add estimation of heritability protocol

assays/StatisticalAnalysis/protocols/EstimationOfHeritability.md

+## Estimation of heritability
+
+Broad-sense heritability $(⁠H^2)$ was estimated for both field and climate chamber experiments based on the following method:
+
+**(8)**
+$$H^2 = \frac{\sigma_G^2}{\sigma_G^2 + \frac{\bar{\upsilon}_\delta^BLUE}{2}}$$
+where $\sigma_G^2$ was the genotypic variance calculated based on the above models with a random effect for $G_i$ and $\bar{\upsilon}_\delta^BLUE$ was the mean variance of the difference of two genotypic means (Holland et al., 2003; Piepho and Möhring, 2007).
+
+To avoid the effect of the varying number of replicates, the $H^2$ of photosynthesis-related parameters was estimated for each developmental stage based on the following equation:
+ 
+**(9)**
+$$H^2 = \frac{\sigma_G^2}{\sigma_G^2 + \frac{\sigma_{G:E}^2}{5} + \frac{\sigma_e^2}{5}}
+where $\sigma_{G:E}^2$ was the variance of the interaction of barley inbreds and environments, and $\sigma_e^2$ was the residual variance.
+
+We used the statistical software R to perform all statistical analyses.
\ No newline at end of file