|Van santen, Edzard|
Submitted to: Nematropica
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/1/2011
Publication Date: 6/1/2011
Publication URL: http://handle.nal.usda.gov/10113/55238
Citation: Moore, S.R., Lawrence, K.S., Arriaga, F.J., Burmester, C.H., Van Santen, E. 2011. Influence of water movement and root growth on the downward dispersion of rotylenchulus reniformis. Nematropica. 41(1):75-81. Interpretive Summary: The presence of the reniform root nematode (Rotylenchulus reniformis) deep in the soil can affect cotton health. However, very little is known on the vertical movement of nematodes within a soil. Therefore, two laboratory experiments were established with deep soil cores to determine 1) the effect of water infiltration on the vertical movement of the reniform root nematode, and 2) the role of root growth in the downward movement of the reniform root nematode. The first study included four levels of simulated rainfall amounts; 0, 1, 3, and 5 inches of rain. Water infiltration affected the vertical movement of the reniform root nematode through the soil. Nematodes were observed to a depth of 12 inches after the 1-inch rain event, and at 18 inches of depth after the 3-inch rainfall. After the 5-inch rain, nematodes reached the bottom of the soil core of 30 inches. Even though cotton roots reached the bottom of the cores at 60 days after planting, some nematodes reached this same depth in 45 days after planting. Female nematodes only colonized roots to a depth of 24 inches at 90 days after planting. Cotton roots were observed to exhibit less growth when the numbers of female nematodes in the roots was the highest, demonstrating the negative impact of the reniform nematode on root growth.
Technical Abstract: The presence of Rotylenchulus reniformis at depths of greater than 1.5 -m can have negative effects on cotton health. Two trials were established in 7.62 -cm diameter by 75 -cm deep soil cores to determine 1) the effect of water infiltration on vertical translocation of R. reniformis, and 2) the role of root growth in the downward migration of R. reniformis. The water infiltration study consisted of three treatments of simulated rainfall amounts, 25.4 -mm, 76.2 -mm, and 127 -mm, and no rainfall. Water infiltration minimally affected the movement of R. reniformis through the soil profile. Nematodes were observed to a depth of 30 -cm after the 25.4 -mm rain event. Rotylenchulus reniformis was detected to a depth of 45 -cm following 76.2 -mm of rainfall and to the maximum sampling depth of 75 -cm following 127 -mm of rainfall. Cotton roots reached the maximum depth of 75 -cm at 60 days after planting (DAP). Vermiform life stages reached 75 -cm at 45 DAP. Females colonized roots to a depth of 62 -cm at 90 DAP. Cotton roots were observed to exhibit less growth when the numbers of females embedded in the roots was the highest, illustrating the deleterious effects on root production by R. reniformis.