\begin{table}[h]
\begin{tabular}{|ll|ll|l|l|ll|}
\hline
\multicolumn{2}{|l|}{\multirow{2}{*}{\begin{tabular}[c]{@{}l@{}}Plants whose growth\\ are to be compared \\ under the influence \\ of unpolarized and \\ polarized light\end{tabular}}} & \multicolumn{2}{l|}{\begin{tabular}[c]{@{}l@{}}Test statistic\\ calculated\\ (t value)\end{tabular}} & \multirow{2}{*}{\begin{tabular}[c]{@{}l@{}}T critical \\ at a 5\% \\ significance \\ level\end{tabular}} & \multirow{2}{*}{\begin{tabular}[c]{@{}l@{}}Degrees of \\ freedom\end{tabular}} & \multicolumn{2}{l|}{\begin{tabular}[c]{@{}l@{}}Result of t test\\ at 5\% significance\\ level(null hypothesis\\ rejected/accepted)\end{tabular}} \\ \cline{3-4} \cline{7-8} 
\multicolumn{2}{|l|}{}                                                                                                                                                                  & \multicolumn{1}{l|}{Height}                                  & Mass                                  &                                                                                                          &                                                                                & \multicolumn{1}{l|}{Height}                                                       & Mass                                                         \\ \hline
\multicolumn{2}{|l|}{\textit{P. vulgaris}}                                                                                                                                                       & \multicolumn{1}{l|}{3.901}                                   & 3.05                                  & \(\pm\) 2.15                                                                                  & 14                                                                             & \multicolumn{1}{l|}{Rejected}                                                     & Rejected                                                     \\ \hline
\multicolumn{2}{|l|}{\textit{V. radiata}}                                                                                                                                                        & \multicolumn{1}{l|}{-3.841}                                  & 4.85                                  & \(\pm\) 2.15                                                                                  & 14                                                                             & \multicolumn{1}{l|}{Rejected}                                                     & Rejected                                                     \\ \hline
\end{tabular}
\end{table}