The interaction of stem strength with plant density and nitrogen application in wheat progeny from parents with varying stem strength

Figures & data

Table I. Parental wheat cultivars used in this study, with their stem type and plant height data.

	Cultivar	Stem type	Plant height
1	SST 55	Normal stem	Tall semi dwarf
2	SST 806	Solid stem	Semi dwarf
3	DH 24	Solid stem	Short semi dwarf
4	DH 29	Solid stem	Short semi dwarf
5	BX	Normal stem	Tall semi dwarf

Table II. Analysis of variance for stem strength for internodes two, three and four for four different treatments for parents and F₁ hybrids.

Source of variance			Mean squares
Internode	Treatment	Entry	Replication	Error
2	1 (D1/F1)	59.01	163.60*	30.72
2	2 (D1/F2)	24.22	18.96	14.41
2	3 (D2/F1)	10.24	6.87	8.08
2	4 (D2/F2)	11.86**	2.55	4.13
3	1 (D1/F1)	0.41	0.33	0.23
3	2 (D1/F2)	0.40	0.17	0.29
3	3 (D2/F1)	0.36*	0.11	0.17
3	4 (D2/F2)	0.35**	0.34	0.11
4	1 (D1/F1)	0.04	0.008	0.02
4	2 (D1/F2)	0.02	0.005	0.01
4	3 (D2/F1)	0.03**	0.012	0.01
4	4 (D2/F2)	0.01*	0.003	0.01
Combined	Combined	15.29	40.33	14.88
* p ≤ 0.05, **p ≤ 0.01, D1 = density 1, D2 = density 2, F1 = normal fertilization, F2 = additional 100 kg N ha^−1 6 weeks after planting.

Table III. Mean squares for stem strength for four treatments combined, for internodes two, three and four for parents and F₁ hybrids.

	Internode 2	Internode 3	Internode 4
Replications	101.28**	0.83*	0.01
Entries	69.21**	0.98**	0.06**
Treatments	215.36**	18.09**	21.03**
Interaction	12.04	0.95	1.14
Error	15.15	0.19	0.01
* p ≤ 0.05, ** p ≤ 0.01.

Figure 1.  Stem strength [(W×D)/L] for the first four internodes (I1–I4) for parents and F₁ hybrids. 1 = SST 57, 2 = SST 55, 3 = SST806, 4 = DH 24, 5 = DH 29, 6 = 3-273, 7 = BX, 8 = SST876, 9 = 36-8. W = breaking weight of internode, D = pith thickness of internode, L = length of internode.

Table IV. Linear correlation between measured stem strength characteristics for internodes two, three and four and combined, over four treatments.

		Plant	Breaking	Internode	Internode	Stem cortex	Pith
	Internode	height	Weight	length	diameter	thickness	thickness
Breaking weight	2	−0.04
	3	0.06
	4	0.22**
	Combined	0.02
Internode length	2	0.59**	−0.40**
	3	0.79**	−0.03
	4	0.82**	0.27**
	Combined	0.27**	−0.69**
Diameter	2	−0.10	0.03	−0.02
	3	0.22**	0.63**	0.28**
	4	0.05	0.02	0.06
	Combined	−0.02	−0.01	0.06
Stem cortex thickness	2	−0.15	0.56**	−0.31**	0.08
	3	−0.12	0.47**	−0.14	0.40**
	4	−0.09	0.30**	−0.05	−0.01
	Combined	−0.09	0.72**	−0.60**	0.02
Pith thickness	2	−0.22**	0.36**	−0.43**	−0.01	0.88**
	3	−0.24**	0.13	−0.34**	−0.22**	0.70**
	4	−0.33**	-0.02	−0.22**	0.02	0.77**
	Combined	−0.15**	0.69**	−0.73**	−0.03	0.89**
Stem strength	2	−0.26**	0.80**	−0.59**	0.01	0.72**	0.69**
	3	−0.32**	0.73**	−0.52**	0.20	0.64**	0.62**
	4	−0.34**	0.62**	−0.31**	−0.01	0.63**	0.50**
	Combined	−0.13**	0.86**	−0.65**	−0.02	0.75**	0.81**
** p ≤ 0.01.