Author
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Franks, Cleve |
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McMichael, Bobbie |
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Submitted to: Annual Missouri Symposium
Publication Type: Abstract Only Publication Acceptance Date: 5/1/2006 Publication Date: 5/24/2006 Citation: Franks, C.D., Mcmichael, B.L. 2006. Genetic variability for seedling root traits in sorghum [sorghum bicolor (l.) moench][abstract]. Annual Missouri Symposium. Interpretive Summary: Technical Abstract: Sorghum frequently suffers from water-deficit stress in semi-arid environments. It has long been the goal of sorghum improvement programs to increase the inherent drought tolerance of the crop. Although it has been given little attention, rooting capacity may be of great importance in engendering drought tolerance to the crop, since the ability of a genotype to scavenge soil water may contribute to its ability to produce an acceptable yield under conditions of limited water availability. Screening methods suitable for the evaluation of rooting traits in larger breeding programs, however, are not generally available. A series of studies were conducted to: 1) evaluate a diverse set of sorghum germplasm for seedling root traits 2) to develop tools for screening sorghum germplasm for variability in rooting capacity among both exotic and adapted sorghum lines, and 3) to assess the applicability of electrical capacitance measurements to both early and mid-season rooting characteristics. Seeds of two classes of sorghum lines (both adapted and exotic) were germinated in polyethylene growth pouches in a constant temperature (30C) growth chamber and rooting traits were evaluated after four days. Plants from a subset of the forty lines initially examined were also grown in large containers in the greenhouse and electrical capacitance was determined after 30, 42, and 60 DAP using a portable electrical capacitance meter. After the final capacitance readings (60 DAP), the plants were removed from the soil, their toot and shoot dry weight determined as well as the total root length. The actual plant measurements were correlated with the sequential capacitance measurements. The growth chamber results indicate significant differences occurred in taproot length, lateral root length, number of laterals and branching between the adapted and exotic classes with significantly greater means in the exotic class for all variables. There was also significant within-class variability which was also greater for the exotic class. The greenhouse studies indicated a significant positive relationship between the electrical capacitance of the plants at 30 DAP and the total root length of the four day old seedlings grown in the growth pouches. The relationship between the capacitance measurements and the observed plant biomass and root length observations will be discussed concerning the potential of the capacitance techniques as a field screening tool for rooting capacity. |
