Table 6. Summary of mean squares and significant tests of combining ability effects for tuber yield and growth traits under water stressed conditions for potato families evaluated at Adet, Ethiopia.

Source of variation	d.f	TTY	MTY	ATW	GC	PHT	CC
Set	1	0.0125*	0.018**	187.80***	144.43*	695.40***	6.13*
Replication (set)	2	0.0003ns	0.002ns	104.18***	64.95ns	173.14***	13.10**
GCAf	6	0.0160***	0.014***	77.56***	128.44***	158.50***	20.32***
GCAm	6	0.0147***	0.022***	235.51***	135.45***	171.05***	30.89***
SCA	18	0.0079***	0.008***	74.39***	88.16***	32.63***	5.32***
Error	30	0.0017	0.001	3.06	23.95	8.29	0.92
GCA/(GCA+SCA)%		65.992	68.39	67.79	59.95	83.47	82.81
Contribution of GCAf		34.340	26.43	16.79	29.18	40.15	32.86
Contribution of GCAm		31.652	41.95	50.99	30.77	43.32	49.95

d.f., degrees of freedom; TTY, total tuber yield (kg plant^-1); MTY, marketable tuber yield (kg plant^-1); ATW, average tuber weight (g); GC, groundcover (%); PHT, plant height (cm); CC, chlorophyll content (SPAD reading); GCA, general combining ability; GCA_f, general combining ability for female, GCA_m, general combining ability for male; SCA, specific combining ability.

*** p < 0.001

** p < 0.01

* p < 0.05

non-significant at p value 0.05.