การศึกษาขนาดและรูปร่างแปลงทดลองที่เหมาะสมของข้าวฟ่าง และการเปรียบเทียบประสิทธิภาพ ระหว่างแผนการทดลองแบบสุ่มในบล็อคสมบูรณ์ และแบบแลททิซ / เบญจพร นิรนาทกูล = A study on optimum plot size and shape for sorghum yield tests and relative efficiency between randomized complete block and lattice designs / Benjaporn Niranatkul
Two sets of Uniformity trial data were used to estimate the optimum size and shape of plot, to construct the soil fertility contour maps, to determine the block efficicncies, block shape and the efficiencies of simple lattice, triple lattice and lattice squares related to randomized complete block design. The trials were conducted, one at Thailand National Corn and Sorghum Research Center, Nakorn ratchasima province and the other at Takpha Experiment Station, Nakorn sawan province from August 1981 to February 1982. In both trials, KU.257 was used as the indicator variety, It was planted at 75×10 cm. spacing. Each trial, excluding border rows and end rows, was divided to 2,304 basic units of .75×1.0 m. in size. Each basic unit was harvested, treshed and weighed separately and grain yield was recorded in grams per basic unit. The conclusion of the study were as fallow : 1. Soil heterogeneity indices were found to be 0.3518 at Thailand National Corn and Sorghum Research Center and 0.4244 at Takpha Experiment Station. The indices indicated that the experi¬mental field at Thailand National Corn and Sorghum Research Center has higher correlation in soil fertility among adjacent plots than the experimental field at Takpha Experiment Station. 2. The optimum size of plot estimated by Smith's equation were about 6.0 square meters at Thailand National Corn and Sorghum Research Center and about 9.0 square meters at Takpha Experiment Station. 3. Plot shape did not appreciably effect plot variability and long and narrow shaped plot appeared practicable. 4. At Thailand National Corn and Sorghum Research Center, the fertility contour map showed a patchy fertility pattern but at Takpha Experiment Station there was a unidirectional fertility trend along the length of the field. 5. In all cases tested, the efficiency of blocking was measurable and was varied with block shapes. When the optimum sized was used and block size is small, the nearly square shaped block was better than the rectangular shaped block but when block size increased, the rectangular shaped block was found to be more practical. 6. Lattice designs were more efficient than randomized com¬plete block design. Lattice square, triple lattice and simple lattice had the efficiencies about 129%, 116% and 109% respectively in relation to randomized complete block design. From these figures it can be seen that lattice squares was the most efficient among the three lattice designs.