Wednesday, November 15, 2006 - 10:30 AM

Evaluation of Lablab for Root-knot Nematode Resistance.

G. R. Smith1, F. M. Rouquette Jr.1, and J. Starr2. (1) TAMU Ag'l. Res. & Ext. Ctr., PO Box 200, Overton, TX 75684, (2) Texas A&M University, College Station, TX 77843

Lablab (Lablab purpureus) is a drought tolerant summer annual legume that is used throughout the tropics as a forage, hay and green manure crop. Southern root-knot nematodes (Meloidogyne incognita) are a harsh pest of warm-season forage legumes, with infestations on susceptible host plants causing severe damage to root systems. Experiments were conducted in 2004 and 2005 to evaluate the reaction of lablab to southern root-knot nematode. Lablab breeding lines and the check cultivar Rongai were inoculated with southern root-knot nematode, evaluated and compared to Iron and Clay cowpea (Vigna unguiculata) under greenhouse conditions. In 2004, average gall scores (0 to 5 with 5 = severe galling) ranged from 1.3 to 4.7 for Iron and Clay cowpea and TX41-97 lablab, respectively.  Average nematode egg production ranged from 410 to 33,639 eggs per g root fresh weight for Iron and Clay cowpea and TX41-97, respectively. The best lablab line was TX35-03 with a 2.3 gall score and 6696 eggs per g root fresh weight. One plant of TX35-03 was noted with no galling and only 26 eggs per g of root fresh weight. In the 2005 reevaluation, TX35-03 was again the best lablab line with a gall score of 1.1. In the 2005 study, Rongai had the most severe galling of all the lines evaluated.