options ps=60 ls=80 pageno=1 formdlim='_';

data wheat;
input yield variety $ block $;
cards;
10 A I
 9 B I
11 C I
15 D I
10 E I
12 F I
11 G I
11 A II
10 B II
12 C II
12 D II
10 E II
11 F II
12 G II
12 A III
13 B III
10 C III
14 D III
15 E III
13 F III
13 G III
14 A IV
15 B IV
13 C IV
17 D IV
14 E IV
16 F IV
15 G IV
13 A V
14 B V
16 C V
19 D V
17 E V
15 F V
18 G V
;

proc glm;
class variety block;
model yield = variety block;
random block;
lsmeans variety/pdiff cl adjust=tukey;
run;

proc glm;
class variety block;
model yield = variety;
run;