Nitrogen Fertilization Effects on Physiology of the Cotton Boll–Leaf System

The objective of this study was to assess the impacts of nitrogen on the physiological characteristics of the source–sink system of upper fruiting branches under various amounts of nitrogen fertilization. A two-year field experiment was conducted with a Bt cotton cultivar in the Yellow River Basin of China. The growth and yield of cotton of the upper fruiting branches were compared under four nitrogen levels: Control (N0, 0 kg ha−1), low nitrogen (N1, 120 kg ha−1), moderate nitrogen (N2, 240 kg ha−1), and high nitrogen (N3, 480 kg ha−1). The results indicated that in the subtending leaves in upper fruiting branches, chlorophyll content, protein content, and peroxidase (POD) activity dramatically increased with nitrogen application, reaching the highest under the moderate nitrogen treatment. The physiological characters in the seeds had the same trends as in the subtending leaves. Furthermore, the moderate nitrogen rate (240 kg ha−1) had a favorable yield and quality. Our results supported that a moderate nitrogen rate (240 kg ha−1) could coordinate the source–sink growth of cotton in the late stage, enhance the yield and fiber quality, and decrease the cost of fertilizer in the Yellow River Basin of China and other similar ecological areas.

Two new species of Burmeistera (Campanulaceae: Lobelioideae) from Antioquia, Colombia

Burmeistera fistulosa and B. reclinata, both from the department of Antioquia (Colombia), are here described and illustrated. The first species is similar to B. tomentosula, from which it differs by the glabrous surfaces, the petiole 1.4–2 cm long, the lamina elliptic to ovate, the reduced subtending leaves, the calyx lobes 2.5–3.5 x 0.8–1.2 mm, the ventral anthers barbate, and the white, obconic to ellipsoids berries. The second species is similar to B. diazii, from which it differs by the narrowly ovate leaves with 5–6 pairs of secondary veins and higher order veins inconspicuous beneath, the glabrous flowers with calyx lobes 5–9 x 0.6–1 mm, half of the corolla length or less, the barbate ventral anthers, and the white berries suffused with vinaceous lines.

Evolution of cyme architecture in Celastraceae

Celastraceae are characterized by a cymose pattern of inflorescence ramification. Under this basic pattern, many inflorescence forms have been described within the family, e.g., dichasium, monochasium, pleiochasium, botryoid, thyrsoid, fascicle. Thus, the question has arisen—how have these varieties evolved or transformed from one to another? Through morphogenetic observations using paraffin sections, scanning electron microscopy (SEM), and stereomicroscopy, we studied the architecture and developmental processes of the inflorescences of five species of Celastrus and Euonymus. We found in C. orbiculatus that the reduction of subtending leaves of the axillary dichasia on a developing flowering shoot made it become a terminal thyrsoid. A dichasium in the leaf axil as commonly seen in Euonymus is the most frequent type of inflorescence in Celastraceae. An analysis of character evolution suggested that a dichasium is the ancestral state for Celastraceae. Therefore, within Celeastaceae, an axillary dichasium may be the basic type or unit of inflorescences. Transitions from dichasium to thrysoid and other types of cymes, and even to solitary flowers might have occurred repeatedly in the family, probably a phenomenon of evolutionary convergence due to changing environmental conditions. The present study provided helpful information for understanding the evolution of the cymose type of inflorescence in flowering plants.