Genotypic Variability in Some Morpho-Physiological Traits in Different Environments and Their Relationship with Cassava (Manihot esculenta Crantz) Root Yield

Table 7

Estimates of variance components, heritability, and phenotypic and genotypic coefficients of variation for nine traits in 20 cassava genotypes across six environments.

Traits			σ^2e	σ^2p	H^2	GCV	PCV	PCV : GCV	GA	GAM
St_cond (mmol^−2s^−1)	186.61	127.67	1051.00	1365.28	13.67	7.58	20.49	2.70	19.23	10.67
Leaf temp (°C)	0.10	0.044	0.93	1.03	9.45	0.89	2.90	3.25	0.32	0.92
Plt_ht (cm)	878.29	84.37	775.70	1738.36	50.52	15.99	22.50	1.41	70.89	38.26
Levs_plt	2786.50	956.00	7377.00	11119.50	25.06	38.79	77.48	2.00	65.80	48.34
Branchno_plt	23.33	5.28	34.85	63.46	36.77	39.86	65.73	1.65	3.43	28.31
CMDSc	0.39	0.15	0.19	0.73	53.42	37.65	51.51	1.37	1.08	64.81
AGBio (t ha^−1)	18.62	10.76	41.18	70.56	26.39	25.30	49.24	1.95	5.78	33.88
Rt_yld (t ha^−1)	44.85	14.14	52.18	111.17	40.34	26.20	41.25	1.57	10.34	40.46
Rt_girth (cm)	0.70	0.08	1.32	2.09	33.39	14.56	25.19	1.73	1.25	21.83
Rt_length (cm)	20.54	2.49	31.61	54.64	37.59	11.17	18.21	1.63	3.35	8.26
Rtno_plt	0.95	0.34	2.80	4.09	23.31	13.87	28.74	2.07	1.03	14.57
Harvest index	0.0033	0.0004	0.0030	0.0067	49.04	9.9258	14.1736	1.4280	0.1140	19.7408
L : G ratio	2.02	0.19	1.73	3.94	51.27	18.49	25.83	1.40	1.44	18.70

 = genotypic variance,  = genotype x environment variance, σ²_e = environmental variance, σ²_p = phenotypic variance, H² = broad-sense heritability, PCV = phenotypic coefficient of variation, GCV = genotypic coefficient of variation, PCV : GCV = ratio of phenotypic to genotypic coefficients of variation, GA = genetic advance, GAM = genetic advance as percentage of the mean, St_cond = stomatal conductance (mmol⁻²s⁻¹), Leaf temp = leaf temperature (°C), Branchno_plt = number of branches per plant, Levs_plt = number of leaves per plant, Plt_ht (cm) = plant height (cm), CMDSc = cassava mosaic disease severity score (scale of 1–5 where 1 = no symptom and 5 = highly diseased plants), AGBio = above ground biomass yield (t ha⁻¹), HI = harvest index, Rt_yld = storage root yield (t ha⁻¹), Rtno_plt = root number per plant, Rt_girth = storage root girth (cm), Rt_length = storage root length (cm), and L : G ratio = root length : girth ratio.