JIA-2019-11

2495 NIE Jun-jun et al. Journal of Integrative Agriculture 2019, 18(11): 2492–2504 elongation) was assessed by the Supervision, Inspection, and Test Center of Cotton Quality, Ministry of Agriculture and Rural Affairs (formerly Ministry of Agriculture) inAnyang, Henan Province of China, using a high volume instrument. 2.4. Statistical analysis The means and standard errors were calculated for three replicates from each treatment with Microsoft Excel 2010. The variance analysis was performed using the General Linear Models procedure of SPSS 20 (IBM, USA). Least signi cant differences (LSD) were used to separate treatment means at the 5% level. In the five-year data analysis, variety and year were entered as xed effects, while block (replicate) was entered as a random factor, the factor block was nested within year (Mao et al . 2015). All graphs were drawn using Sigma Plot 12.5 Software. 3. Results 3.1. Agronomic traits Plant height, first fruit branch node and height, the number of fruit branches and nodes, and the ratio of fruit nodes and branches were significantly affected by year, indicating that the agronomic traits were influenced by climate factors, e.g., rainfall and temperature (Table 1). Only the number of fruit branches was dramatically different, while the other characteristics did not display obvious differences among various cotton cultivars. The interaction between year and variety had a significant effect on the plant height and first fruit branch node and height. The coefficient of variation (CV) indicates the changes in agronomic traits in response to different climate conditions, such as temperature and rainfall over the five-year period. A lower CV indicates a lower effect of the climate and a more stable trait. The agronomic traits of the three varieties were inconsistent, but with respect to plant height, L21 was the most stable followed by J169 and 99B. The results of a comparison of plant height and first fruit branch node and height among the three varieties were not consistent from 2013 to 2017: J169 was the tallest, followed by 99B and L21; the first branch node of 99B was measured at the highest position, followed by J169 and L21; and the first branch height of L21 was the highest, followed by 99B and J169. No significant difference was observed in the number of fruit branches among the three varieties during the five-year experiment. The fruit node number of 99B was markedly higher than that of J169 and L21 in 2013, 2014, 2016, and 2017, while there were no obvious differences between J169 and L21 in those years. The ratio of fruit nodes and branches in L21 was Table 1 Agronomic traits of different boll-weight Bacillus thuringensis (Bt) cotton varieties in 2013–2017 Year 1) Variety 2) Plant height (cm) First fruit branch nodes per plant First fruit branch height (cm) Fruit branch no. per plant Fruit node no. per plant Ratio of fruit nodes and branches 2013 J169 124.73±1.19 a 6.83±0.15 a 22.33±0.06 c 13.73±0.57 a 74.93±1.19 b 5.46±0.15 b L21 107.70±0.72 c 6.27±0.12 b 28.07±0.55 a 13.85±0.15 a 78.61±0.25 b 5.68±0.06 b 99B 114.24±0.93 b 6.93±0.06 a 25.20±0.56 b 13.47±0.47 a 83.43±0.31 a 6.19±0.22 a 2014 J169 92.24±0.82 a 6.91±0.08 ab 18.08±0.02 b 13.83±0.23 a 54.77±1.16 b 3.96±0.06 b L21 88.27±0.54 a 6.70±0.26 b 22.42±0.43 a 13.91±0.37 a 57.41±0.93 b 4.13±0.06 b 99B 91.18±0.64 a 7.20±0.10 a 21.57±0.80 a 13.61±0.23 a 63.02±1.67 a 4.63±0.10 a 2015 J169 103.38±0.87 a 5.67±0.06 a 18.33±0.30 c 14.59±0.30 a 79.58±0.73 a 5.46±0.06 b L21 97.39±0.52 b 5.33±0.06 b 22.54±0.03 a 14.56±0.38 a 82.89±0.88 a 5.69±0.19 ab 99B 101.33±1.01 ab 5.83±0.06 a 19.51±0.32 b 14.02±0.32 a 83.01±0.85 a 5.92±0.17 a 2016 J169 118.11±0.81 a 5.44±0.12 a 21.49±0.34 b 13.15±0.33 a 58.51±0.77 b 4.29±0.08 c L21 108.61±2.50 b 4.53±0.06 b 25.88±0.88 a 12.59±0.08 a 60.14±0.82 b 4.78±0.03 b 99B 108.94±0.60 b 5.47±0.06 a 22.17±0.61 b 12.99±0.10 a 65.90±0.61 a 5.07±0.05 a 2017 J169 94.12±2.86 a 5.34±0.12 a 19.79±0.38 c 12.95±0.28 a 74.43±0.46 b 5.75±0.15 b L21 92.75±2.10 a 4.43±0.06 b 24.42±0.99 a 12.54±0.31 a 73.68±1.05 b 5.88±0.22 ab 99B 93.18±1.79 a 5.37±0.06 a 22.14±0.37 b 13.08±0.26 a 80.25±1.61 a 6.13±0.04 a CV (%) J169 13.55 a 12.81 c 9.42 a 4.70 b 16.13 a 15.32 a L21 9.11 c 18.60 a 9.65 a 6.57 a 15.98 a 14.30 b 99B 9.74 b 13.81 b 9.21 a 3.08 c 13.13 b 12.49 c P -value Y 0 0 0 0 0 0 V 0 0 0 0.2877 0 0 Y×V 0.0265 0.0036 0.0268 0.2513 0.1192 0.5487 1) CV, coefficient of variation. 2) J169, Jimian 169; L21, Lumianyan 21; 99B, Daizimian 99B. Y and V mean year and variety, respectively. Values are mean±standard deviation. Values followed by a different small letter within same row are significantly different in a column at 0.05 probability level.