Molecular Dissection of Relationship Between Seedling Characteristics and Seed Size in Rice

Seedling characteristics such as leaf emergency, chlorophyll content, and height are important for early growth and also associated with seed size. Quantitative trait loci (QTLs) for rice (Oryza sativa L.) seedling characteristics (leaf length, chlorophyll content, seedling height) and seed size were identified with an attempt to explore the relationship between seedling characteristics and seed size, using a recombinant inbred population derived from a cross between Zhenshan 97A and Minghui 63. Two, one, five, four, four, and nine QTLs were detected for chlorophyll a content, total chlorophyll, length of the second seedling leaf, length of the third seedling leaf, seedling height, and seed size, respectively. The results indicated that four QTLs for seed size and four QTLs for seedling characteristics shared several similar regions (G359-RG532, C567-RG236, RZ403-R19, C371-C405a), respectively, suggesting a close association between seedling characteristics and seed size. Several chromosomal regions influencing seed size, however, had no effects on seedling characteristics, suggesting that it was possible to improve seedling vigor without increasing grain size.

Growth Performance of Phoebe bournei Generations in Seedling Stage

[Objective] The aim was to explore growth performance of Phoebe bournei in seedling stage.[Method] Based on 17 superior plus trees of Phoebe bournei,a seedling cultivation test was conducted in Jindong Forest Farm in Yongzhou,Hunan Province,exploring growth indices and analyzing seedling height and ground diameter.[Result] As per the selection rate at 20％,PB17,PB9 and PB12 were selected from the 17 species.Specifically,the seedling height averaged 36.52 cm of the selected three seedlings,which was higher by 16.1％ compared with average of 17 species （31.45％）.As for ground diameter,the selected species averaged 2.6 mm,which was higher （13.0％） compared with the average level （2.3 mm）.[Conclusion]Both of seedling height and ground diameter reached extremely significant differences,which indicated that half-sib families of Phoebe bournei have rich variations,with selection and breeding potential.

Germination and Survival of Maize and Beans Seeds: Effects of Irrigation with NaCl and Heavy Metals Contaminated Water

Metal toxicity and soil salinity at excessive levels in soils are toxic to plants. The main objective of this study was to demonstrate the effects of water salinity (NaCl) and heavy metal concentration on germination and seedling characteristics of maize and beans seeds. Different concentrations of NaCl (0 to 35000 mg/L) and Zn2+, Cu2+ and Pb2+ with concentrations 0 to 600 μmol/L each were used separately. These solutions were used to irrigate maize and bean seeds for 30 days. Data was taken daily for the following parameters;“the number of germinated seeds, shoot length, shoot circumference, leaf area index, leaf colors, senescence, and disease occurrences.” The crops were uprooted at the end of the 30 days and their wet masses were measured and recorded. Results indicated that seed germination reduced with an increase in the concentration of NaCl for both maize and beans with 0% germination recorded in concentrations > 5000 mg/L. The same trends were observed for other parameters, the shoot length, the leaf area index, and the shoot circumference. “For heavy metals, the trends were similar. Beans growth was more affected by Zn and Cu but maize growth was more affected by Pb.” The dry masses and wet masses of the crops with higher concentrations of metals and salts were very low compared to the control experiments. For the effects of salinity and heavy metals on beans and maize seeds, there was a significant difference (P ≤ 0.001) between all tested concentrations and the control for all growth parameters monitored. It was concluded from the results that salinity and heavy metals affect the germination and seedling characteristics of maize and beans;though some metals are essential, their presence in higher concentrations instead cause harm.

Responses of Caryopsis Germination, Seedling Emergence, and Development to Sand Water Content of Agropyron cristatum （L.） Gaertn. and Bromus inermis Leyss.

Responses of caryopsis germination, seedling emergence, and development of Agropyron cristatum （L.） Gaertn. （Gramineae） and Bromus inermis Leyss. （Gramineae）, two dominant perennial grasses in the Otindag Sandland of China, to different sand water content （SWC; 1%, 2%, 3%, 4%, 6%, 8%, 12%, 16%, and 20%） were studied comparatively. The results showed that the germination responses of the two grasses to SWC were similar （i.e. caryopses could not germinate when the SWC was below 3%; at SWC ranging from 3% to 12%, the higher the SWC, the higher the germination percentage; and at a SWC of 12%-20%, germination reached similarly high percentages）. At a sand burial depth of 0.5 cm, the threshold of SWC for seedling emergence was 6% forA. cristatum and 8% forB. inermis; at 12%-20% SWC, the seedling emergence of both species reached similarly high percentages. The seedling growth responses of these two species to SWC gradients were different. For A. cristatum, the biomass of seedlings increased with SWC from 6% to 12%, and decreased with SWC from 12% to 20%. For B. inermis, the biomass of seedlings always increased with SWC from 8% to 20%. The results also showed that the seedlings of both species allocated more biomass to the roots with decreases in SWC. The SWC changes from April to October in natural microhabitats of both species suggested that the SWC may play an important role in caryopsis germination, seedling emergence, and the growth characteristics of the two grasses. The responses of caryopsis germination, seedling emergence, and the growth characteristics of these two species to SWC may determine their distribution pattems in the Otindag Sandland.