Straighthead disease is a physiological disorder in rice and the most widespread non-fungal disease of the U.S. straighthead greatly reduces rice yield. Straighthead studies were most conducted in the artificial field which was Arsenic amendment plots due to the similarity of straighthead symptoms of Arsenic damage. To evaluate the straighthead disease resistance in natural condition, 46 rice lines, including 24 inbred lines and 22 hybrid combinations which were developed from breading program, were chosen for straighthead and agronomy characters testing in a native soil where straighthead naturally induced in the past years at University of Arkansas at Pine Bluff (UAPB), Arkansas in 2011 and 2012. The straighthead of rice were rated from 0 to 9 levels, and 0 was the least straighthead disorder and 9 was the most severe straighthead disorder. Cocodrie (CCDR) was used as the check in this study. The results of 2011 showed that the yields of 8 entries were higher than the check CCDR. The straighthead scores of these 8 entries were 0 - 1 which indicated their resistance to straighthead. The rest of the entries had lower yields than check CCDR with straighthead scores 5 - 6 which indicated their moderate susceptibility to straighthead. The yields were negatively related to the straighthead scores (r = - 0.9178, P < 0.01). The results of 2012 showed that the yields of 9 hybrids and 6 inbred entries were higher than the check CCDR. The straighthead scores of top 12 entries were 0 - 2 which indicated that they were resistant to straighthead and 3 entries with straighthead score of 3 which indicated they were moderately resistant to straighthead. The rest 3 hybrids and 4 inbred entries had lower yields than the check and their straighthead scores were 5 - 6 which indicated their moderately susceptible to straighthead. The yields was negatively related to the straighthead scores (r = -0.956, P < 0.01). Compared to CCDR, the yield of hybrids showed their straighthead resistance at some extent. The yields of top six entries, hybrid 33A/PB23, inbred 3053, hybrid 28s/PB22, 28s/PB24, 29s/PB24 and inbred 3222, were 10,376.4, 9991.4, 9566.7, 9334.3, 9183.9 and 9174.3 Kg/Ha, and 46.0%, 40.7%, 34.7%, 31.4%, 29.3%, and 29.5% higher than the check, respectively.
Straighthead disease is a physiological disorder in rice that results in sterile florets with distorted lemma and palea. The panicles or heads may not form at all in extreme cases (
This experiment was conducted at UAPB (University of Arkansas at Pine bluff, USA) farm (Latitude: 34˚15'N, Longitude: 92˚01'W, Elevation: 70.7 meters) in 2011 and 2012. Forty-six rice lines, including 32 (CCDR and Francis used for both years) inbred lines and 12 hybrid combinations were randomized block designed with 4 Replications. Each Entry was with 1 row × 1 m × 0.4 m, Sowing 15 seeds per row but keeping 10 plants per row. Cocodrie is known to be susceptible (S) to straighthead, so it has been widely used as a susceptible check in studies of straighthead; 150 kg/h2 of urea and 300 kg/h2 of N.P.K. (13-13-13) were applied 2 times, respectively. Insecticide was applied 3 times and no any fungicide was applied. Straighthead severity was recorded at physiological maturity by using a 0 - 9 rating scale: “0” rating indicating no signs of stress with >90% seed set and no parrot beaking or twisting of panicles, and “9” rating for plants that are stunted and do not extrude panicles described by Yan et al. [
0: 91% - 100% of grains developed and no apparent damage at all;
1: 81% - 90% of grains developed and no apparent damage;
2: 71% - 80% of grains developed and 96% - 100% of panicles completely emerged;
3: 61% - 70% of grains developed and 91% - 95% of panicles completely emerged;
4: 41% - 60% of grains developed and 86% - 90% of panicles completely emerged;
5: 21% - 40% of grains developed and 81% - 85% of panicles completely emerged, initial appearance of distorted and parrot-break grains;
6: 11% - 20% of grains developed and 76% - 80% of panicles completely emerged;
7: 0% - 10% grains developed and most panicles completely emerged but totally upright;
8: no grains developed and 0% - 10% of panicles emerged; and
9: no panicles emerged with stubby plants.
