Chickpea in wheat-based cropping systems of northern New South Wales. II. Influence on biomass, grain yield, and crown rot in the following wheat crop

Abstract

Rotational effects of chickpea, an important N2-fixing pulse legume of the northern grains region, on subsequent wheat require quantification of the contribution of the legume to soil N and the N status of the wheat, and of suppression of soil and stubble-borne pathogens, such as crown rot (Fusarium graminearum Schwabe Group 1). Results from selected treatments of 10 experiments in northern New South Wales in which chickpea and wheat in one season were followed by wheat in following seasons indicated generally higher dry matter (DM) and grain yields of wheat after chickpea than after wheat. Responses to chickpea were -0·8 to 3·3 t/ha (shoot DM) and -3 to 39 kg N/ha (shoot N). Responses in wheat grain yields were -0·1 to 1·7 t/ha (mean 0·85 t/ha); grain N responses were -2 to 33 kg/ha (mean 19 kg/ha). Grain protein responses were small (0·6%) and variable. Although these productivity responses could be explained largely in terms of additional nitrate-N following chickpea, we measured reduced incidences of crown rot in wheat after chickpea (range 1-36%, mean of 12%), compared with wheat after wheat (range 5-52%, mean 30%). Modelling the incidence of crown rot indicated highly significant interactions between prior crop and total water (pre-plant soil water plus in-crop rainfall). When wheat followed chickpea, incidence of the disease declined sharply with increasing water. When wheat followed wheat, there was a marginal decline in disease incidence with increasing water. Our results support the strategy of using legumes in rotation with wheat in the northern grains region for enhanced soil-N supply and disease-break effects.

Cultural Practices Influencing Biological Management of Crop Diseases

“…In another investigation, crown root rot of wheat caused by Fusarium graminearum was reduced and wheat yield increased by a chickpea-wheat versus wheat-wheat rotation. The mean incidence of crown rot was 12 % for chickpea-wheat rotation, compared with 30 % infection in wheat-wheat system (Felton et al 1998 ) . The effect of crop rotation including canola, lupine, medic, medic-clover mixture on the incidence of wheat crown root rot disease was investigated.…”

Forecasting the risk of crown rot between successive wheat crops

“…Mean monthly temperatures were tested because of the reported association between temperature and infection (Wildermuth and McNamara 1994). Felton et al (1998) reported that soil moisture at sowing was related to incidence of disease at the end of the season. Soil moisture was not measured in most crops at Moree, so the soil moisture model in the DYMEX software package (Maywald et al 1999) was used to estimate stored moisture.…”

“…Crown rot is an example of a polyetic disease (Zadoks 1999) in which the epidemic develops over successive years and the incidence of disease in 1 year is influenced by the incidence in the previous year. Some of the published work on crown rot has failed to take this into account, and comparisons between management treatments have been made in 1 year without considering the previous history of the disease (Felton et al 1998). Developing a full-scale predictive system for crown rot will require an understanding of the mathematical nature of polyetic changes in disease incidence.…”

Impact of increasing temperature on the fitness of Fusarium pseudograminearum causing crown rot in wheat

“…Rotation using resistant crops or pastures is another recommended practice for reducing inoculum of the crown rot fungus (Burgess et al, 1996, Felton et al, 1998. In northern New…”

“…South Wales, Felton et al (1998) compared crown rot disease incidence of wheat, which followed chickpea rotation, and wheat which followed wheat. The authors reported reduced incidence of crown rot in wheat after chickpea, compared with wheat after wheat, which supports a large number of observations and studies that show the beneficial effects of a break crop.…”