>; plant quality; field growth; survival; reforestation.</p>