Grain Yield and Yield Components of Field Pea (Pisum sativum L.): As Influenced by Ascochyta Blight (Mycosphaerella pinodes) Disease in the Highlands of Bale, Oromia

Abstract

Field pea or “dry pea” (Pisum sativum L.) is an annual cool-season food legume which grows worldwide and is the second major pulse crop produced in the highlands of Bale next to Faba bean. The experiment was conducted for two consecutive cropping seasons; 2011/12 and 2012/13 at Sinana agricultural research center (SARC) on-station research site. The objective was to investigate the effect of Ascochyta Blight (Mycosphaerella pinodes) disease on field pea yield and yield components. Local field pea cultivar was used with a fungicide Benomyl at a rate of 2.5kg/ha and four application schemes (spraying at 7 days, 14 days and 21 days interval and no fungicide spray) arranged in RCB Design with 3 replications. The logistic model (ln[y/ (1-y)]) was employed for estimation of the disease progression and the data were analyzed using SAS procedure. The association of disease parameters with yield and yield components were assessed using Regression and correlation techniques. ANOVA for disease severity, AUDPC and disease progress rate (r) have shown significant difference (P<0.0001) between treatments. The highest Ascochyta blight disease severity of 40.12% was recorded from non treated plot; while the lowest severity of 12.96%, was recorded from plot sprayed at 7 days interval. Similarly, the highest AUDPC of 1432.41%-days and the lowest (434.25%-days) were recorded from non-treated and plot sprayed at 7 days interval, respectively.

In the same way, the highest disease progress rate (r) of 0.036771 units-day^-1 and the lowest r of -0.007652 units-day^-1, respectively were recorded from non-treated plot and plot sprayed at every 7 days interval, respectively. ANOVA for yield and yield components have shown significant difference (P<0.05) between treatments. For all of the parameters considered, the highest values were recorded from plots sprayed every 7 days interval; while the lowest were from none sprayed plot. The highest (195.81g) and the lowest (175.23g) TKW were recorded from plots sprayed at 7 days interval and none treated plots, respectively. While the highest (2945.6 kg/ha) and the lowest (1873.5 kg/ha) grain yield were recorded from plots sprayed at 7 days interval and none treated plots, respectively. The linear regression of disease severity with grain yield revealed that there was highly significant difference (P<0.0001) between treatments. The estimated slope of the regression line obtained for Ascochyta blight disease severity was -39.08. Which indicates that, for every unit increase in Ascochyta blight disease severity there will be a reduction of 39.08 kg/ha in Field pea grain yield. Correlation analysis has shown that Ascochyta blight disease have highly significant strong negative correlation with grain yield (r = -0.84400, P<0.0001). Similarly, grain yield have significant strong negative correlation (r = -0.83841, P<0.0001) with AUDPC.