No abstract

Hoa Binh province is one of the best places for orchids in Vietnam. The climate and environment of Hoa Binh province are favorable for the development of orchids, especially rare indigenous ones. Dendrobium anosmum Lindl., which stands out because of the unique fragrance and colors, is one of the most popular varieties in Hoa Binh province. To meet the increasing demands of the industrial market as well as to contribute to the preservation and development of genetic resources of Dendrobium sp. in Hoa Binh province, propagating D. anosmum Lindl. is a crucial step. Plant tissue culture, which has been applied to improve reproducibility of orchids for many years, is still an effective method, especially for large-scale propagation. Studies on in vitro propagation of D. anosmum Lindl. from Hoa Binh province showed that growth regulators (BA, kinetin, α-NAA) did not have a significant effect on protocorm initiation because D. anosmum Lind. from Hoa Binh province already has a high rate of regeneration. However, MS medium + 1.0 mg/L kinetin + 0.5 mg/L α-NAA + 30 g sucrose + 8.0 g agar per liter, pH 5.7–5.8 was the optimal medium to increase shoot length. The MS medium + 1.0 g activated charcoal + 30 g sucrose + 8.0 g agar per liter, pH 5.7–5.8 was the most suitable medium for shoot growth—after 6 weeks of culture, the average shoot length was 1.09 cm, the average number of leaves was 6.13, the average number of roots was 3.17, and the average root length was 1.11 cm—about 3.3, 4.17, 3.41, and 1.67 times higher, respectively, than in the control (without activated charcoal).

Avocado is a significant cash crop in Vietnam, while little is known about its genetic diversification. Random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers were performed to investigate the genetic diversity of twenty-eight imported and domestic avocado cultivars being maintained at Western Highlands Agriculture and Forestry Science Institute, Dak Lak, Vietnam. 18 RAPD and 15 ISSR primers produced 3183 and 2807 scorable bands, of which 83.92% and 71.72% were polymorphic, respectively. The RAPD markers exhibited an average PIC of 0.27 and Rp index of 12.63 whereas the mean PIC and Rp values of ISSR primers were 0.21 and 13.37, respectively. The correlation between RAPD and ISSR markers was low (r = 0.338), suggesting that the ability to resolve genetic variation among varieties may relate to the number of detected polymorphisms rather than the marker employed. Nevertheless, the correlation between ISSR and combined data was high (r = 0.791) and the correlation between RAPD and combined matrices was even higher (r = 0.897). This indicates that RAPD markers have slightly higher efficiency over ISSR to resolve genetic variation among 28 avocado cultivars. High genetic diversity among 28 avocado cultivars was revealed with the Jaccard’s similarity coefficient ranging from 0.623 to 0.913 based on combined data analysis. The UPGMA dendrogram generated from combined RAPD and ISSR data grouped Vietnamese domestic and imported avocado cultivars into three different groups at 72% similarity. These results could be applied to the avocado conservation and breeding programs

Nitrogen (N) deficiency is one of the most common problems in soils, limiting crop growth and production. However, the effects of N limitation in seedlings on vegetative growth remain poorly understood. Here, we show that N limitation in rice seedlings restricted vegetative growth but not yield. Aboveground parts were affected mainly during the period of tillering, but belowground parts were sensitive throughout vegetative growth, especially during panicle development. At the tillering stage, N-limited plants had a significantly lower N content in shoots, but not in roots. On the other hand, N content in roots during the panicle development stage was significantly lower in N-limited plants. This distinct response was driven by significant changes in expression of N transporter genes during growth. Under N limitation, N translocation from roots to shoots was greatly sped up by systemic expression of N transporter genes to obtain balanced growth. N limitation during the seedling stage did not reduce any yield components. We conclude that the N condition during the seedling stage affects physiological responses such as N translocation through the expression of N transporter genes.