Yield response of high-yielding rice cultivar Oonari to different environmental conditions

Figures & data

Table 1. Cultivation methods.

Location	Site			Year	Plot	Reprication	Sampled hill
					area (m^2)		no. per rep.
Tsukuba	Experimental paddy field at NARO Institute of Crop Science	Tsukubamirai, Ibaraki	36°02′ N, 140°04′ E	2013	5.4	6	48
				2017	17.9	4	48
Fukuyama	Experimental paddy field at the NARO Western Region Agricultural Research Center	Fukuyama, Hiroshima	34°29′ N, 133°23′ E	2013	11.5	3	60
				2014	7.2	3	42
Nagano	Experimental paddy field at the Nagano Agricultural Experiment Station	Suzaka, Nagano	36°39′ N, 138°17′ E	2017	4.8	2	40
FACE	Farmers’ fields	Tsukubamirai, Ibaraki	35°58′ N, 139°60′ E	2017	6.5	3	20

Planting density at 22.2 hills m⁻² (15 cm × 30 cm), with one plant per hill in Tsukuba and three plants per hill in the other sites.

Table 2. Grain yield and yield components of Oonari and Takanari in field experiments.

	Year	Cultivar	Whole brown rice yield (g m^−2)	Filled brown rice yield (g m^−2)	Panicle no. (m^−2)	Spikelet no. (panicle^−1)	Total spikelets (×103 m^−2)	Filled spikelets (%)	1000-grain wt. (g)
Tsukuba	2013	Oonari	1053	1016	321	208	66.6	72.2	21.1
		Takanari	1068	1042	289	220	63.3	79.0	20.8
	2017	Oonari	983	951	315	177	55.8	78.4	21.8
		Takanari	905	884	283	190	53.7	76.6	21.5
Fukuyama	2013	Oonari	1044	962	394	142	55.9	80.5	21.4
		Takanari	1049	990	371	148	54.8	84.6	21.4
	2014	Oonari	1003	908	368	170	62.6	66.1	22.0
		Takanari	1009	922	326	190	61.7	68.3	21.9
Nagano	2017	Oonari	1013	996	288	183	52.6	86.6	21.9
		Takanari	984	961	278	201	55.8	81.3	21.3

Grains thicker than 1.6 mm in Tsukuba and Nagano and 1.8 mm in Fukuyama were considered as filled brown rice and were counted to calculate 1000-grain weight. Yield and 1000-grain weight are presented at a water content of 15%. The percentage of filled spikelets was calculated as the number of filled spikelets divided by the total number of spikelets.

Table 3. Weather conditions during the growing periods of Oonari.

Site	Year	Transplanting date	Heading date	Harvest date	Mean air temperature		Cumulative solar radiation
					(°C day^−1)		(MJ m^−2)
					Before heading	40 days after heading	Before heading	40 days after heading
Tsukuba	2013	May 10	Aug 1	Sep 10	22.5	26.8	1488	719
	2017	May 18	Aug 4	Sep 27	23.6	24.6	1476	530
Fukuyama	2013	May 13	Jul 30	Sep 13	24.8	27.8	1535	723
	2014	May 13	Jul 31	Sep 13	23.6	26.1	1471	544
Nagano	2017	May 11	Aug 15	Sep 30	21.9	21.6	2027	663

Figure 1. Relationship between cumulative solar radiation during 40 days after heading and whole brown rice yield of Oonari. *p < 0.05.

Figure 2. Relationship between mean air temperature before heading and panicle number of Oonari. *p< 0.05.

Table 4. Grain yield and yield components of Oonari affected by CO₂ concentration in Tsukubamirai in 2017.

CO2 concentration	Whole brown rice yield (g m^−2)	Filled brown rice yield (g m^−2)	Panicle no. (m^−2)	Spikelet no. (panicle^−1)	Total spikelets (×10^3m^−2)	Filled spikelets (%)	1000-grain wt. (g)
Ambient (A)	803	776	325	158	51.2	67.9	22.3
FACE (F)	937	900	358	164	59.0	69.0	22.1
F/A	1.17	1.16	1.10	1.04	1.15	1.02	0.99
t-test results	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.	n.s.

n.s., not significant.