Table 4.

Summary of hierarchical cluster analyses^a based on rice grain yields (at 14% grain moisture content), measured in the S. asiatica-infested field in Kyela, Tanzania (2011, 2012-1 and 2012-2) and the S. hermonthica-infested field in Mbita, Kenya (2010 and 2011); cluster 1 groups together the highest yielding cultivars of a particular screening trial, cluster 2 groups cultivars with intermediate high yields, cluster 3 represents cultivars of intermediate low yields and clusters 4 and 5 groups low yielding cultivars. Underlined are names of cultivars showing consistent good yields under Striga sp. infestation. For each cluster, the mean extrapolated rice grain yield (in t ha⁻¹) is shown.

Cluster	S. asiatica			S. hermonthica
	2011	2012-1	2012-2	2010	2011
High yielding
1	Supa India, CG14	N17b, CG14, WAB181-18	CG14	WAB56-50	WAB181-18
Mean	1.8	2.5	2.7	2.1	1.9
Intermediate-high yielding
2	N5, N12, N3, N4, N7, N9, N13, N14, N15, N17, WAB56-104, WAB56-50, WAB181-18	N3, N4, N14, N1, N5, N10, N12, N13, N2, N6, N7, N15, N16, N18, WAB56-50, WAB56-104, IAC165, Supa India	N1, N9, N10, WAB181-18, N2, N4, N5, N8, N13, N14, N17, N3, N6, N7, N11, N12, N15, N16, N18, WAB56-50, WAB56-104, Supa India, IAC165	N1, N2, N3, N9, N10, N11, N12, N14, WAB56-104	N3, N4, N8, N12, N13
Mean	1.0	1.9	1.5	1.4	1.5
Intermediate-low yielding
3	N2, N10, N11, N16, N18, IAC165, N1, N6, N8, Mwangulu	N8, N9, N11, Mwangulu	Mwangulu	N4, N5, N6, N7, N8, N15, N16- N17, N13, N18, WAB181-18, IAC165, CG14, IR49255-B-B-5-2	N1, N2, N5, N10, N11, N15, N16, N17, N18, IAC165, IR49255-B-B-5-2
Mean	0.6	1.2	1.0	0.7	1.2
Low yielding
4					N9, N14, WAB56-104
Mean					0.9
5					N6, N7, WAB56-50, CG14
Mean					0.6

^aThe Connectivity (Handl et al., 2005), Dunn Index (Dunn, 1974), and Silhouette Width (Rousseeuw, 1987) measures are used to optimize the number of clusters (see Section 2.6).

^bNERICA cultivars are abbreviated by ‘N’ following the specific number.