1. Introduction: The functioning of natural and agricultural ecosystems is based on biodiversity, and the reduction of biodiversity is considered a serious threat to the sustainability of agricultural ecosystems and world food security. Intensification and improper use of external inputs have led to ecosystems with less diversity and greater vulnerability. Afghanistan has an agricultural-based economy, and the food security of people is mostly dependent on national agricultural production. However, in recent years, food production in the country has been threatened due to complicated political conditions. It is well documented that proper use of biodiversity could enhance crop production in low-input systems. In Afghanistan, all vegetables and summer crops are known as “vegetables”; however, so far, no published information is available on this important species. This study was conducted to evaluate the vegetables and summer crops in the agroecosystems of Afghanistan.
2. Materials and Methods: To carry out this research, a countrywide dataset was collected. The required data were extracted from questionnaires collected in 388 counties across 34 provinces. For this purpose, in the growing season of 2019 -2020, all provinces and at least 10% of the counties located in each province were selected and evaluated based on the cultivated area of vegetables and summer crop species across the provinces. The national registered information and the data available in the agricultural management centers of the provinces were also used. The existing production systems were differentiated using cluster analysis. Shannon diversity index, Simpson diversity index, and species evenness index were also calculated. The common crop rotations in different provinces were extracted from the questionnaires and included in the relevant table.
3. Results and Discussion: The cultivated vegetables and summer crops in the country are divided into two groups: major vegetables, including Potato (Solanum tuberosum L.), Tomato (Solanum Lycopersicon), Onion (Allium cepa L.), Melon (Cucumis melo L), and Watermelon (Citrullus vulgaris L.), and minor vegetables. Watermelon, Melon, Potato, Tomato, and Onion constitute (2.62 %, 2.16 %, 1.56 %, 0.5%, and 0.5 %) of the country's total cultivated area, respectively. The cluster analysis of the cultivated area of various vegetables and summer crops showed the existence of 6 clusters based on the cultivated area and the vegetable production system, number of main vegetables and summer crops cultivated in each province. After Nimroz province (42334 ha), Jawzjan, Farah, and Badghis provinces have the largest cultivated area of five main vegetables and summer crops (27843 ha, 26858 ha, and 23376 ha, respectively). Shannon and Simpson diversity indices were low in most provinces and generally in the vegetable production systems of Afghanistan. On average, the highest value of the Shannon diversity index of vegetables and summer crops was 1.52 (in Baghlan), and the lowest value was 0.05 (in Bamyan). The Simpson's index, with a slight change of maximum of 0.76 and a minimum of 0.02, was estimated for vegetable species. The Evenness index indicated the wide spread of monoculture and low genetic diversity in the vegetable production system in the country. The genetic diversity of vegetable cultivation in Afghanistan was also low, but in the meantime, melon with 76 native genotypes in Faryab, Jawzjan, Balkh, Sarpol, Badghis, and Herat provinces has the highest genetic diversity, and potato with 9 genotypes ranked second. The study showed that the provinces of Afghanistan are very similar in terms of the proportion of land allocated to vegetables. Vegetables appeared in short rotations with cereals, usually with similar sequences in all provinces.
4. Conclusion: The vegetable production systems in Afghanistan suffer from poor diversity at the genetic and species levels. While 31 species of vegetables and summer crops are cultivated by farmers, only 5 species (Watermelon, Melon, Potato, Tomato, and Onion) are widely distributed throughout the country, and three provinces of Bamyan, Nimroz, and Maidan Wardak have the highest percentage of vegetables and summer crops cultivation. Genetic diversity of vegetables in Afghanistan is low, but melons with 76 local genotypes have the highest genetic diversity. In general, the most important solution for poor farmers with limited access to inputs is to increase the species and genetic diversity in order to improve and stabilize production without needing to increase the consumption of external inputs.