Growth Effect of Biennial Seedlings of Half-sib Families of Cyclobalanopsis glauca

The seedling height and ground diameter of 42 half-sib families of biennial Cyclobalanopsis glauca were investigated and compared. The results showed that there were extremely significant differences between different families in the terms of seedling height and ground diameter. According to the seedling height and ground diameter, families 39, 27, 28 and 19 of C. glauca were superior to other families at the seedling stage.

Determination of Optimum Seed Rate of Hybrid Rice (Oryza sativa L.) Varieties in Mat-Type Seedling Raising for Mechanical Transplanting

Rice is the most important and crucial to ensuring food and dietary energy security in most developing countries and is the staple food of more than half of the world’s population. This study was conducted to identify the seed rate of hybrid rice varieties for mechanical transplanting during Boro (irrigated dry season), 2021-22 season at BRRI research field, Gazipur. Slender grain type BRRI hybrid dhan3, BRRI hybrid dhan5, Ishpahani hybrid dhan6, and BRRI dhan89 were used in the study. The same growth medium was used to establish mat-type seedlings on plastic trays (280 × 80 × 25 mm) at seed rates of 80, 90, 100, 110, and 120 g∙tray−1. Walk-behind type 04 rows rice transplanter (Daedong, model-DP 488) was used during transplanting in the field at the set of the plant to plant spacing of 140 mm while line-to-line spacing was fixed to 300 mm. The result depicted that regardless of the variety, seedling density increased linearly as seed rate increased, except for the 21 days following sowing. However, the seedling density of BRRI dhan89 decreased after the seed rate of 100 g∙tray−1 due to mortality. The seedling height of the BRRI hybrids dhan5 and Ishpahani hybrid dhan6 was significantly higher than that of the BRRI hybrid dhan3 and BRRI dhan89. After 21 days, the seedling height decreased significantly with the increase in seed rate. For the seed rates of 100, 110, and 120 g∙tray−1, identical numbers of hills per unit area and plants per hill were observed. On the other hand, regardless of the variety, the percentage of missing hills considerably decreased with the increased seed rate. The yield of the BRRI hybrid dhan5 variety was significantly higher at the seed rates of 100 and 110 g∙tray−1, although the yield of the Ishpahani hybrid dhan6 variety was comparable. In terms of yield among the four varieties, BRRI hybrid dhan5 gave a higher yield followed by Ishpahani hybrid dhan6 while BRRI dhan89 gave a lower yield compared to the hybrid varieties irrespective of the seed rate. However, a seed rate of 110 g∙tray−1 gave a significantly higher yield followed by 120 g∙tray−1 while 80 and 90 g∙tray−1 gave lower grain yield. Generally, mat type seedling of inbred rice varieties is used in Bangladesh. The determination of seed rate of hybrid rice varieties may be increased by the use of rice transplanter in mechanical transplanting of hybrid rice varieties reducing the seed loss and increasing the grain yield.

Preliminary Study on Optimized Conditions for Dry-cultivated Rice Seedling Planting

The effects of soil moisture content, pot seedling buried depth, and pot seedling height on the survival rate and growth of dry planted seedlings were researched by field experiment. The results showed that the seedling survival rate and growth were enhanced with the increase of soil moisture content after pot seedling transplanting, but there was no significant difference in the survival rate and growth of seedlings with 85% and 100% of soil moisture content. Pot seedling buried depth was one of the important factors affecting the survival rate, and when the pot seedlings were buried 2 cm deep, the seedlings showed high survival rate and excellent growth. Under the same condition of soil moisture content and buried depth, seedlings with pot seedling height of 15 cm had the best survival rate and growth. Therefore, the optimized conditions for dry-cultivated rice seedling planting were soil moisture content of 85%, pot seedling buried depth of 2 cm, and pot seedling height of 15 cm.