Leaf Morphological and Nutrient Traits of Common Woody Plants Change Along the Urban–Rural Gradient in Beijing, China

An increasing number of studies have found differences in the diversity of plant functional traits between urban and rural sites as a result of urbanization. However, the results remain inconsistent. In this study, we measured morphological and nutrient traits of 11 common woody plants along a continuous urban–rural gradient in Beijing, China. Leaf size (e.g., length, width, and area), specific leaf area, and leaf nitrogen and potassium contents decreased gradually and significantly along the urban–rural gradient, indicating that urbanization can enhance the capacity of plants to acquire resources for growth and production. Furthermore, soil nutrients and air temperature decreased along the urban–rural gradient, while air relative humidity increased. A structural equation model showed that these alterations in physical factors attributable to urbanization contributed directly or indirectly to changes in leaf functional traits, implying that changes in soil nutrients and micro-climate induced by urbanization may affect plant growth and production because of the improvement in resource acquisition capacity.

Genotype-Dependent Tipburn Severity During Lettuce Hydroponic Culture Is Associated with Altered Nutrient Leaf Content

Cultivated lettuce (Lactuca sativa L.) is one of the most important leafy vegetables in the world, and most of the production is concentrated in the Mediterranean Basin. Hydroponics has been successfully utilized for lettuce cultivation, which could contribute to the diversification of production methods and the reduction of water consumption and excessive fertilization. We devised a low-cost procedure for closed hydroponic cultivation and easy phenotyping of root and shoot attributes of lettuce. We studied 12 lettuce genotypes of the crisphead and oak-leaf subtypes, which differed on their tipburn resistance, for three growing seasons (Fall, Winter, and Spring). We found interesting genotype × environment (G × E) interactions for some of the studied traits during early growth. By analyzing tipburn incidence and leaf nutrient content, we were able to identify a number of nutrient traits that were highly correlated with cultivar- and genotype-dependent tipburn. Our experimental setup will allow evaluating different lettuce genotypes in defined nutrient solutions to select for tipburn-tolerant and highly productive genotypes that are suitable for hydroponics.

Principal component (PCA) and cluster analyses for plant nutrient traits in baby corn (Zea mays L.)

The present study was conducted to evaluate the plant nutrient traits in 12 baby corn genotypes by using Principal component analysis and cluster analysis during rabi 2017. Analysis of variance depicted the genotypes differed significantly among themselves for all the traits except sugar content. Variability studies revealed that PCV was observed maximum for all the traits. Maximum GCV and PCV were recorded for yield without husk followed by iron content and sugar content. Medium heritability was observed for all the traits except sugar content. Calcium content and iron content was recorded for highest genetic advance. Principal component analysis revealed that the first three principal components together accounted for 87.49 % of variability. The principal components (PC1, PC2) were highly positively influenced by sugar and iron contents, respectively. PC3 was negatively influenced by yield without husk. The 12 genotypes were grouped into three distinct clusters. The cluster-I were the largest cluster comprising of five genotypes and followed by Cluster-II (4 genotypes) and cluster-III (3 genotypes). The genotypes in cluster-I has higher iron content and yield without husk, while the genotypes in cluster-II having higher potassium, phosphorous and calcium contents. The genotypes in cluster-III exhibiting higher means for sugar and phosphorous contents.

Co-ordinated performance of leaf hydraulics and economics in 10 Chinese temperate tree species

Exploring relationships between leaf hydraulics and economic traits is important in understanding the carbon–water coupling and in extending the leaf economics spectrum. In this study, leaf hydraulics, photosynthesis, structural and nutrient traits and photosynthetic resource use efficiency were measured for 10 temperate tree species in the north-eastern China. Leaf hydraulic conductance was positively correlated with photosynthetic traits, specific leaf area, leaf nitrogen concentration, photosynthetic water and nitrogen use efficiencies, suggesting co-ordination between leaf hydraulics and economic traits. Principal component analysis revealed that significant correlations existed among leaf hydraulic, photosynthetic and resource use traits (axis 1), and axis 2 was strongly associated with leaf structural and nutrient traits. The 10 species were distributed along the diagonal line between axis 1 and axis 2. Species displaying the ‘fast’ strategy tended to have higher photosynthetic rates, leaf hydraulic conductance and photosynthetic water and nutrient use efficiencies; however, they also had lower carbon investment and faced a greater risk of embolism. These findings indicate that leaf hydraulics, economics and resource uses together play an important role in determining species ecological strategies, and provide supports for the ‘fast–slow’ leaf economics spectrum.