Graphical analysis of multi-environmental trials for wheat grain yield based on GGE-biplot analysis under diverse sowing dates

Table 4 Results from stepwise regression analysis for predicting grain yield of wheat varieties evaluated in eight sowing dates

Sowing dates	Variables entered	Parameter estimate	Partial R²	Model R²	F
6^th September	NSP	0.0129	0.9701	0.9701	357.46^**
	HI	15.8781	0.0222	0.9924	29.19^**
	TGW	0.0619	0.0042	0.9966	11.09^**
	NGSP	-0.1507	0.0013	0.9979	5.17^*
	BY	-0.1201	0.0014	0.9993	13.78^**
	Intercept				100.05^**
6^th October	NSP	0.0050	0.9633	0.9633	289.10^**
	NGSP	0.0587	0.0126	0.9759	5.24^*
	TGW	0.0454	0.0169	0.9928	21.25^**
	BY	0.1771	0.0023	0.9952	3.86^n.s
	HI	7.1900	0.0030	0.9982	11.87^*
	Intercept	-6.3423			95.25^**
6^th November	NSP	0.0041	0.9455	0.9455	190.87^**
	NGSP	0.1021	0.0480	0.9935	73.96^**
	BY	0.2263	0.0045	0.9980	20.90^**
	HI	6.5005	0.0011	0.9992	10.90^*
	Intercept	-5.8101			101.81^**
6^th December	NSP	0.0096	0.8970	0.8970	95.79^**
	NGSP	0.0649	0.0911	0.9881	76.47^**
	Intercept	-1.5232			34.38^**
6^th January	BY	0.3202	0.9976	0.9976	70.17^**
	NSP	0.0016	0.0019	0.9995	21.35^**
	HI	10.5209	0.0000	0.9995	31.02^**
	TGW	0.0047	0.0003	0.9998	8.32^*
	Intercept	-4.1575			1040.74^**
6^th February	NGSP	0.1369	0.9266	0.9266	138.79^**
	BY	0.1605	0.0673	0.9939	110.63^**
	Intercept	-1.8553			83.92^**
6^th March	NGSP	0.0822	0.9243	0.9243	109.86^**
	NSP	0.0064	0.0703	0.9946	103.73^**
	TGW	0.0207	0.0026	0.9972	6.55^*
	Intercept	-1.6423			38.71^**
6^th April	NGSP	0.0756	0.7407	0.7407	14.28^*
	BY	0.0833	0.2558	0.9964	286.55^**
	Intercept	-0.5402			213.16^**

BY Biological yield, GY Grain yield, HI Harvest index, NGSP Number of grains per spike, NSP Number of spikes per m², TGW Thousand grain weight
^* and ^** significant at the 0.05 and 0.01 probability levels, respectively
n.s: not significant

ISSN: 1471-2229