North Carolina II ANOVA for combined and individual sets of parents for eight traits

4.3 Results

4.3.1 North Carolina II ANOVA for combined and individual sets of parents for eight traits

Standard errors for SCA effects were calculated as:

SE_SCA =√ [ ]

The relative importance of additive (GCA) and non-additive (SCA) genetic effects in determining the performance of the progeny for each of the traits was determined by individually expressing the GCA_f SS, GCA_m SS, and the SCA SS as a percentage of the treatment (crosses) SS.

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From the combined sets analysis, the GCA_f/Set and GCA_m/Set SS accounted for over 60%

of the treatment SS for all of the traits evaluated except DM% (Table 4.4). The GCA/Set SS of HI, UMNR, TRY and TRN had the highest contribution to the treatment SS of 85.0, 72.8, 72.4 and 68.0%, respectively. The SCA/Set contributed between 15.0 to 53.0% of the treatment SS, the highest contribution of 53.0% being recorded for DM%.

The GCA_f and GCA_m SS for Set 1 contributed over 50% of the treatment SS for the traits except DM% and HI (Table 4.5). The SCA SS contributed between 25.3 and 56.3% of the treatment SS, the highest contribution being 56.3% recorded for HI. In contrast to Set 1, the GCA_f and GCA_m SS for Set 2 contributed less than the SCA for AUDPC (46%) and DM%

(49.7%) (Table 4.6). At 77.8% of the treatment SS, the GCAf and GCAm SS for HI predominated over the SCA SS in contrast to Set 1. For the rest of the traits, GCA_f and GCAm SS in Set 2 accounted for higher proportions of the treatment SS than the SCA SS that is 60.9, 81.5, 83.8, 50.6 and 82.1% for SPVD, MRN, UMRN, TRN and TRY, respectively.

Table 4.4 North Carolina II ANOVA mean squares and sum of squares for both sets of parents for eight traits evaluated at Namulonge and Kachwekano (2011A)

NS = not significant; * = Significant at P≤0.05; ** = significant at P≤0.01; AUDPC = area under disease progress curve for Alternaria blight; SPVD = sweetpotato virus disease (score 1-9: 1 = no SPVD, and 9 = SPVD causing stunted growth); MRN = number of marketable storage roots per plant; UMRN

= number of unmarketable storage roots per plant; TRN = total number of storage roots per plant; TRY = total storage root fresh mass (t ha^-1); DM% = percentage dry mass composition; HI = harvest index; Site = Namulonge and Kachwekano; GCAf = female parent general combining ability; GCAm = male parent general combining ability; SCA = specific combing ability; %SS due to GCA and SCA expressed relative to the treatment SS

Source of variation

DF AUDPC SPVD MRN UMRN TRN TRY DM% HI

Site 1 135399.6** 65.36** 5.87* 8.2 ** 80.9** 6908.4** 117.3** 0.34**

Set 1 14316.7** 3.14** 0.17^NS 1.34** 5.8** 133.72^NS 47.7* 0.91^NS

Rep/Site*Set 4 8031.4** 1.97** 0.10^NS 0.89** 1.9* 123.6^NS 35.3** 0.01^NS

GCA_f/Set 5 13671.2** 4.91** 0.14* 0.98** 8.0* 211.8* 3.1^NS 0.04**

GCA_m/Set 7 11679.9** 0.34^NS 0.11* 0.27^NS 6.8^NS 104.2^NS 10.1^NS 0.02*

SCA/Set 18 4039.1** 0.82** 0.05^NS 0.14^NS 7.0^NS 37.8^NS 5.4^NS 0.01^NS

Site*Set 1 6922.5** 0.64^NS 0.09^NS 0.62* 3.5* 276.1* 5.7^NS 0.001^NS

Site*GCAf/Set 5 4313.1** 1.26** 0.11^NS 0.37* 1.0^NS 44.3^NS 1.3^NS 0.01^NS Site*GCA_m/Set 7 3552.9** 1.60^NS 0.03^NS 0.20^NS 0.5^NS 40.0^NS 11.5* 0.05^NS

Site*SCA/Set 18 1122.8** 0.33^NS 0.02^NS 0.17^NS 0.3^NS 39.9^NS 5.2^NS 0.01^NS

Error 60 24.2 24.20 0.22 0.37 0.7 8.2 2.3 0.08

Treatment SS 222820.1 41.6 2.30 9.40 21.9 2469.1 183.1 0.47

%SS due to GCA 67.4 64.6 64.3 72.8 68.0 72.4 47.0 85.0

%SS due to SCA 32.6 35.4 35.7 27.2 32.0 27.6 53.0 15.0

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Table 4.5 North Carolina II ANOVA means squares and sum of squares for Set 1 parents for eight traits evaluated at Namulonge and Kachwekano (2011A)

