Growth Analysis on the Plant Type in Peanut Varieties, Arachis hypogaea, L. : Varietal difference in pattern and enlargement of coverage of canopy differing plant type grown under the non-competitive condition

[摘要] It may be mentioned that the non-competitive condition where free space being given is required to observe correctly morphological development of peanut canopies differing plant type. Then, we will be able to avoid morphological growth distortions caused by competitive effects with the adjascent individuals in crop community. The present experiments were carried out based on the above mentions to obtain some informations on varietal difference in horizontalcanopy expansion-ability. Five Virginia type (P1, P2, P3, SP1, and SP 2) and one Spanish type (E) varieties and 2 plants per a variety were used (tab. 1). 0n May 22, two disinfected seeds were sown into the center of a wooden bottomless frame buried in land: 100 × 100cm and 50cm in depth, and before seeding, 3.2, 8.3, and 12.2g/m2 of N, P2O5, and K2O, respectively, and at the early blooming period, 3Og/m2 of CaO were given: and then seedlings were thinned to single stand after germination. Photographs of projected area of canopies on land surface were taken half-monthly, and cutouts of their prints were weighed to calculate the coverage in per cent for the frame area, 1m2. Results obtained and discussions are as follows: 1. Characteristic pattern and successive enlargement of coverage were observed in each of variety owing to difference in plant type, branching behavior and vegetative growth rapidity (figs. 1, 2 and 7). Rapidity shown by the number of days to reach both 50%- and l00%- period in coverage was high constantly in order of P1>P3>P2>E>SP 1≒SP 2 (fig. 3). Under this experimental condition, variety E showed a large canopy expansion-ability in coverage and foliage amount, but, it must be noticed an influence upon coverage by lose of erectness of lower primary branches, which makes the plant almost as procumbent like the prostrate varieties after middle growth period (fig. 3). 2. Among 3 prostrate varieties, P2 showed a characteristic sparse branching habit like "trailing type" with the slowest development of canopy and low foliage yield, and, contraly, P3 showed the largest canopy growth in the last value of coverage and foliage yield among all of varieties (figs. 3 and 7 tab. 2). 3. The maximum values of rate of rate of coverage increase which appeared in August in each of variety, were 0.15∼0.4m2/ 10 days, and during this 30 days the coverage corresponds to about 40∼55% of the last size increased by such vigourous growth (fig. 4). 4. Very high correlation (r=+0.972) between length of cotyledonary laterals and coverage was obtained (figs.5 and 6), and the importance of these laterals not only in fruiting but as the basic skeleton of stem-system and canopy expansion in this crop was recognized. 5. Horizontal and vertical distribution of vegetative and reproductive parts at harvesting time were also characteristic with the plant type of variety (figs. 8 and 9). 6. Thickness and compactness and also the expanding rapidity in coverage of canopy are of important characters particularly in choosing of the variety best adapted for covering ground, forage and green manure purposes in this crop.

[学科分类] 农业科学（综合）