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

Table 6

Combined analysis of variance for physiological parameters, growth parameters, root yield, and yield components of 20 cassava genotypes in six environments.

Traits	Sources of variation (degrees of freedom)
	Environment (E) (df = 5)^¥	Rep (Env) (df = 12)	Genotype (G) (df = 19)	G × E (df = 95)	Error (df = 228)
St_cond (mmol^−2s^−1)	284443.82	10666.25	2334.88	1725.02	1051.04
Leaf temp (°C)	93.84	11.41	1.46ns	0.85ns	0.93
Plt_ht (cm)	209255.70	2479.1	15303.00	1281.90	775.7
Levs_plt	388753.78	9711.18	44420.61	13113.46	7377.27
Branchno_plt	1984.39	77.69	388.37	66.50	34.84
CMDSc (1–5)	14.55	0.58	6.13	1.08	0.19
AGB (t ha^−1)	2999.32	87.96	270.17	104.54	41.18
Harvest index	0.436	0.014	0.06	0.02	0.003
Rt_yld (t ha^−1)	3114.57	95.86	715.89	136.35	52.18
Rtno_plt	39.08	5.47	15.15	4.83	2.76
Rt_girth (cm)	92.41	2.09	12.11	1.78	1.314
Rt_length (cm)	2051.68	40.16	348.85	46.07	31.61
L : G ratio	333.84	8.19	34.96	2.95	1.84

Significant at ; significant at ; significant at ; ns = not significant (). ^¥Values in parenthesis represent the degrees of freedom for the various sources of variation. St_cond = stomatal conductance (mmol⁻²s⁻¹), Leaf temp = leaf temperature (°C), Plt_ht (cm) = plant height (cm), Levs_plt = number of leaves per plant, Branchno_plt = number of branches per plant, CMDSc = cassava mosaic disease severity score (scale of 1–5 where 1 = no symptom and 5 = highly diseased plants), AGB = above ground biomass yield (t ha⁻¹), HI = harvest index, Rt_yld (t ha⁻¹) = storage root yield (t ha⁻¹), Rtno_plt = storage rood number per plant, Rt_girth = storage root girth (cm), Rt_length = storage root length (cm), and L : G ratio = storage root length : girth ratio.