TABLE 3.

Symbiotic performance of R. etli strains with modified nitrogenase expression constructs in greenhouse experiments^a

Strain or treatment	Nitrogenase activityb	Plant dry wt (g plant−1)c	Seed yield (g plant−1)d	N content in seed (mg of N g−1)e
CFN42 (wild type)	64.5 ± 9.2A	0.54 ± 0.13A	1.43 ± 0.13A	33.9 ± 2.3A
HP220(pTR101, nifHDKb)	72.7 ± 12.0A	0.66 ± 0.21AB	1.56 ± 0.32AB	41.4 ± 7.5B
HP210(pTR101, nifHc)	77.3 ± 18.5A	0.75 ± 0.29AB	1.73 ± 0.24A	31.2 ± 3.1A
HP55(pTR101, pr c nifHcDK)	108.2 ± 8.9B	0.81 ± 0.16B	2.50 ± 0.23B	43.6 ± 9.1B
With added N		1.22 ± 0.22C	2.60 ± 0.48B	36.1 ± 2.3AB

^aValues are means ± standard deviations. Different letters represent significant differences (P < 0.05).

^bNitrogenase activity is expressed as micromoles of ethylene hour⁻¹ gram of nodule⁻¹.

^cDry weight was measured at 18 dpi. Ten plants were dried and weighed at 32 dpi.

^dSeed yield from 10 plants (80 days old).

^eSeeds from 5 plants were evaluated.