INHERITANCE OF SUBCROWN INTERNODE LENGTH IN WINTER BARLEY AND RELATED STUDIES INVOLVING WINTERHARDINESS

The inheritance of subcrown internode length in the winter barley cross NE62203 x MO B2632 was investigated as a component for increasing winter survival. Mean subcrown internode lengths of NE62203 and MO B2632 were 0.2 and 4.3 cm, respectively. F(,2) plants segregated in a continuous distribution except for 13% which were in the 0.0 to 0.5 cm class. Heritability estimates, calculated by the variance of F(,2) plants method and parent-offspring regression of F(,3) family means on F(,2) plants, were 85.3 and 86.9%, respectively. The high heritability of this character indicates that selection for short subcrown-internode length should be effective. Results from generation means analysis showed that additive gene effects accounted for 95.0% of the total genetic variation. However, significant dominance, additive x additive epistasis, and additive x dominance epistasis were also detected. Controlled environment tests investigating a genotype x environment interaction for field winter survival in winter barley were conducted. The variety Kearney dehardened at a faster rate, and had a greater reduction in survival at high crown-moisture contents that the three Nebraska lines tested. The differential effects of crown moisture content on cold injury in the cultivars studied could explain the genotype x environment interaction for field winter survival. Production studies conducted at two Nebraska locations for 3 years demonstrated that winter barley yields obtained with no-tillage were comparable to those obtained with conventional tillage. Fourier (harmonic) analysis was performed on soil temperature data measured at two depths under no-tillage and conventional tillage and temperature prediction equations were computed. Soil temperature fluctuations were smaller and minimum temperatures were warmer with no-tillage compared to conventional tillage. This was due to a more compact soil and the presence of protective residue with no-till. Because minimum soil temperatures at the depth of crown formation with no-tillage were often significantly warmer ((GREATERTHEQ) 2.0 C) than those with conventional tillage, the practice of no-tillage should increase winter survival