The hypothesis here proposed is that, in primary fields of mass selection (F1) of sugarcane, herbicides exert a selective action when applied in the early post-emergence of seedlings (POST-i) and supplemented after their establishment phase (POST-l) even in sandy soils. To verify such hypothesis, the selectivity of herbicides was studied on seedlings of three sugarcane families, after their application both at early and late post-emergence in primary selection fields (F1). The field had a randomized blocks design, with five replications, and the subdivided plots scheme was used. Twelve herbicide treatments were allocated in the plots (27 m-2), whereas the sub-plots (9 m-2) contained three families of seedlings. Each sub-plot consisted of a transplanted row (0.5 x 1.50 m) with 12 individuals of the same family. Six treatments were employed, namely, T1: tebuthiuron (1200 g ha-1) post-i + ametryn (3000 g ha-1) post-l; T2: diuron (1404 g ha-1) + hexazinone (396 g ha-1) post-i + ametryn (3000 g ha-1) post-l; T3: sulfentrazone (800 g ha-1) post-i + ametryn (3000 g ha-1) post-l; T4: diuron (1404 g ha-1) + hexazinone (396 g ha-1) post-i + metribuzin (1920 g ha-1) post-l; T5: sulfentrazone (800 g ha-1) post-i + metribuzin (1920 g ha-1) post-l, and T6: weeded plot. The sugarcane families were: F400 (♀IAC086155 x ♂unknown), F43 (♀IACBIO264 × ♂IAC911099), and F14 (♀IACSP991305 × ♂GlagaH). We concluded that the herbicides tebuthiuron (1200 g ha-1), diuron (104 g ha-1) + hexazinone (396 g ha-1), or sulfentrazone (800 g ha-1), when applied in the early post-emergence and supplemented with ametryn (3000 g ha-1) or metribuzin (1920 g ha-1) in late post-emergence (60 days from planting) of the sugarcane families studied, were selective to the seedlings. That is, no toxicity symptoms with a potential to impede the final selection of seedlings occurred.

The aim of the present study was to compare the selection performed by the sum of standardized variables index (Z Index) with the selection based only on the grain yield character, to verify if the grain yield alone is a good alternative for the selection involving multiple characters. The experiments were conducted in Lavras-MG and in Lambari-MG, during the 2015/2016 agricultural year. The used design was the randomized complete block design with 3 replications. Thirty-six genotypes of the preliminary trial of upland rice breeding program of the Federal University of Lavras were evaluated. In order to compose the Z index, the following characteristics were evaluated: grain yield, height, number of days for flowering, 1000-grain weight, income, yield, leaf blast incidence, and grain length/width ratio. Z index was efficient in the selection for multiple characters whereas not all lines with the highest grain yield obtained good results in the other desirable characteristics, indicating that the selection based only on grain yield is not efficient when working with several characters of interest in upland rice cultivation.

This study aimed to verify the efficiency of multilines in reducing blast progress and their potential benefits to phenotypic stability in rice. The experiments were conducted in the 2016/17 and 2017/18 agricultural years. A randomized block design was performed with three replications, evaluating 12 lines and a multiline, which consisted of five lines from the Cultivation and Use Value (CUV) test. The multiline presented an estimated grain yield above the average of experiments of around seven bags ha-1 and superior performance in early flowering, justifying the high phenotypic stability for these characters. In this case, the line selection for composing the multiline was favorable and efficient, highlighted by a higher agronomic performance than most lines of the CUV test. The multiline is an adequate strategy to provide higher phenotypic stability and reduce blast progress in the field.