Demographics and household characteristics of respondents
As an economic activity, navy bean production is carried out by people of different ages in the villages sampled (Table 3). The age group, 41 – 50 years had the highest respondents and accounted for 28 % of the surveyed population (Table 3). There were also respondents above 70 years that were involved in navy bean production in all the areas surveyed.
Navy bean production, farming systems and important crops grown
Rainfall is unimodal and seasons are classified accordingly. Summer season is characterized by rains from November to March/April and high temperatures, followed by winter season, which is dry and associated with low temperatures (April to July). The formal survey revealed that Maize (Zea mays L.), navy beans, onions (Allium cepa L.), wheat (Triticum aestivum L.), tomatoes (Solanum lycopersicum L.), velvet beans (Mucuna pruriens L.), sorghum (Sorghum bicolor L.), Lablab (Lablab purpureus L.), and okra (Abelmoschus esculentus L.) were the major food crops grown in the study areas (Table 4). Sunflower (Helianthus annuus L.), groundnut (Arachis hypogaea L.), and bambara groundnut (Vigna subterranea L.) were ranked as minor crops across all the villages. Most of the navy bean was grown during the dry winter season under irrigation using the scarce irrigation water resources alongside horticultural crops (onions and tomatoes) and wheat. Navy bean summer production was constrained by high temperatures and drought, even though some of the farmers grew navy beans in small plots for household consumption. The rest of the crops were mainly grown in summer. The food crops were ranked by both male and female farmers based on cultivation area, cash income and food security as outlined in the sections below.
Crops based on cultivation area
Maize (81 %), navy bean (44.4 %), tomatoes (23.1 %), onions (16.3 %) and sorghum (14.1 %) were the major crops grown by both male and female farmers in the study areas in terms of cultivation area (Table 4). In each of the villages, maize was ranked first by more than 50 % of both male and female respondents. In Nenhowe and Tonhorai villages, navy bean ranked second with 44.4 % (males) and 29.6 % (females), 39.2 % (males), and 70.4 % (females) of respondents, respectively, while at Maunganidze village, it was ranked equally with maize in importance (65.2 %) among women farmers.
Crops based on cash income
Based on cash income, and in order of ranking by the male and female farmers, navy bean, maize, tomatoes, onions, and wheat (Triticum aestivum L.) were the major crops grown in the study areas (Table 4). In all the four villages, navy bean was ranked first by 49-65.2 % of the respondents, while in Maunganidze, Nenhowe and Tonhorai villages, it ranked second after maize among female farmers only. In contrary to women, male farmers in all the villages ranked navy bean as the most important cash crop ahead of maize, tomatoes, onions and wheat. The ranking for the other crops is shown in Table 4.
Crops based on food security
Regarding food security, maize (100 % of respondents), navy beans (17.5 %), sorghum (13.7 %) and wheat (8.1 %) were the major crops as indicated by both men and women (Table 4). In Gudyanga and Nenhowe villages, navy bean was ranked second by 8.0 % and 14.8 % of the male respondents, respectively, while in Maunganidze village among men, it occupied the third (8.0 %) place after sorghum and wheat, which were ranked equally (16.4 %). Sorghum (31.2 %) occupied the second place at Tonhorai village among women, while navy bean occupied the same place at Nenhowe (29.6 %) and Gudyanga villages among women.
Land size and navy bean production yield
Sole cropping was the predominant (100 %) cropping system in all the surveyed villages (Table 5). Farmers cultivated navy bean farming on small land holdings (mean = 0.27 ha). The average land size allocated to navy bean production was not significantly different among the villages ranging from 0.23 (Gudyanga) to 0.32 ha (Nenhowe) (Table 5). On average the total land size per household was 0.75 ha, with the smallest being 0.69 ha (Gudyanga) and the largest being 0.77 ha (Tonhorai). The average grain yield of navy bean varied significantly (p < 0.05) from village to village with Gudyanga having the highest yields (Table 5). Focus group discussions reported average grain yields of 2.45, 2.76, 2.19 and 2.42 t ha−1 in Tonhorai, Gudyanga, Nenhowe and Maunganidze villages, respectively.
Navy bean production constraints
Navy bean production was hampered by many constraints. Challenges ranged from biotic, abiotic and socio-economic constraints (Table 6). The perception of the constraints affecting navy bean production in the study locations was not different within and across villages as well as between men and women within the villages. The ranking of the constraints among both male and female farmers across all the locations did not differ much. Drought stress, heat stress, load shedding/power outages, susceptibility to pod shattering, poor soil fertility, insect pests, seed availability and diseases were the main constraints of navy bean production across all the villages according to both male and female farmers.
The most challenging insect pests across all the locations were the black bean aphid, bean stem maggot and harvester termites [Hodotermes mossambicus (Hagen) (Isoptera: Hodotermitidae)]. Diseases mainly comprised of bean rust (Uromyces appendiculatus), angular leaf spot (Pseudocercospora griseola), and common bacterial blight (Xanthomonas axonopodis pv. phaseoli). Drought stress was the second most challenging constraint in Nenhowe (68 %) and Tonhorai (64 %) villages among male farmers, while heat stress ranked the same at Gudyanga (60 %), Maunganidze (64 %), Nenhowe (48 %) and Tonhorai (60 %) villages among female farmers. Farmers reported that drought stress mainly occurred during the reproductive stage of growth and heat stress was common in the late planted crop for a short period of time. The other major constraints reported by both male and female farmers were lack of access to transport, low yielding cultivars, and shortage of labour.
