Study on Maize Stalk Lodging Resistance in Cyclic Cross Selection

Stalk lodging resistance is a particularly important trait on maize, especially in terms of mechanized harvesting of the crop. Stalk lodging represents a major problem of corn with yield losses. Because of this reason, it takes a special attention on the breeding process. The purpose of this research was the study of maize stalk lodging resistance before the harvest time and finding the best breeding lines for this type of resistance. We used 7 breeding lines (TE 229, TE 202B, TA 452, TE 330A, TD 364, TE 317 and TE 335) as maternal lines and another 3 (TD 268, TC 385A and TC 399) as testers. Lines were tested in 2011 and 2012, in compared cultures with 24 variants, where 21 of them were the experimental hybrids between tested lines and testers and the other 3 werethe control hybrids Turda 201, Turda Favorit and PR39D81. Variance analysis was performed according to the classical model of a two-factor system. Genic effects were calculated after 2nd North Carolina model. Regarding the results, the highest percentage of unbroken plants was on TD 268 tester (80.7%) and the lowest on TD 364 tested line (70.2%). Tested lines that was noted for the general combining ability of lodging resistance were TA 452 and TE 335. Crossings that marked high values for non-additive effects were TA 452 x TC 385A, TE 202B x TC 399 and TE 202B x TD 268. Effects values for general combining ability were between -4.72% and +4.49% on tested lines, -1.68% and +5.78% on testers; effects values for specific combining ability were between -11.25% and +7.58%. Regarding the tested lines was noted TA 452 inbred line and regarding the testers was noted TD 268 inbred line. On this issue, we can state that in the selection process of maize hybrids must be chosen only those hybrid combinations with stalk-lodging resistance because of the similar contribution of additive and non-additive genic effects to resistant genotypes

Germplasm collection – valuable resources of variability for plant and ear traits in maize breeding

Maize is one of the most important crops, both worldwide and in Romania, and preserving the diversity of the biological material used in the breeding of this plant is of particular importance. The Agricultural Research and Development Station (ARDS) Turda, Romania, inbred lines collection includes both its own genotypes and some obtained as a result of germplasm exchanges with other institutions in the country or abroad. In the present study, 575 lines created at Turda were analysed regarding some traits of the plant (plant height, ear height, total number of leaves, number of tassel branches) and the ear (ear length and weight, number of kernel rows and number of kernels/row). The biological material used in this study shows a great diversity: a medium or high variability coefficient was identified for several of the traits analysed (number of tassel branches, ear height, ear height). Frequency histograms were made for the studied lines, for plant and ear traits. A great variability also was observed in the colours of the anther and silk, but also for kernel type and colour and cob colour