Fava Bean Cultivation Time and Methods as an Annual Herb and the Causes of Flower and Pod Drop

Fava bean is also called nandou, hudou, shudou, and fodou. It is an annual herb, 30-100 (120) cm tall. It is a crop used for grain, vegetables, feed, and green manure. So when should fava beans be planted? What are the methods? What causes flower and pod drop?

When should fava beans be planted?

1. Generally, spring fava beans in northern and northwestern regions are sown from early March to mid-April; autumn fava bean areas in the south sow in October, that is, mid-October in the lower reaches of the Yangtze River, late October in the middle reaches, late October in South China and Zhejiang, and Yunnan and Guizhou have three-dimensional agriculture, with sowing periods in different regions ranging from September to October, and the largest sown area is in early to mid-October.

2. In bean-growing areas at an altitude of 1550—1700m, fava beans are normally suitable for sowing from October 5—15; in bean-growing areas at an altitude of 1750—1900m, sow from October 10—20; in areas at an altitude of 1950—2200m and above, sow from October 15—25.

What are the fava bean cultivation methods?

1. Select good varieties: For fava beans, choose excellent varieties with high yield, good quality, and strong disease resistance, with local large white hudou being the best.

2. Fine land preparation: Fava beans like moisture but are not tolerant of waterlogging, so choose fertile soil and a sunny plot for planting. After the previous crop is harvested, plow and level the land. For winter fallow fields, open the surrounding ditches and bed ditches well, and make deep ditches and high beds according to the specifications of bed width 1-1.5 m, bed height 25 cm, and ditch width 35 cm, then rake the bed surface level so that the ditches are connected and no water accumulates.

3. Reasonable fertilization: Mainly use farmyard manure and phosphorus and potassium fertilizers. Generally, use 1000-1500 kg of pig and cattle manure, soil miscellaneous fertilizer, or compost, 30-35 kg of superphosphate, and 100 kg of plant ash per mu, mix them as base fertilizer, and apply them in holes after sowing to cover the seed; when the seedlings reach 5-6 true leaves, use 5 loads of decomposed human excrement and urine per mu, add 5-7.5 kg of potassium sulfate or potassium chloride, and apply with water; at the full flowering and early pod stage, use 0.2-0.5 kg of potassium dihydrogen phosphate per mu mixed with 50 kg of water for foliar spraying to prevent flower and pod drop and avoid affecting yield.

4. Timely sowing: Sowing too early will cause early flowering and affect yield, while delaying sowing will affect the next spring crops. Sow around 5 days before and after Frost's Descent, with a row spacing of 33 cm and a hole spacing of 12-18 cm, sowing 2-3 seeds per hole, at a sowing depth of 5-6 cm, with a sowing rate of 8-15 kg per mu. After sowing, cover with soil miscellaneous fertilizer, and if conditions permit, seed dressing with rhizobia can be carried out.

5. Strengthen field management: Mainly grasp five key techniques. First, if missing plants are found 7 days after sowing, dig up denser seedlings nearby and transplant them with soil, or reseed with pre-germinated seeds. Second, when the seedlings reach 5-6 true leaves, cultivate and earth up once in combination with topdressing. Third, at the full flowering stage, choose a sunny and windless morning, and use a sickle or hands to cut or pick off the top buds by 4-6 cm.

6. Topping and pruning, and disease control. Fava bean topping is done twice. The first topping is around the Winter Solstice, removing the growing point of the main stem to promote earlier branching and increase the number of effective branches; the second pruning is when 30-40% of plants begin to form the first pod, removing tender branches by 2-3 cm, which can increase the pod-setting rate by about 20%. The main diseases of fava beans include chocolate spot and rust. Pay attention to control.

What causes flower and pod drop in fava beans?

1. There are many causes of flower and pod drop in fava beans, and their relationships are very complex. But the main causes can be summarized in two aspects: first, it is determined by the physiological characteristics of fava bean itself, and is the result of different organs competing during growth and development until automatically reaching balance; second, it is caused by adverse environmental conditions and extensive cultivation management.

2. Fava bean has an indeterminate growth habit, and the stem tip (terminal bud) continuously carries out vegetative growth until the pods mature. In this process, reproductive growth and vegetative growth proceed simultaneously. During this period, the buds, flowers, and pods of the reproductive organs continuously differentiate and develop, while the roots, stems, leaves, and other vegetative organs still grow rapidly, and the stem tip always occupies the main position in the absorption and distribution of nutrients within the plant, resulting in a lack of nutrients for the lower flowers and pods. The plant can only ensure concentrated nutrient supply to the remaining flowers and pods by reducing the total number of flowers and pods. Therefore, the competitive effect of upper vegetative growth on lower reproductive growth is strong, limiting the seed-setting and development of most flowers and pods. Thus, timely topping can increase the pod-setting rate of fava beans and increase yield.

3. Among environmental factors, light, temperature, water, and fertilizer can all have extremely complex effects on fava bean flower and pod drop: excessive sowing density can cause plants to grow excessively due to poorer light conditions among branches, increasing the flower and pod drop rate. And some disastrous climates, such as low temperature, frost, drought, and continuous rainy days, can further lead to freezing damage and poor pollination, directly causing large numbers of flowers and pods to drop. In particular, if fava beans encounter insufficient or excessive water during the flowering and pod-setting period, their flowers and pods drop even more.