Marker-assisted breeding of the rice restorer line Wanhui 6725 for disease resistance, submergence tolerance and aromatic fragrance

Rice

Table 4 Grain quality of MH725, WH6725 and hybrid rice^a

Trait	Inbred rice			Hybrid rice
Trait	MH725	WH6725	P-Value	II-32A/MH725	II32A/WH6725	P-Value
Grain length (mm)^b	6.8 ± 0.1 (Long)	7.0 ± 0.1 (Long)	0.04	6.4 ± 0.2 (Medium)	6.1 ± 0.3 (Medium)	0.13
Ratio of length to width^c	2.9 ± 0.2 (Medium)	3.0 ± 0.1 (Medium)	0.39	2.6 ± 0.2 (Medium)	2.5 ± 0.0 (Medium)	0.80
Degree of chalkiness (%)^d	4.7 ± 4.0 (1)	5.8 ± 5.4 (1)	0.23	13.5 ± 8.0 (5)	10.5 ± 3.0 (5)	0.56
Amylose content (%)^e	16.3 ± 1.3 (Low)	15.6 ± 1.2 (Low)	0.19	23.4 ± 0.4 (Intermediate)	23.8 ± 0.1 (Intermediate)	0.50
Gel consistency (mm)^f	76.2 ± 5.2 (Soft)	80.5 ± 7.6 (Soft)	0.21	69.5 ± 7.8 (Soft)	60.0 ± 17.0 (Soft)	0.68
Alkali spreading value and Gelatinization temperature^g	6.3 ± 0.3, GT <70 ^oC (Low)	6.4 ± 0.5, GT < 70 ^oC (Low)	0.50	5.8 ± 1.1, GT < 70 ^oC (Low)	6.2 ± 0.2, GT < 70 ^oC (Low)	0.63
Fragrance^h	Non-aromatic	Strongly aromatic	-	Non-aromatic	Non-aromatic

^aThe rice grain quality was evaluated for four times using the rice seeds harvested in 4 field trials as described in Table 2
^bCategory of grain length: Very long, grain length (GL) > 7.5 mm; Long, 6.6 mm < GL ≤ 7.5 mm; Medium, 5.5 mm < GL ≤ 6.6 mm; Short, GL ≤ 5.5 mm
^cRatio of length to width (L/W ratio): Slender, L/W ratio > 3.0; Medium, 2.0 < L/W ratio ≤ 3.0; Bold, L/W ratio, ≤ 2.0
^dScale for degree of chalkiness (DC): 0, DC = 0; 1, 0 < DC ≤ 10%; 5, 10% < DC ≤ 20%; 9, DC > 20%
^eClassification of amylose content (AC): Waxy, AC ≤ 2%; Very low, 2% < AC ≤10%; Low, 10% < AC ≤ 20%; Intermediate, 20% < AC ≤ 25%; High, AC > 25%
^fClassification of gel consistency (GC): Soft, GC > 60 mm; Medium, 40 mm < GC ≤ 60 mm; Hard, GC ≤ 40 mm
^gGrade of gelatinization temperature (GT) estimated by alkali spreading value (ASV): High, 74.5 °C ≤ GT < 80 °C, 1 ≤ ASV < 2.5; Intermediate high, 74 °C ≤ GT < 74.5 °C, 2.5 ≤ ASV < 3.5; Intermediate, 70 °C ≤ GT < 74 °C, 3.5 ≤ ASV < 5.5; Low, GT < 70 °C, 5.5 ≤ ASV ≤ 7
^hScale of fragrance was characterised as strongly aromatic, moderately aromatic, slightly aromatic and non-aromatic as described previously (Cruz and Khush 2000)