Response of improved groundnut lines to late leafspot disease

Abstract

Foliar fungal diseases account for over 80% reduction in groundnut productivity in most parts of Uganda. Late leaf spot (LLS) caused by Cercosporidium personatum Deighton. Spots of late leaf spot are black and usually without yellow halo. Spread and severity is influenced by the field cropping history, temperature, and relative humidity, the leaf spot disease epidemics, Genetic variation exists in cultivated groundnut for LLS resistance, but the resistant genotypes are generally late maturing. Direct selection for leaf spot resistance in groundnut is also difficult and has been reported to be associated with low yield, poor pod, and kernel characteristics and late maturity. As a result, there is the need to consider other physiological traits that can confer tolerance to the two foliar diseases and enhance pod and haulm yields. This research study assessed 50 selected groundnuts lines for late leaf spot resistance and high yield in Uganda. The main objective of the study was to determine the response of improved groundnuts varieties to leaf spot severity Specific objectives were: To determine the effect of late leaf spot on groundnut yield (pod / seed, haulm). To determine the level of resistance to late leaf spot across the groundnuts genotypes (three selected botanicals of groundnuts) The research study was conducted for two (2) consecutive seasons in the first rains of 2022, season (2022A) and the second rains of 2022; season (2022B) This study was to determine the influence of leaf spot disease severity on selected groundnuts lines in terms of yield (pod, seed, and haulm). Fifty (50) groundnut genotypes with varying degrees of tolerance to leaf spot were evaluated under marginal environments in the field, each of the genotype was planted in 5 X 10 alpha lattice design a 3 row plot measuring 1.5x 1.5 meters using a spacing of 45cm x 10 cm in both season A and B year 2022 at NaSARRI Uganda. Data collection accounted to all the plants per plot at the start of the experiment Disease severity was assessed at weekly intervals for 12 consecutive weeks. Data on yield and yield component such as, number of pods per plant, and 100 seed weight (grams/kilograms), plant stand, 50% flowering, was collected at 7 days’ interval. The severity of LLS infection was scored on a scale of 1 to 9 with 1 being completely resistant and 9 a dead plant.