Ammonia Volatilization from Urea-Application Influenced Germination and Early Seedling Growth of Dry Direct-Seeded Rice

Table 3

Seed germination percentage, shoot fresh weight, root fresh weight, and root tip number of rice variety Apo grown in three different soils with ammonium sulfate, urea, and urea + NBPT in comparison with zero N input (control) in Petri dish incubation experiment 2. The presoaked seeds were not in contact with soil but exposed to ammonia gas volatilized from soils.

Parameter	Control	AS^a	Urea^a	Urea^a + NBPT^b
Soil I
Seed germination percentage (%)	100 a	98 a	90 a	100 a
Shoot FW (g per Petri dish)	0.16 a	0.17 a	0.15 a	0.15 a
Root FW (g per Petri dish)	0.17 a	0.14 b	0.01 c	0.15 ab
Root tip number per Petri dish	22 b	32 a	2 c	23 b
Soil II
Seed germination percentage (%)	100 a	98 a	94 a	100 a
Shoot FW (g per Petri dish)	0.15 a	0.17 a	0.15 a	0.17 a
Root FW (g per Petri dish)	0.14 a	0.12 a	0.05 b	0.15 a
Root tip number per Petri dish	27 a	26 a	5 b	23 a
Soil III
Seed germination percentage (%)	100 a	94 a	98 a	98 a
Shoot FW (g per Petri dish)	0.14 b	0.16 b	0.19 a	0.16 b
Root FW (g per Petri dish)	0.12 b	0.07 c	0.07 c	0.15 a
Root tip number per Petri dish	24 b	7 c	5 c	27 a

Within a row, means followed by different letters are significantly different at 0.05 probability level according to Least Significant Difference (LSD) test.
^aThe rate of ammonium sulfate and urea was 0.15 g N per Petri dish.
^bThe rate of NBPT was 1.5 mg per Petri dish.