Growth Analysis on the Plant Type Peanut Varieties, Arachis hypogaea, L. : I. Varietal difference and seasonal change of total leaf number and area of peanut individuals differing the plant type grown under various field conditions

Abstract

Since 1962, this study have carried out to clarify a significance of difference of the plant type as the productive structure and qualitative characteristics of assimilation system in peanut varieties under various field conditions. Four cultivated varieties typically differing the plant type, i. e., erect, Spanish type (E 1, E 2); semi prostrate or intermediate, Virginia Bunch type (SP); prostrate, Virginia Runner type (P); were used in the present experiments (tab. 1). In this paper, difference among 3 plant types and seasonal changes of the leaf amount of individuals obtained in 1962, 1964, and 1965 was described. Results and discussions are as follows: 1. In all varieties, total number of leaves per plant showed an exponential rapid increase from ca. 3 weeks after seeding till the maximum leaf amount stage, middle of August, ca. 90∼100 days after seeding. Rate of leaf production during such a period, however, differed with spacing, amount of nitrogen fertilized, and the plant type. That is, rate of leaf production was high in order of P, SP, and E. And response in leafiness for the nitrogen fertilization seemed to be characteristic of the plant type (fig. 1). 2. A positive close relationships was observed between the maximum values of total number of leaves per plant and that of branches in each of the varieties. 3. Total leaf area per plant showed the same seasonal change (fig. 2). Degree of varietal difference in the maximum value, however, became smaller than that in total number of leaves, due to both of the varietal differences in size of single foliage leaf (E>SP≒P) and in range of its seasonal variation (E>SP≒P) (figs. 3 and 4, tab. 2). Maximum values of total leaf area per plant were: E, 0.5∼1.5, SP, 0.4∼1.6, and P, 0.7∼2.0 m2/ plant, respectively. And values of L.A.I. (total leaf area/ground area/plant) were 4∼5 in E and SP, but in 1962 and 1964, 8∼9 in P. 4. Vertical distribution of dry matter weight of leaves and compactness in leafiness were also higher in P (fig. 5). Lower and denser leafy characteristics of canopy in prostrate varieties are apt to make worse the productive structure than the taller and sparse leafy varieties, E and SP (tab1e 3). 5. Very low proportion of main stem's-leaves which occupied in total leaf area of individuals, particularly, in SP and P, was observed through almost of growth period, except til1 2∼3 weeks followed the developing stage of the embryonic leaves (fig. 6). The role and contribution of main stem and its leaves for the establishment of assimilation system and dry matter production in this crop was interested. 6. Since the period of the maximum leaf amount corresponds to so-called limiting period of effective flowering for fruit maturing in our country, it may be suggested that the early establishment of canopy architecture and keeping of optimal leaf amount, especially in prostrate varieties, are of very important to increase dry matter production and fruit yield of peanut. 7. Based on the leaf amount and branching behavior, 3 canopy types were distinguished as follows : E : Sparse leafy type; P : Dense leafy type; SP : Intermediate leafy type. 8. It was suggested that the semi-prostrate or intermediate plant type of varieties would be the most profitable considering the productive structure among cultivated peanut varieties.