Exploring Subtropical Grasses Adapted to Low Temperature from Asian Countries
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Exploring Subtropical Grasses Adapted to Low Temperature from Asian Countries By SUKEO KAWANABE Grassland Planning Division, National Grassland Research Institute candensatus are distributed only in the south Species ecology of native grasses ern area, the former has been distributed in in Japan the subtropics while the latter has developed its distribution in the southern warm tem Japan is situated in the middle of the north perate zone. The former is regarded as the latitue and belongs to the Asian monsoon ancestor of the many species of genus climatic zone. Miscanthus (Lee 1964) . M. floridulus is an A mixed up aspect of northern element evergreen species and M. condensatus is a half with the southern one can be observed on the evergreen species. All other Miscanthus sp. grasses of this country in the same way as are of summer green. cold current meets with the warm one around The fact that many of the annual grass the Japanese mainland. species of the southern element are distributed' The southern element (Miscanthus, Zoysia in the northern area, and the relation between etc.) is sweepingly dominant over almost the the distribution and phenological type men area of Japan, while the northern element tioned above suggest as follows; that is, most (Sasa, Calamagrostis etc.) is dominant over of the southern element species have no the northern area of the island of Hokkaido. tolerance for cold weather and are confined Here subfamily Panicoideae and Eragros to the tropics and subtropics, but a few of toideae are designated as the southern element, the species have acquired the adaptability for and the species of Festucaideae is designated low temperature and developed its distribution as the northern element (Kawanabe 1968). to the northern area in Japan. Among the southern element, a few of the genera or species originated in the tropics Cultivated grasses in Japan or subtropics of Asia had been adapted to low temperature and might have developed Sown grasslands in Japan can be roughly their distribution to the north of the Japanese classified into two types; one is paddy or mainland. upland field where annual grasses have been Genus Miscanthus to which Mi.scanthus cultivated mostly in short rotation, and the sinensis belongs will be discussed hereunder other is the permanent pasture of hilly land as a representative species in the Japanese where perennial grasses have been cultivated. grassland. As for the annual grasses, Lolium multi This genus seems to have been derived from floru1n (Italian rye grass) has been much genus Saccharum which distributes in the cultivated. Chlories gayana, a perennial grass tropics. Among six .species of Miscanthus in the tropics, has been cultivated as an distributed in Japan, M. floridulus and M. annual grass and recently the test cultivation 112 JARQ Vol. 8, No. 2, 1974 of Eleusine indica var. Coracane and Paspalum be the cause that native grass cannot give clistichiim was carried out. good result. And the fact that species grown As for the perennial grass, the temperate in a certain environment is not the only one grass such as Dactylis glmnercitci ( orchard which is most adaptable to that environment grass) and Fertuca arundinacea (tall fescue) also js a good reason for the important intro are the majority, and the subtropical grass duction (Kawanabe 1967) . such as Paspaliim clilcitatum (Dallis grass) is Even the species, which possesses the poten cultivated only in a small area. tial to grow up in an environment, could not In southern Japan, the decline of summer grow in that environment because of its production, the shortening of persistency; distribution prevented by isolation. This can namely, the damage of summer depression are be substantiated the existence of many cosmo unavoidable for temperate grasses which be politan varieties of weeds or ruderals which long to the group of the northern element had been distributed widely according to the described above. Growing the grasses, which development of communication and transporta belong to the northern group, in the area tion, and isolation may be clarified by geohis where the southern element is dominant seems tory. vet·y rare. Fm-thermore the temperate grasses, which Experiments on the responses of originated in the Mediterranean region and subtropical grasses against low have been bred in Europe and America are tempe1~ature cultivated in Japan while the species originated in Japan which are not used utterly must be Low temperature adaptability is always the very rare. Some Japanese ecologists criticized first ta1·get for the exploration of perenniaJ such present situation from the point of view or annual grasses which are suitable for culti that the indigenous species are most adaptable vation