Table I.

Grain-filling rate and grain yield of wheat subjected to various N and soil moisture treatments

Treatment	Active Grain-Filling Period	Grain-Filling Rate	Spike Number	Grain Number	Kernel Weight	Grain Yield
	d	mg grain−1 d−1	spike m−2	grain spike−1	mg grain−1	g m−2
NN + WW	27 ba	1.40 c	419 a	41 a	42 b	701 b
NN + WD	19 d	1.94 a	417 a	40 a	41 b	679 b
HN + WW	34 a	0.95 d	424 a	42 a	36 c	628 c
HN + WD	24 c	1.69 b	421 a	43 a	45 a	785 a

The treatments are NN + WW, well watered with normal amount of nitrogen; NN + WD, water deficit with normal amount of nitrogen; HN + WW, well watered with high amount of nitrogen; and HN +WD, water deficit with high amount of nitrogen. Active grain-filling period and grain-filling rate were calculated according to Richards' (1959) equation. Values of spike number per square meter, grain number per spike, and grain weight were means of plants harvested from 2 m² of each treatment. The grain yield was the means of plants harvested from 18 m² of each treatment. Statistical comparison was within the same column.

^aDifferent letters indicate statistical significance at the P = 0.05 level of probability.