Combining management and breeding advances to improve field pea (Pisum sativum L.) grain yields under changing climatic conditions in south-eastern Australia

Abstract

Field pea (Pisum sativum L.) is widely grown across southern Australia. Delayed sowing is recommended to minimise yield losses caused by the disease ascochyta blight. However, drier and hotter springs in recent seasons have resulted in greater yield penalties from delayed sowing than from this disease. Field pea breeding in these shorter growing seasons has rapidly shifted the selection intensity towards genotypes with earlier flowering. Research was conducted to identify optimal management strategies that reduce losses from both disease and delayed sowing. Experiments comprising differing sowing dates (conventional, and 2–3 and 4–6 weeks earlier), various genotypes (including Alma—tall trailing type, and Kaspa—semi-leafless erect and OZP0602—earlier flowering, semi-leafless) and six fungicide treatments (combinations of P-Pickel T® seed dressing and mancozeb foliar fungicide) were conducted in multi-location sites in South Australia from 2007 to 2009. Ascochyta blight infection occurred in all years irrespective of treatment and location, but only reduced grain yield in one experiment in 2008 and two in 2009. The two earlier sowing dates were generally higher yielding than the conventional sowing date for all genotypes. However under severe disease pressure yield loss was observed with the earliest sowing date. Genotype differences were also observed in terms of yield response to sowing date and in levels of disease infection, although these small improvements in disease resistance did not translate to a yield advantage. The combination of seed treatment and strategic foliar fungicides resulted in a positive yield response in 2009 but this was variable between sowing dates and genotypes. Under recent weather patterns of lower rainfall and shorter growing seasons, this study suggested the optimum planting period is within a week of the first autumn rains in low rainfall regions and 3 weeks after the first autumn rains in medium and medium–high rainfall regions. Grain yield can be optimised in these conditions by using earlier flowering genotypes together with strategic fungicide application and early time of sowing. These earlier flowering genotypes were also found to have broader adaptation to a range of sowing dates providing increased management flexibility. Fungicides with greater efficacy than mancozeb are required to maximise yield at the earliest sowing time.