in the warm regions of Japan. As to the land. to the low temperature adaptability, there are two points to be considered, one is the Significance of the introduction of good growing ability in low temperature region subtropical grasses and the other is winter survival. The former is needed for annual grasses and the latter Some examinations on indigenous grass had is especialJy necessary for the perennial. been made in Japan. A certain effort had These two characters are incompatible with been made on the cultivation of Miscanthus each other, for example, in M eclicags sativ<£ sinensis (Susuki), Puernrici Thunbergiana (Alfalfa) , the winter hardy variety is suitable (Kuzu). and Lespecleza bicolor (lfagi) etc. for cultivation in cold area but its growth But the difficulty of the multiplication by seeds, declines soon in autumn and comes into short growing period, low increase rate of dormancy, while non-hardy variety which is yield in response to fertilizer and low ablity suitable for warm region shows a contrary of regrowth after cutting or grazing are the trend. common defects of these plants. An example of the study on the low tem Though it is not so much as the case of perature adaptability with respect to Chloris general crop plants, the cultivation environ gaynnci and Setnria svhacelata which orginated ment of grass is greatly different from the from different altitudes is introduced here natural one, that is, f ertilizer is applied, cut under (Neal-Smith C. A. and S. Kawanabe). ting and grazing are repeated and sometimes soil is turned over with plough. No species 1) Chl01·is ga11cinci of grasses grown in natural environment can This is the grass originated in East Africa adapt to such artificial environment. This may and is suitable for , cultivation in warm 113 Table 1. Origin and growth form of cultivars of Chloris gayana Cultivar Origin Altitude (m) Growth form The natural, unselected variety from 1.170 Stemy Serere Serere reserch station, Uganda Mpwapwa Detected near Iringa, Tanganyika I. 730 Leafy A diploid variety of suspected Leafy Nzoia S. African origin, First recorded near Kitale 2.000 Mosaba A variety from Endebess, Kenya 2. 270 Stemy region. Growth under low temperature in the day length and temperature are scarcely phytotron was compared with four cultivars variable through out the year because this from Kenya and one Australian commercial area is situated just under the line, but diurnal variety (Table 1). range is very large. In the area of the maxi The maximum distribution limit in altitudes mum distribution limit in altitude, the mean of this grass is 2,700 meters in Kenya, but value of daily maximum temperatures seems the majority is found in altitudes below 2,000 to be 21 to 22•c, and that of daily minimum meters. temperature may be 4 to 5°C. Summer is not As to the climatic condition of this area, so hot and winter is not so cold. The climate is very mild. Fig. 1 shows the relative growth rate (RGR) of young plants of each cultivar grown in the plytotron under the temperature of 15• / 10°, . 35 ... ~~o 18°/13° and 21°/16° (day/night ·c). RGR of // commercial vai·iety and that of Nzoia and Mosaba both of which originated in high ~/ .25 altitude are higher than those of Serere and ... /."' Mpwapwa which originated in low altitude. I~ The grasses grown under the temperature .20 ~,If of 15°/l0°C had pale green leaves and showed very little growth because this temperature ;J was the minimum limit for the growth of subtropical grasses. The cultivar originated .15 / /J • Serer< 1 / ft 1 0 M1)w11pwa in high altitude, however, showed fairly good growth. Clausen et al. (1948) have revealed /? A M osnbo that there is a close relation between the . 10 D Commc1·cial climate of habitat and the temperature re /// sponse of the plant grow11 there. This principle X I 0 / can be applicable to the grasses too. I I .05 0 2) Setaria sphacelata • T his grass has not been cultivated in Japan but it is an important species in Australia. 01'--~-----~-----~- This genus is an interesting source for ex 15/10 18/ 13 it/ 16 ploration because many differentiations of clay/night temperature ( ° C) this genus can be found in crop plants and weeds. Fig. 2 shows field comparison of the Fig. 1. Comparison of relative growth rate of five cultivars in Chloris gayana originat winter survival and yield among five val'ieties ed from varied altitudes originated from different altitudes. 114 JARQ Vol. 8, No. 2, 1974 Name on Drr weight g/plnnt Winter survival % Species nhiludc of origin .... l'v 0 0 1¢,f;l,.O')(.O 0 or--~- ~<>--.---,<>i-_ o o o o o -0 Kazungula 3330m Se/aria sphacc/ala 2980 2930 2900 Paspal1m1 dilalnl111n 5% L.S.O 1%L.S.D Fig. 2. Dry weight and winter survival of five varieties of Setaria sphacelata, comparing with Paspalmn dilataltun This grass also grows naturally in Kenya more step into the study on the introduction.