# Environment- and Genotype-Dependent Irrigation Effect on Soybean Grain Yield and Grain Quality
## 3 Results
### Grain Protein Content and Crude Protein Yield  
All of the interactions (AB, AC, BC and ABC) were highly significant (\(p<0.01\)) sources of variation for soybean grain protein content (Table 3) and crude protein yield (Table 4). The irrigation had a positive effect on the grain protein content and crude protein yield, but it varied across the growing seasons and genotypes. In the A1 growing season, A1B2 resulted in a 1.8% protein content increase, while A1B3 resulted in a 0.97% increase compared to A1B1 (Table 3). On the other hand, there were no significant differences in the crude protein yields between the different irrigation treatments (B) in A1 (Table 4). In the A2 growing season, A2B2 resulted in a 5% grain protein content increase, while A2B3 resulted in a 7% increase compared to A2B1. The crude protein content was 9.3% higher in A2B2 and 5.3% higher in A2B3 compared to A2B1 (Table 4). In the A3 growing season, the irrigation had a negative effect. A3B3 resulted in an almost 2% grain protein content decrease compared to A3B1, while A3B3 resulted in a 3.7% decrease (Table 3). Nevertheless, the crude protein yield increased by 25.22% in A3B2 and by 38.98% in A3B3 compared to A3B1 (Table 4). The grain protein contents in A4B1 and A4B2 were almost the same, but A4B3 had a 1.4% increase compared to A4B1 (Table 3); however, the crude protein yield was 34.97% higher in A4B2 and 43.17% higher in A4B3 compared to A4B1 (Table 4). B3 was significantly higher compared to B2 for crude protein content in the A2, A3 and A4 growing seasons (Table 4).  
The variability between the genotypes was smaller for the mean protein content than for the mean grain yield. The environmental conditions in the A1 growing season resulted in the highest grain protein content for all of the genotypes (C1-C4), followed by A2, A4 and, finally, A3 (Table 3). The irrigation effect also varied among the genotypes. The most noticeable irrigation effect on the grain protein content was determined for C1, but the irrigation effect was almost non-existent for C3 and C4 (Table 3). On the other hand, the crude protein yield significantly varied depending on the irrigation treatment (B) for all of the genotypes (Table 4). Genotype C1 had the highest increase, with a 27.83% higher crude protein yield in B2 and a 39.68% higher crude protein yield in B3 compared to B1. C2 had a 23.21% higher crude protein yield in B2 and a 20.42% higher crude protein yield in B3 compared to B1. The crude protein yield was 7.35% higher in B2C3 and 10.09% higher in B3C3 compared to B1C3. Similarly, the crude protein yield was 8.44% higher in B2C4 and 10.88% higher in B3C4 compared to B1C4. B3 was significantly higher compared to B2 for crude oil content only for the C1 genotype (Table 4).  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{
\begin{tabular}{c} **Growing** \\ **Season (A)** \\ \end{tabular} } & \multicolumn{6}{c}{**Grain Yield (kg ha\({}^{-1}\))**} \\ \cline{2-9}  & \multicolumn{3}{c}{**Irrigation (B)**} & \multirow{2}{*}{**Mean A**} & \multicolumn{3}{c}{**Soybean Genotype (C)**} \\ \cline{2-9}  & **B1** & **B2** & **B3** & & **C1** & **C2** & **C3** & **C4** \\ \hline A1 & 3460 & 3420 & 3448 & 3443 & 3518 & 3410 & 3475 & 3367 \\ A2 & 4034 & 4217 & 3953 & 4068 & 3431 & 4357 & 4242 & 4243 \\ A3 & 2997 & 3834 & 4328 & 3720 & 3480 & 3818 & 3788 & 3791 \\ A4 & 3000 & 4050 & 4235 & 3762 & 3587 & 3581 & 3942 & 3936 \\ \hline Mean B & 3373 & 3880 & 3991 & Mean C & 3504 & 3791 & 3862 & 3834 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Impacts of the environmental conditions in the four growing seasons (A1–A4), three treatments (B1, rain-fed conditions; B2, 60% of the field water capacity, or FWC; B3, 80–100% of the FWC), four, genotypes (C1–C4) and their interactions (AB, AC, BC and ABC) on soybean grain yield (kg ha\({}^{-1}\)).