The Environmental and Social Costs of Improvement 33of calories derived from plants (FAO, 1993; Fowler and Mooney, 1990). The trend
has been rapidly downwards in many countries (Table 1.6). In India, once more
than 30,000 rice varieties were grown, but now just 10 cover 75 per cent of the
whole rice area. A comprehensive study of the decline in the US this century has
been conducted by Cary Fowler and Pat Mooney (1990), where ‘the losses of fruit
and vegetable varieties are staggering’. For 65 types of vegetable, they record a
consistent loss of between 80–100 per cent of the varieties of each since the turn
of the century. Of the 8207 varieties listed for these vegetables in 1903, only 607
are now held by the National Seed Storage Laboratory.
Most modern scientists have seen mixtures as a problem to be overcome. When
the Rockefeller-sponsored team first visited Mexico in the 1940s to assess wheat
cultivation as a precursor to establishing the national wheat breeding programme,
the low-yielding traditional fields were condemned because: ‘most fields were a
mix of many different types, tall and short, bearded and beardless, early ripening and
Table 1.5 Numbers of rice varieties and their qualities encountered in three non-
irrigated rice regions of MyanmarRegion Number of varieties Qualities of rice varieties
Rainfed uplands 18 115 to 180-day duration
red and white
glutinous and sticky
long and short awned and awnless
drought tolerant and intolerant
100–150cm in height
for eating or for rice wine
grain size
length of time in stomach
yields from 1.0 to 2.0t/ha
Deepwater rice 18 elongation from water
panicle in or out of water
expansion when cooked
eating quality
yellow and white
resistance to stem borer
yield from 1.5 to 1.8t/ha
Rainfed lowlands 16 125–200 day duration
flood or drought tolerant
glutinous or not
yellow, white or black
length of time in stomach
fertilizer responsiveness
distinctive aroma
expansion when cooked
yields from 1.2 to 6.2t/haSource: Fujisaka et al, 1992