Management strategies for moisture and heat stress
The strategies used by farmers to alleviate the effects of moisture stress are summarized in Table 7. A total of 40, 38, 33 and 43 % of farmers in Gudyanga, Maunganidze, Nenhowe and Tonhorai villages, respectively, did not use any strategy to manage/control moisture stress. However, soil mulching, reduced acreage, use of ridges, cultivating to retain more soil moisture, adjusting planting dates, and watering of plants at night are the strategies that were used by the other farmers to alleviate the effects of moisture stress. Soil mulching was the most widely used method of managing moisture stress at Gudyanga (29 % of respondents), Maunganidze (16 %) and Tonhorai (14 %). During FGDs, farmers in all the four villages highlighted the importance of soil mulching in suppressing and reducing weed infestation and fungal disease pressure. At Nenhowe village, the most common method was the use of ridges (22 %) followed by cultivating to retain more soil moisture. Overall (18 %), soil mulching was the most common method of managing moisture stress as reported by 29, 16, 14 and 6 % of farmers interviewed at Gudyanga, Maunganidze, Tonhorai and Nenhowe villages, respectively. Ridges (12 %) were the second most widely used strategy, followed by reducing acreage (11 %) and cultivating to retain more soil moisture (11 %). Less common strategies of managing moisture stress included adjusting planting dates (3 %) and watering of plants at night (6 %).
The strategies used by farmers to alleviate the effects of heat stress are summarized in Table. 7. Irrigating at night (reported by 32 % of respondents), adjusting planting dates (29 %), and mulching (20 %) are the methods that were used by farmers to alleviate the effects of heat stress. However, overall, 19 % of the farmers across all the villages did not use any heat stress management/control strategy. A total of 56, 38, 22 and 18 % of farmers at Nenhowe, Tonhorai, Maunganidze and Gudyanga villages, respectively, confirmed using the strategy of adjusting planting dates to alleviate the effects of heat stress. At Gudyanga and Maunganidze, the most commonly used methods were mulching (33 %) and irrigating at night (49 %) respectively. Overall (32 %), irrigating at night was the most common method of alleviating the effects of heat stress as reported by 49, 25, 24 and 21 % of farmers interviewed at Maunganidze, Nenhowe, Gudyanga and Tonhorai villages, respectively.
Navy bean marketing constraints
Navy bean production was hampered by many constraints among which are: lack of diversity in terms of buyers/off-takers, non-payment for produce in hard currency, delayed payment by contractor, low grain producer price, and inflation eroding the value of the produce (Table 8). Non-payment for produce in hard currency was the top most challenging constraint among both male and female farmers at Gudyanga, Nenhowe and Tonhorai, while lack of diversity in terms of buyers/off-takers (92 % of male respondents) and low grain producer price (100 % of female respondents) were ranked the same at Maunganidze. The other major challenging constraints among both male and female farmers were lack of transport to ferry produce, non-transparent grading, expensive packaging material and breach of contract by contractor.
Farmer preferred traits for improvement during navy bean breeding
Across all the locations, farmers concurred that there was need for improvement of certain traits in the current cultivars. The farmer-preferred traits for improvement are summarized in Table 9. Tolerance to heat (72 % of the respondents), and drought (72 %), resistance to diseases (72 %), and insect pests (71 %), maturity period (71 %), grain yield (71 %), pod size (69 %), grain size (68 %), and resistance to pod shattering (68 %) were identified as the most important traits that needed enhancement by both male and female farmers across all the locations. Canning quality (26 %) and nutritional value (iron and zinc) (28 %) were the least important traits for improvement among both male and female farmers across all the villages. Generally, no gender differences were observed for farmers’ trait preferences across the villages.
Sources of seed supply and cultivar preferences by farmers
The major source of navy bean seed was the canning company (94 %) as a business venture (Fig. 1). For household consumption especially during summer season, the neighbouring farmers, research institutions, and seed companies were a critical seed source. Most of the respondents were not well informed of the existence of improved navy bean cultivars such as Protea and Teabus. Zimbabwe White Bean formerly called Michigan pea bean was the most widely grown navy bean cultivar among both men and women farmers at Nenhowe (70 % of respondents), Gudyanga (85 %), Tonhorai (82 %), and Maunganidze (90 %) (Table 10). The second most widely cultivated navy bean cultivar was Teabus (Nenhowe – 25 %, Gudyanga – 11 %, Tonhorai – 18 %, and Maunganidze – 10 %).
Farmers’ desirable and undesirable characteristics of the navy bean cultivars
About 45 % and 13 % of the farmers across all the locations desired high grain yield and disease tolerance of the Zimbabwe White Bean cultivar, respectively (Fig. 2). However, more than 15 % of the farmers indicated they did not like any attribute of the Zimbabwe White Bean and Teabus cultivars, but they were the only available cultivars that were offered by the contractor/canning company. Even though Caledon was not widely grown, 2 % of the farmers who cultivated the cultivar liked the high grain yield potential of the cultivar.
The undesirable characteristics of the navy bean cultivars grown by farmers across the four villages are presented in Fig 3. Results indicated that susceptibility to pod shattering (3 % of respondents), susceptibility to insect pests (45 %), susceptibility to diseases (27 %), susceptibility to heat stress (8 %), small seed size (2 %), low grain yield potential (15 %), and susceptibility to drought stress (10 %) were some of the undesirable traits of Zimbabwe White Bean cultivar. The cultivar Caledon had only one undesirable characteristic across all the locations which was susceptibility to insect pests (2 %), mainly the black bean aphid. With regards to Teabus, some of the undesirable characteristics across the four villages were; susceptibility to pod shattering (5 %), susceptibility to insect pests (33 %), susceptibility to diseases (24 %), susceptibility to heat stress (7 %), small seed size (8 %), low grain yield potential (19 %), short plant height (5 %), small pod size (3 %), and susceptibility to drought stress (8 %).