19, 4 Reinking and Groff: Siamese Seedless Pummelo 409 
has thus become a labyrinth of beds and ditches across which 
one can pass with difficulty, either on narrow logs thrown across 
from bed to bed (Plate 7, fig. 2) or by hurdling the trenches. 
PLANTING 
The pummelos are not planted for at least five years after an 
inclosure is first plotted. This allows time for the raising and 
settling of the beds, the decay of organic matter in the newly 
cleared land, and the planting of some preliminary growth for 
shade. In well-planted orchards the young trees are eventually 
set out in the center of the beds with more or less irregular 
distances of from 3 to 4.5 meters between the trees. By the time 
the trees reach their most productive age, the constant deepen- 
ing and widening of the trenches has reduced the width of the 
beds to at most 4.5 meters, and the ditches between them to a 
width of from 1 to 2 meters. The depth of the trench is now 
from 1 to 2 meters from the level of the bed. 
SHADING AND INTERCROPPING 
Little scientific experimental work has been done on the effect 
of shade upon citrus plantings. That some shade is advanta- 
geous in citrus growing under tropical conditions is evident from 
the experience of native growers. In Nakorn Chaisri there 
seems to be considerable intercropping, partly with the view to 
providing shade; and numerous trees of other species are found 
planted, sometimes with uniformity and sometimes at random 
in the groves. The coconut palm (Cocos nucifera Linn.), the 
betel palm (Areca catechu Linn.), and the banana (Musa sapien- 
tum Linn.) are the chief plants used. Betel palms are perhaps 
the most conspicuous in Nakorn Chaisri, and the trees are said 
to be very profitable. They seem to thrive under this raised-bed 
system of cultivation, and trees are often found growing along 
the edge of citrus beds (Plate 7, fig. 3). These are doubtless 
established some years before the pummelos are planted, and 
the center of the beds is left open for the citrus. Banana plants 
are often grown between the betel palms and the pummelos. 
In some of the other lowland regions of Siam, especially in 
Dao Kanong, a shade tree, Erythrina fusca Lour., known locally 
as thong lang, is grown especially to shade fruit trees and to 
Sweeten and enrich the soil. Some growers have so strong a 
belief in the thong lang as to maintain that successful fruit 
culture, under the raised-bed system of irrigation and drainage, 