Source DF AUDPC SPVD MRN UMRN TRN TRY DM% HI

Site 1 54033.21*** 34.95*** 4.81*** 8.62*** 76.44** 6442.08* 113.07*** 0.26***

Rep(Site) 2 9333.53*** 1.54** 0.18^NS 1.34*** 3.02** 191.34^NS 13.56^NS 0.01^NS

GCAf 3 22084.00*** 5.23*** 0.03^NS 1.11*** 1.90* 65.19^NS 2.28^NS 0.02*

GCA_m 4 16814.72*** 0.40^NS 0.18* 0.36^NS 1.52^NS 149.43^NS 8.45^NS 0.01^NS

SCA 12 4434.22*** 0.71** 0.06^NS 0.18^NS 0.33^NS 38.65^NS 4.26^NS 0.01*

Site*GCA_f 3 6717.50*** 0.57^NS 0.07^NS 0.52* 1.64^NS 20.90^NS 1.58^NS 0.01*

Site*GCA_m 4 3880.14*** 0.60^NS 0.02^NS 0.29^NS 0.73^NS 60.99^NS 13.19^NS 0.01^NS

Site*SCA 12 1135.04^NS 0.29^NS 0.02^NS 0.17^NS 0.32^NS 21.91^NS 3.84^NS 0.01**

Error 38 620.70 0.26 0.06 0.16 0.63 73.25 5.45 0.01

Treatment SS 186721.50 25.83 1.50 6.93 1.81 1257.05 9.75 0.19

%SS due to GCA 71.5 66.9 55.2 68.9 74.7 63.1 44.3 43.7

%SS due to SCA 28.5 33.1 44.8 31.1 25.3 36.9 55.7 56.3

NS = not significant; * = Significant at P≤0.05; ** = significant at P≤0.01; AUDPC = area under disease progress curve for Alternaria blight; SPVD = sweetpotato virus disease (score 1-9: 1 = no SPVD, and 9 = SPVD causing stunted growth); MRN = number of market storage roots per plant; UMRN = number of unmarketable storage roots per plant; TRN = total number of storage roots per plant; TRY = total storage root fresh mass (t ha^-1); DM% = percentage dry mass composition; HI = harvest index; Site = Namulonge and Kachwekano; GCAf = female parent general combining ability; GCAm = male parent general combining ability; SCA = specific combing ability; %SS due to GCA and SCA expressed relative to the treatment SS

Table 4.6 North Carolina II ANOVA means squares and sum of squares for Set 2 parents for eight traits evaluated at Namulonge and Kachwekano (2011A)

Source DF AUDPC SPVD MRN UMRN TRN TRY DM% HI

Site 1 81394.74*** 31.28*** 1.75*** 1.63*** 19.38*** 1693.49*** 27.21* 0.11***

Rep(Site) 2 6729.30*** 2.41** 0.02^NS 0.45* 0.72^NS 55.86^NS 57.09*** 0.01^NS

GCA_f 2 1051.97^NS 4.43** 0.30** 0.80** 1.17* 431.75** 4.25^NS 0.06**

GCAm 3 4833.42*** 0.25*** 0.01^NS 0.15^NS 0.25^NS 43.80^NS 12.30^NS 0.03*

SCA 6 3249.06*** 1.03^NS 0.02^NS 0.07^NS 0.50^NS 36.19^NS 7.65^NS 0.01^NS

Site*GCA_f 2 706.52^NS 2.29** 0.17** 0.15^NS 0.15^NS 79.42^NS 0.83^NS 0.00^NS

Site*GCA_m 3 3116.49** 0.28^NS 0.00^NS 0.09^NS 0.19^NS 11.96^NS 9.20^NS 0.00^NS

Site*SCA 6 1098.43^NS 0.40^NS 0.03^NS 0.15^NS 0.31^NS 75.88^NS 7.96^NS 0.01^NS

Error 22 529.68 0.33 0.03 0.09 0.30 56.65 4.87 0.01

Treatment SS 36098.55 15.78 0.80 2.43 6.07 1212.01 91.31 0.28

%SS due to GCA 46.0 60.9 81.5 83.8 50.6 82.1 49.7 77.8

%SS due to SCA 54.0 39.1 18.5 16.2 49.4 17.9 50.3 22.2

NS = not significant; * = Significant at P≤0.05; ** = significant at P≤0.01; AUDPC = area under disease progress curve for Alternaria blight; SPVD = sweetpotato virus disease (score 1-9: 1 = no SPVD and 9 = SPVD causing stunted growth); MRN = number of marketable storage roots per plant; UMRN = number of unmarketable storage roots per plant; TRN = total number of storage roots per plant; TRY = total storage root fresh mass (t ha^-1); DM% = percentage dry mass composition; HI = harvest index; Site = Namulonge and Kachwekano; GCAf = female parent general combining ability; GCAm = male parent combining ability; SCA = specific combing ability. %SS due to GCA and SCA expressed relative to the treatment SS

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