The decline in fossil fuel reserves has forced researchers to seek out alternatives to fossil fuels. Microalgae are considered to be a promising feedstock for sustainable biofuel production. Previous studies have shown that urea is an important nitrogen source for cell growth and the lipid production of microalgae. The present study investigated the effect of different concentrations of urea combined with kelp waste extract on the biomass and lipid content of Chlorella sorokiniana. The results revealed that the highest cell density, 20.36 × 10⁷ cells⁻¹, and maximal dry biomass, 1.70 g/L, were achieved in the presence of 0.5 g/L of urea combined with 8% kelp waste extract. Similarly, the maximum chlorophyll a, b and beta carotenoid were 10.36 mg/L, 7.05, and 3.01 mg/L, respectively. The highest quantity of carbohydrate content, 290.51 µg/mL, was achieved in the presence of 0.2 g/L of urea and 8% kelp waste extract. The highest fluorescence intensity, 40.05 × 10⁷ cells⁻¹, and maximum total lipid content (30%) were achieved in the presence of 0.1 g/L of urea and 8% kelp waste extract. The current study suggests that the combination of urea and kelp waste extract is the best strategy to enhance the biomass and lipid content in Chlorella sorokiniana.

The outcrossing traits in rice (Oryza sativa L.) affect the yield of hybrid seed production. Using a cytoplasmic male sterile (CMS) line with good outcrossing traits, such as short flag leaf length (FLL), narrow flag leaf width (FLW), wide flag leaf angle (FLA), and elongated panicle neck length (PNL), for hybrid rice seed production, it is possible to avoid the procedure of cutting flag leaves and make the supplementary pollination feasible by machine. In this study, a japonica restorer C-bao as the receptor parent and a primitive japonica accession Ludao as the donor parent were used to construct a chromosome segment substitution line (CSSL) population. The CSSL population was used to detect quantitative trait loci (QTLs) for the four outcrossing traits using a likelihood ratio test based on the stepwise regression (RSTEP-LRT) method. The CSSL population constructed consisted of 163 lines covering 90.7% of the donor genome. Among the seven QTLs detected in the CSSL population, four QTLs were detected in both years. qFLL-4 explained 6.70% of the two-year-averaged phenotypic variance, and the alleles from Ludao decreased FLL 5.1 cm. qFLA-1.1 and qFLA-1.2 explained 7.85% and 21.29% of the 2-year-averaged phenotypic variance respectively, and the alleles from Ludao increased FLA 17.38° and 31.50°. qPNL-8 explained 8.87% of the 2-year-averaged phenotypic variance, and the alleles from Ludao increased PNL 4.44 cm. These favorable alleles identified could be used to improve the outcrossing traits of parents for hybrid rice seed production in rice.

Microalgae have been investigated for the production of different biofuels, and the feedstock is gaining interest in the present day due to their fast growth potential added to relatively high lipid, carbohydrate, and nutrient contents. The purpose of this study is to perform research to grow commercial microalgae and to produce a significant amount of lipid content from microalgae harvested as a viable alternative to renewable energy. The commercial microalga chosen is Chlorella sorokinian. Nitrogen is an essential element for microalgal growth, lipid synthesis, and several physiological processes. Microalgae can utilize several nitrogen sources, including nitrate and ammonium. The growth and lipid content of microalgae cultures and their biochemical structures are influenced by the type of nitrogen utilized, which is contingent upon the specific species of algae and the quantities and sources of nitrogen. This study aims to increase the growth and lipid accumulation of the microalga Chlorella sorokiniana by varying the nitrogen sources NaNO3, KNO3, and NH4Cl concentration in the culture medium. Results indicate that the highest cell density of 28.83 × 107 cell mL-1 and the maximum 4.1 g L-1 dry biomass were obtained under the treatment of sodium nitrate. Among nitrogen sources, the better pigment contents chl a 17.2 mg L-1 and chl. b contents were recorded in the case of sodium nitrate, followed by potassium nitrate and ammonium chloride. However, carbohydrate production was found to be a maximum of 390.1 μg mL-1 in ammonium chloride culture. The lipid content was measured using the Bligh and Dyer method and observed the highest 19% in sodium nitrate culture compared to other nitrogen sources. Overall, it can be concluded that sodium nitrate culture produced promising results regarding biomass production and different biochemical attributes.