Identification of Elite Potato Clones with Resistance to Late Blight Through Participatory Varietal Selection in Peru

Potato is the most important crop in Peru and late blight is the main disease affecting the crop. However, new varieties that are resistant to late blight often lack other traits that farmers and consumers prefer. Using participatory varietal selection, this study seeks to identify clones with high potential to become varieties with resistance to late blight but also feature a high marketable tuber yield and other preferred agronomic traits. During 2016–2017, 36 clones previously selected for high levels of resistance to late blight from population B developed by the International Potato Center, and three varieties used as controls (INIA 302 Amarilis moderately resistant, INIA303 Canchan and Yungay susceptible to late blight), were evaluated in five Peruvian locations. At harvest, five clones were selected based on (i) evaluations made by farmers through Participatory Varietal Selection, (ii) analysis of mixed models and Best Linear Unbiased Predictors for tuber yield, (iii) low glycoalkaloid content in tubers, and (iv) good organoleptic quality. These clones were evaluated again during 2017–2018 in four locations. Resistance to late blight and good marketable tuber yields were identified as the most important criteria for the selection of a new potato variety. The clones CIP308488.92, CIP308495.227 and CIP308478.59 were selected as promising clones having resistance to late blight and tuber yield superior to the local varieties, INIA-303 Canchan, Yungay, as well as good organoleptic quality and low glycoalkaloid content. These clones can be suggested for variety release in similar agroecological environments.

Effect of genotype, flesh colour and environment on the glycoalkaloid content in potato tubers from integrated agriculture

The main aim of the study was evaluation of the content of -solanine, -chaconine and total glycoalkaloids (TGA) in fourteen new potato cultivars with purple and red flesh in comparison with yellow- and white-fleshed control potatoes cultivated in a friendly way in integrated agriculture. The results were obtained from three-year trials on two locations. TGA levels in tubers’ flesh ranged from 33.69 to 167.77 mg/kg fresh matter (FM), and the ratio of α-chaconin to α-solanin from 1.18 to 3.78. No TGA safety limit was exceeded for any cultivar. The glycoalkaloids content was not significantly influenced by flesh colour, whereas the cultivar genotype had a decisive influence on their content. Eight cultivars with coloured flesh yielded a more favourable lower TGA content in comparison with the yellow-fleshed control cv. Agria (86.3 mg/kg FM); on the contrary six cultivars showed higher TGA values. The highest average TGA content was found in the purple-fleshed Bora Valley cultivar (165 mg/kg FM), the lowest was found in the red-fleshed Red Emmalie cultivar (43.6 mg/kg FM), whereas the white-fleshed cv. Russet Burbank reached 67.0 mg/kg FM. The glycoalkaloid content was significantly affected by location and year weather conditions.

Heritability for Yield and Glycoalkaloid Content in Potato Breeding under Warm Environments

High temperatures affect potato production in the tropics, putting tuber yield and quality at risk and leading to increased glycoalkaloid concentration the cause of the bitter taste in potatoes and a cause for concern for human health. The International Potato Center (CIP), has developed new heat tolerant clones which are heat tolerant and also resistant to late blight. These clones offer an opportunity to evaluate yield and glycoalkaloid levels after growth under high temperature environments. We evaluated four sets of 16 full-sib families and 20 clones for tuber yield and glycoalkaloid content in order to estimate narrow-sense and broad-sense heritability respectively. We used a randomized complete block design replicated in three locations in Peru; San Ramon, La Molina and Majes At harvest, the number and weight of marketable and nonmarketable tubers were recorded. We analyzed samples of tubers from each clone for glycoalkaloid content using spectrophotometry. Narrow-sense heritability for tuber yield, tuber number and average tuber weight were 0.41, 0.50 and 0.83, respectively, indicating that further gains in breeding for heat tolerance will be possible. Broadsense heritability for glycoalkaloid content was 0.63 and correlation with tuber yield was weak, r=0.33 and R²=0.11 (P<0.01). High heritability and weak correlation will allow us to select clones with high tuber yield and low glycoalkaloid content, to serve as candidate varieties and parents in breeding programs.

Effect of soil conditioner (UGmax) application on the content of phenols and glycoalkaloids in potato tubers

The objective of the study was to determine the effect of the soil conditioner UG_max application on phenol and glycoalkaloid content in the tubers of two table potato cultivars. The following factors were examined: factor I − cultivars: Satina and Tajfun; factor II − five application methods of the soil conditioner UG_max: (1) control − no UG_max application; (2) 1.0 L/ha UG_max before planting; (3) 0.5 L/ha UG_max before planting + 0.25 L/ha at potato height of 10–15 cm + 0.25 L/ha in flower bud phase; (4) 1.0 L/ha UG_max before planting + 0.50 L/ha at potato height of 10–15 cm + in 0.50 L/ha in flower bud phase; (5) UG_max applied after emergence when plants were 10–15 cm high at the rate of 0.5 L/ha, and at the stage of flower buds at the rate of 0.5 L/ha. The highest concentration of phenols and glycoalkaloids was recorded in plots where UG_max was applied prior to potato planting at the rate of 1.0 L/ha, when plants were 10–15 cm high at the rate of 0.5 L/ha and at the stage of flower buds at the rate of 0.5 L/ha.