Table 1.

Various characteristics of the four typical Chinese rice-growing regions

	Hani Terrace	Taihu Plain	Sanjiang Plain	Lianghu Plain
Administrative region	Yunnan Province.	Jiangsu, Zhejiang, Anhui Provinces, and Shanghai Municipality	Heilongjiang Province	Hunan and Hubei Provinces
Longitude range	100°55′27″–103°14′57″	118°38′12″–121°47′48″	130°12′45″–134°8′45″	111°50′51″–114°48′12″
Latitude range	22°46′44″–24°28′13″	30°3′19″–31°56′15″	45°16′53″–48°2′40″	28°34′7″–31°16′21″
Climate	3-D climate, (sub)tropics	subtropics	temperate	subtropics
Elevation (m)	350–3000	0–45	50–160	10–100
Rice cultivation history	~ 1200 years	~ 5000 years	~ 60 years	~ 4000 years
Rice cultivars (Oryza sativa L.) [89]	Most are japonica	Half are indica and half are japonica	All are japonica	Most are indica
Cultivation method	traditional	modern and small-scale	modern and large-scale	modern and medium-scale
Mean pH	6.07 ± 0.60	6.60 ± 0.70	6.32 ± 0.32	6.80 ± 0.68
Mean annual temperature (°C)	16.21 ± 1.77	15.66 ± 0.41	2.85 ± 0.78	16.68 ± 0.35
Mean annual precipitation (mm/d)	3.20 ± 0.19	3.74 ± 0.19	1.86 ± 0.13	3.45 ± 0.29
Dissolved organic carbon (mg/ml)	23.51 ± 6.84	31.68 ± 11.41	29.28 ± 8.39	31.61 ± 14.40