The influence of Meloidogyne incognita on the growth, physiology and nutrient content of Phaseolus vulgaris

Abstract

One-week-old Phaseolus vulgaris cv. Topnotch Golden Wax plants were inoculated with 0, 1000, 5000 or 10 000 freshly hatched Meloidogyne incognita larvae per plant, and maintained under controlled conditions (21 °C, 14 h day at 400 μE m⁻²s⁻¹; 16 °C, 10 h night cycle). At 3 weeks after inoculation, leaf area, dry weight, number of flowers, the total carbon, hydrogen, nitrogen, calcium, copper, iron, manganese, potassium and zinc content of shoots and roots, leaf chlorophyll content, and dark respiration and photosynthetic rates were measured. Respiration rate, percentage shoot nitrogen content, and calcium, copper and iron content (per unit weight and on a shoot: root ratio basis), were significantly increased with increasing inoculum level. Other measured parameters were significantly decreased. Calcium, copper and iron in the shoot and potassium in the root increased per unit weight, while copper and zinc in the roots decreased significantly as a result of nematode infection. However, the overall total content of the nutrient elements per plant was significantly decreased by nematode infection. Differences in the physiology and nutrient content of P. vulgaris plants, as they relate to altered growth and loss of yield of nematode-infected plants, are discussed.