Corn stalk traits related to lodging resistance in two soils of differing salinity.

Abstract

Stalk lodging is one of the most serious problems in corn (Zea mays L.) production. The use of effective criteria in selecting hybrids resistant to lodging would contribute greatly to yield stability. Objectives of this work were to evaluate various stalk traits of corn hybrids to determine which could be effective criteria for selecting genotypes resistant to lodging. Furthermore, realization of the increasing soil salinity in the irrigated areas of Greece led to an investigation of corn lodging behavior in such soils. Ten dent-kernel-type corn hybrids of late maturity were tested during 1993 and 1994 in two locations differing in soil electrical conductivity. The soil with 0.655 dSm -1 conductivity is characterized as normal for corn growth and the soil with 3.22 dSm -1 suffers incipient salinity. A randomized complete block design with five replications was used in all experiments. The stalk traits measured were mechanical (rind puncture force, crushing and breaking strength forces), morphological (plant-to-1st-ear-height ratio, stalk diameter, weight, and density) and chemical (sugars, lignin. N, K, and Na concentrations). Lodging was greater (mean value over hybrids 64%) in the soil with the incipient salinity problems compared to normal soil (38%). Grain yield was negatively correlated with lodging percentage (r=-0.77 ** and -0.72 ** for soils with normal conductivity and with incipient salinity, respectively). Ranking of hybrids according to percentage of lodging was similar in the two locations. All the mechanical and morphological traits except stalk density, and lignin concentration among chemical traits, showed lower values in the soil with increasing salinity, while stalk density, sugars, and K and Na concentrations were higher. Stalk nitrogen concentration was not affected by the soil salinity. Percentage of lodging was significantly correlated only with mechanical traits. In the soi with normal electrical conductivity, the correlation coefficients between the percentage of lodging plants with force of rind puncture was -0.88 ** , crushing strength -0.83 ** and breaking strength -0.81 ** . The corresponding values of the above coefficients for the location with increasing salinity were -0.84 ** , -0.68 * and -0.57, respectively. None of the morphological and chemical traits showed any relation with lodging resistance of the hybrids. The results indicated that resistance to stalk lodging is mainly determined by the strength of the rind and hybrids selected for lodging resistance under soil conditions with normal electrical conductivity will also perform well in soils with incipient salinity problems.