Dry matter accumulation and plant type of the high yielding soybean grown under converted rice paddy fields.

A high seed yield and associated attributes of dry matter production achieved by recent Japanese soybean cultivars

“…In fact, very high soybean yields that approach or exceed this estimated potential yield have been reported: 795 g m −2 (Van Roekel & Purcell, 2014) and 920 g m −2 (Isoda et al, 2006). The maximum soybean yields in the current study (590 and 658 g m −2 in Hatsusayaka and Sachiyutaka, respectively; Table 2) were 18 and 26% lower than that estimated potential yield but were equivalent to or higher than the previously reported high yields in Japan, which ranged from 528 to 649 g m −2 (Nakaseko et al, 1984;Shimada et al, 1990;Spaeth et al, 1987).…”

“…Many cloudy and rainy days occurred throughout the growth period in both years, and the temperature and daily total solar radiation from mid-August to mid-September (about R1 to R5) were lower than the 13-year mean. In 2014, western Japan received record-high precipitation, accompanied by low temperatures and short hours of sunshine from the summer to early may also contribute to the potential soybean yield in a converted paddy (Nakaseko et al, 1984). Hence, the reasons for the high yield in the current study should be explored from the vegetative stage to the R6 stage despite the relatively low solar radiation during this period (Fig.…”

“…This is because most of the soybean in Japan is cultivated in converted paddy fields, in which excess soil moisture frequently inhibits plant growth (Matsuo et al, 2013;Shimada et al, 2012). However, because the abovementioned high soybean yields in Japan (Nakaseko et al, 1984;Shimada et al, 1990;Spaeth et al, 1987) were obtained in converted paddy fields, the field itself is not a limiting factor for yield if soil moisture conditions are adequate. High soil fertility…”

“…On the other hand, CGR after R3 was significantly in terms of climate conditions and dry matter production as a function of light interception and RUE. Nakaseko et al (1984) estimated that an LAI of 8.4 is necessary to achieve 1200 kg m −2 of aboveground biomass in soybean based on a linear regression equation for the relationship between AGDM and maximum LAI derived from high-yield experiments. Another high-yield experiment in Japan showed that LAI must be greater than 7.2 to achieve a yield higher than 500 kg m −2 (Shimada et al, 1990).…”

“…) could be obtained in a converted paddy field (Nakaseko et al, 1984;Shimada et al, 1990;Spaeth et al, 1987). These results suggested that soybean's yield potential in Japan, which represents the yield in the absence of limitations caused by water and nutrient availability, diseases, and weeds, (Evans & Fischer, 1999), is potentially high if these and other constraints can be removed.…”