Molecular Plant Breeding 2016, Vol.7, No.19, 1
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out other traits which contribute rest of the percentage of the yield.
Figure 1 Path diagram of different yield contributing characters on yield at genotypic level
Note: PH= Plant height, PB/P= No. of primary branches/plant, SB/P= No. of secondary branches/plant, DFFL= Days to first
flowering, D50%F= Days to 50% flowering, DFM = Days to fruit maturity, FD= Fruit diameter, FL= Fruit length, FW= Fruit weight,
F/P= Fruits/plant, 100SW= 100 seed weight, Y/P= Yield/plant
1.3 Selection index
Selection indices were constructed through discriminant function involving the yield/plant as an independent
variable index and four yield components which had positive correlation and positive direct effect on yield at
genotypic level. The expected genetic gain in yield and the relative efficiencies of different selection indices,
individually and in different combinations are shown in Table 3. The individual trait index, fruit weight had the
highest relative efficiency (114.69%) indicated the importance of this trait as yield attribute. This finding was
further confirmed by the fact that whenever fruit weight was added to or it replaced other traits in a selection index,
the efficiency of such index was tremendously improved. The minimum genetic gain 0.55 and 0.58 and the
minimum relative efficiencies 48.51% and 50.91% were obtained by the indices having single traits, viz., primary
branches/plant and fruit length, respectively. Furthermore, when primary branches/plant was added to or it replaced
another character in a selection index, the relative efficiency of such an index was drastically reduced. Therefore, it
could be concluded that primary branches/plant is an inefficient selection criterion for the improvement of yield.
In this study, the expected genetic gain and the relative efficiency of the index was increased with the increase in the
number of characters involved except in few cases. The selection index involving all the five characters exhibited
the highest expected genetic gain (2.7) and the maximum relative efficiency (236.47%).
Among two character combinations, the maximum efficiency was obtained (183.91%) based on fruit weight+
yield/plant. When three characters were included in the selection index, maximum relative efficiency over
selection for yield was obtained (215.51%) for the index based on fruit weight+ fruits/plant+ yield/plant. Another
combinations as fruit length +fruit weight +yield/plant had also showed higher relative efficiency.
Considering four characters, maximum relative efficiency was obtained (235.04%) in combination of fruit length
+fruit weight+ fruits/plant+ yield/plant. The other combination as primary branches/plant + fruit length +fruit
weight+ yield/plant had also higher efficiency over selection for grain yield/plant.