The samples for agronomy characters testing were harvested after straighthead scoring and the rest of data were collected at harvest for each plot of entry at the time of ripening. Data analyzed by using SAS 12.0 for the
standard error and correlation.
In year 2011, a total of 24 lines were tested and the results presented in
In year 2012, 12 hybrids and 12 inbred lines were tested and the results presented in
Straighthead reduced the yield for susceptible varieties. Most of the hybrid lines showed higher resistance to straighthead and had higher grain yields than conventional cultivars. Twelve inbred varieties, 9-718, 9-710, Rondo, PB-12, 9-186, PB-13, PB-2, PB-11, 3035, 3222, 2854, and 3137, showed highly resist to straighthead, and can be used in hybrid breeding. Four hybrids 33A/PB23, 28s/PB22, 28s/PB24, and 29s/PB24 can be further
Order | Name of line | Yield | STD Error | Over check | Seed set | Grain weight | Straighthead score |
---|---|---|---|---|---|---|---|
Kg/Ha | (%) | (%) | g/1000 seeds | ||||
1 | CCDR(check) | 5073.5 | 1376.2 | 0 | 76.4 | 19.6 | 5 |
2 | 9-718 | 8698.4 | 686.6 | 71.5 | 71.3 | 28.3 | 0 |
3 | 9-710 | 8098.6 | 692.6 | 59.6 | 77.4 | 26.8 | 0 |
4 | Rondo | 8071.7 | 675.0 | 59.1 | 80.2 | 22.1 | 0 |
5 | PB-12 | 6562.1 | 736.8 | 29.3 | 72.3 | 27.2 | 0 |
6 | 9-186 | 6471.8 | 653.0 | 27.6 | 72.1 | 23.3 | 0 |
7 | PB-13 | 6126.8 | 709.0 | 20.8 | 75.2 | 23.8 | 1 |
8 | PB-2 | 6034.0 | 80.0 | 18.9 | 61.9 | 24.3 | 1 |
9 | PB-11 | 5587.7 | 348.7 | 10.1 | 75.9 | 27.8 | 0 |
10 | PB-9 | 4657.7 | 588.9 | −8.2 | 71.8 | 20.8 | 5 |
11 | PB-6 | 4616.0 | 219.7 | −9.0 | 70.6 | 20.2 | 5 |
12 | 9-185 | 4577.9 | 1048.0 | −9.8 | 65.8 | 21.3 | 5 |
13 | 9-721 | 4567.8 | 330.3 | −10.0 | 66.6 | 24.4 | 5 |
14 | PB-18 | 4141.6 | 915.3 | −18,4 | 51.7 | 26.6 | 5 |
15 | 9-712 | 4075.6 | 1090.4 | −19.7 | 65.7 | 28 | 5 |
16 | Francis | 3923.0 | 468.1 | −22.7 | 72.8 | 17.9 | 5 |
17 | PB-5 | 3881.1 | 215.1 | −23.5 | 58.6 | 22.9 | 5 |
18 | Jansmine-85 | 3817.5 | 622.4 | −24.8 | 38 | 19.9 | 5 |
19 | PB-1 | 3748.6 | 683.2 | −26.1 | 70.8 | 20.7 | 5 |
20 | 9-184 | 3412.7 | 898.3 | −32.7 | 38.3 | 23.4 | 6 |
21 | 9-725 | 3272.2 | 92.9 | −35.5 | 53.4 | 26.4 | 6 |
22 | 9-720 | 2987.0 | 921.6 | −41.1 | 71.1 | 24.5 | 6 |
