Biological and Agrotechnical Aspects of Weed Control in the Cultivation of Early Potato Cultivars under Cover

Problems with weed infestation under cover were the reason to conduct research on the regulation of weed infestation in potato cultivation for early harvest. The field experiment was carried out in 2015–2017 at the Experimental Station for Cultivar Assessment in Uhnin (51°34′ N, 23°02′ E) using the method of random subblocks, in a dependent system (split-split-plot). The first order factor was edible potato cultivars ‘Denar’ and ‘Lord’. The second order factor was cultivation technologies: (A) traditional technology, (B) technology using polyethylene film cover, (C) technology using polypropylene agrotextile. The third order factor was weed management methods: (1) mechanical, (2) mechanical and chemical method using Afalon Dispersion 450 SC preparation, (3) mechanical and chemical methods using Racer 250 EC herbicide, and (4) mechanical and chemical methods using a mixture of herbicides Afalon Dispersion 450 SC and Command 480 EC. Mechanical and chemical methods proved to be more effective than the mechanical method. The best effectiveness in limiting both fresh and dry weed mass in potato cultivation under cover was achieved using the mechanical and chemical method using a mixture of herbicides, Afalon Dispersion 450 SC and Command 480 EC.

Influence of cultivation technology on the color of raw potato tubers

Results of the research were based on a field experiment carried out in 2014‒2016 at the Experimental Station of Cultivar Assessment in Uhnin (51°34'N, 23°02'E), on podzolic slightly acidic soil. The experiment was carried out using random sub-blocks, in a dependent split-plot system, in triplicate. The first-order factor was potato cultivars (‘Vineta’ and ‘Satina’), and the second-order factor consisted of six cultivation technologies: A − using fungicides to control potato blight, technologies: B, C, D, E − with the application of effective microorganisms, and technology F − without the use of fungicides and effective microorganisms as a control object. The scope of the research included assessing the color of the raw tubers pulp. To determine the color of raw potato, the method of trichromatic colorimetry was used applying the Konica Minolta CM-5 spectrophotometer. The color measurement of raw tubers was carried out in the CIEL*a*b* system. Cultivation technology with fungicide application significantly contributed to the brightness change of the raw tuber flesh compared to the technology (D), where for the treatment, as in the growing season, effective microorganisms were used. Genetic properties of cultivars determined the color brightness, as well as its trichromatic coordinates.

Effect of Mild Treatments on Some Physicochemical and Pasting Characteristics of Flour from Two Cocoyam Cultivars

Effect of mild treatments namely; one-step annealing (AN), partial-nixtamalization (NIX) and phenolic-admixture (VAN) on some physicochemical and pasting characteristics of flour prepared using two cocoyam cultivars was studied. Both annealing treatment and phenolic admixture resulted in high peak viscosities (PVANwhite = 322.50 RVU; PVVAN = 306.67 RVU) of samples comparative to low peak viscosity white = 227.25 RVU) of the control for white cultivar. Similarly, the peak viscosities (PV red = 310.70; PVVANred = 296.45) of samples were higher than the peak viscosity (PVred = 225.42 RVU) of the control for red cultivar. Assessment revealed positive set back viscosities (SBVAN = + 9.30 RVU; SBVAN = + 21.33 RVU) for both the varieties after annealing treatment. Partial- NIX treatment showed molecular depolymerization. Interaction of treatments at levels employed in this study showed no synergistic effect. The pH of treated and control samples were within low acid range for foods. Mild treatment could be useful for tempering cocoyam flour for preparation of bakery and similar pasta products.

A METHOD FOR ASSESSING REGIONAL TRIAL DATA WHEN THE TEST CULTIVARS ARE UNBALANCED WITH RESPECT TO LOCATIONS

A method for assessing regional trial data when test cultivars are not balanced over all locations is proposed. The method is designed primarily for analyzing Eastern cooperative trial data in which the first year’s cultivars are tested only in the subregion (province) where they were developed. Two parameters are estimated for each cultivar: the superiority measure (P), defined as the mean square distance between the cultivar’s response and the maximum response, averaged over the locations where it was tested; and the projected cultivar mean based over all locations on the regression model for genotype × environment interaction. The first parameter indicates how close the response of a cultivar is to the maximum, and the second parameter estimates what the overall performance would have been had cultivars been balanced over all locations. The selection criterion is the P-value, while the projected mean is supplementary; its function is to check if the estimated P-value is realistic. When the rank of the P-value differs considerably from that of the projected mean, investigation of the data by plotting is necessary.Key words: Unbalanced two-way classification data, cultivar assessment, regional trial, superiority measure

A SUPERIORITY MEASURE OF CULTIVAR PERFORMANCE FOR CULTIVAR × LOCATION DATA

A measure of cultivar general superiority for cultivar × location data is defined as the distance mean square between the cultivar’s response and the maximum response averaged over all locations. Since the maximum response is the upper boundary in each location, a small mean square indicates general superiority of the test cultivar. The method requires that all test cultivars be balanced over locations but not necessarily the checks. The advantage of the proposed method are: (i) The checks provide only a plausible maximum response for each location and are not required for assessing the test cultivars. Thus checks do not have to be present in all locations. This allows a greater flexibility for a breeder to choose locally adapted cultivars as checks without unduly increasing the size of a regional trial. (ii) The measure of general superiority consists of only one parameter, thus simplifying the screening process considerably. A subsidiary parameter for interaction can be used to indicate lack of general adaptability. (iii) The difference between the mean of the maximum response averaged over all locations and the mean of the best cultivar provides useful information as to how many cultivars are needed to achieve optimum productivity for the entire region, (iv) The specific adaptability of a cultivar can be identified by plotting the maximum and the test cultivar responses on the location means.Key words: Genotype × environment interaction, cultivar assessment, regional trial

PROCEDURAL APPROACH FOR ASSESSING CULTIVAR-LOCATION DATA: PAIRWISE GENOTYPE-ENVIRONMENT INTERACTIONS OF TEST CULTIVARS WITH CHECKS

A simple procedure for assessing cultivar-location data is proposed. The procedure consists of comparisons between checks and each of the test cultivars to find those test cultivars for which comparison with the checks can be done ignoring variability among locations, and to isolate those for which a location-by-location comparison is advisable. Since the level at which a comparison-wise genotype-environment interaction is deemed to be important can be set by the user, this represents a great simplification of the assessment process. A set of regional trial data was used as an example to demonstrate the approach. The complementary nature of this method with cluster analyses which group cultivars or locations is discussed.Key words: Genotype-environment interaction, cultivar assessment, barley yield