23 | 9-714 | 2747.0 | 140.4 | −45.9 | 57 | 25.1 | 6 |
24 | 9-726 | 2574.0 | 161.1 | −49.3 | 62.6 | 28.6 | 6 |
ID | Inbred or hybrid | Yield | STD Error | Over check | Height | Panicle | Seed set | Straighthead score |
---|---|---|---|---|---|---|---|---|
Kg/Ha | % | cm | No/Plant | % | ||||
1 | CCDR (check) | 7105.2 | 599.9 | 0 | 99.9 | 9.9 | 86.9 | 5 |
2 | 33A/PB23 | 10376.4 | 1049.4 | 46.0 | 115.7 | 14.4 | 82.8 | 0 |
3 | 3035 (8-2/Rondo) | 9991.4 | 458.6 | 40.6 | 101.3 | 12.6 | 83.6 | 0 |
4 | 28s/PB22 | 9566.7 | 80.3 | 34.6 | 118.9 | 15.9 | 84 | 0 |
5 | 28s/PB24 | 9334.3 | 123.5 | 31.4 | 117.4 | 14.1 | 84.9 | 0 |
6 | 29s/PB24 | 9183.9 | 321.5 | 29.3 | 116.7 | 14.3 | 85.7 | 0 |
7 | 3222 (Rondo/8-7) | 9174.3 | 1186.8 | 29.1 | 101.8 | 14.3 | 78.4 | 0 |
8 | 28s/PB23 | 8659.5 | 1177.6 | 21.9 | 120.6 | 16.8 | 86 | 1 |
9 | 2854 (8-12/Jasime-85) | 8542.6 | 837.0 | 20.2 | 102.7 | 15.3 | 84.9 | 1 |
10 | 30s/PB23 | 8494.4 | 262.5 | 19.6 | 115.9 | 13.8 | 85.6 | 1 |
11 | 3137 (Rondo/8-7) | 8421.2 | 826.3 | 18.5 | 98.3 | 15.4 | 84.7 | 2 |
12 | 2527 (8-16/Rondo) | 8256.5 | 948.1 | 16.2 | 99.7 | 14.2 | 88.8 | 1 |
13 | 33A/PB5 | 8098.0 | 1527.5 | 14.0 | 121.6 | 15.8 | 80.2 | 1 |
14 | 3168 (Rondo/8-7) | 7554.1 | 1193.0 | 6.3 | 96.8 | 12.8 | 78.2 | 3 |
15 | 28s/PB5 | 7143.0 | 1347.2 | 0.5 | 115.9 | 14.1 | 67.5 | 3 |
16 | 33A/PB5 | 6948.1 | 789.2 | −2.2 | 115.6 | 13 | 78.8 | 3 |
17 | Francis | 6931.9 | 474.2 | −2.4 | 102.6 | 8.7 | 87.2 | 5 |
18 | 33A/PB21 | 6859.2 | 1385.0 | −3.5 | 117.7 | 14.4 | 68.9 | 3 |
19 | 28s/PB21 | 6034.2 | 629.3 | −15.1 | 105.6 | 12 | 66.4 | 5 |
20 | 30s/PB21 | 6022.6 | 808.3 | −15.2 | 111 | 14.2 | 74.8 | 5 |
21 | 3468 (Francis/8-18) | 5608.2 | 399.3 | −17.1 | 98.6 | 7 | 88.9 | 6 |
22 | 3054 (Francis/8-13) | 5575.0 | 360.2 | −21.5 | 98.1 | 7.8 | 83.3 | 6 |
23 | 3084 (Francis/8-13) | 5197.4 | 728.0 | −26.9 | 103.1 | 11.3 | 88.9 | 6 |
24 | 3957 (Francis/8-13) | 5052.3 | 212.8 | −28.9 | 87.7 | 12 | 77.1 | 6 |
tested for the use in the rice production in future.
Bihu Huang,Zongbu Yan, (2016) Straighthead and Agronomy Characters Testing for Selected Parent Lines and Hybrid Combinations at UAPB in 2011-2012. American Journal of Plant Sciences,07,1423-1428. doi: 10.4236/ajps.2016.710136