Fruit Growing: Production Practices and Post-harvest Management—2nd Edition

The sweet oranges [C. sinensis (L.) Osbeck] produced in India are mainly consumed fresh as a table fruit and in the form of freshly extracted juice. Currently, a fraction of the fruit is processed into products like orange juice, concentrates, pulp, and other value-added products. Seedless varieties are preferred both by the consumers and by the processing industry; however, indigenously developed seedless sweet orange cultivars are not available. Citrus triploids are usually seedless due to their abnormal meiosis and embryo abortion. A research study was undertaken at CCRI Nagpur to develop triploid seedless plants of the local sweet orange cultivar Mosambi through endosperm culture in the shortest possible time by dovetailing various techniques. Various steps, viz., endosperm excision, standardization of media for callus initiation, somatic embryogenesis, shoot/root differentiation, mini-grafting, and validation of the triploid status through flow cytometry, chromosome counting, and other morphological parameters, were standardized, and seven confirmed triploid plants were finally produced. An evaluation of fruit quality parameters during the 2022 and 2023 fruiting seasons revealed that the fruits of the triploid sweet orange trees were commercially seedless. This is the first reported comprehensive study on the successful development of commercially seedless plants of the sweet orange cultivar Mosambi. The fruits of the triploid plants showed desirable fruit quality parameters in terms of their seed number (3 to 5.9/fruit), higher vitamin C content (34.4 to 42.66 mg), and lower limonene content (7.77 to 11.34 µg/mL). These triploid plants have the potential to gain recognition as a distinct variety. Full article

Strawberries are by far the most produced soft fruit (blueberries, raspberries, blackberries, and strawberries) worldwide, with China and the US being the two countries with the most production. In the US, strawberries reached a farm gate value of more than USD 3 billion in 2023 and are predominantly grown in the open field on an annual cycle in hilled-up soil beds using plastic mulch (plasticulture). This process relies on adequate pre-plant fertilizer application for plant establishment and fruit development. In North Carolina (US), it is current practice to apply pre-plant fertilizer containing 67 nitrogen (N) kg/ha; however, with increasing fertilizer costs and environmental concerns, questions remain as to whether or not pre-plant full-spectrum fertilizer rates can be reduced and substituted with organic low-N fertilizer sources, such as Polysulphate, without impacting yield or fruit quality. For this reason, field trials were established to evaluate the impact of pre-plant fertilizer rates on strawberry production (‘Camarosa’). Trials were conducted in the 2019–2020 and 2020–2021 seasons at two locations in North Carolina. The following N-rate pre-plant fertilizer treatments were applied: 80.1, 67.3, 54.1, 41.1, 33.6, 28.0, and 0 kg/ha. NO₃ and NH₄ content were frequently assessed in each replicate in the raised bed profile between planting and spring fertilizer application. Marketable and total strawberry yields were assessed over 6 weeks in the spring of 2020 and 2021. Our trial results showed that, especially in sandy soil, N rapidly declined under plastic within the first 8 weeks after pre-plant fertilizer application. However, no impact between pre-plant fertilizer rates and plant yield was observed. Treatments that contained Polysulphate and lower amounts of full-spectrum fertilizer showed significantly lower N concentrations in the soil while maintaining similar yields and fruit quality compared to grower-standard pre-plant fertilizer treatments. In summary, our results show that it is possible to reduce N content in pre-plant fertilizer by up to 50% compared to current recommendations without causing yield loss in short-day strawberry cultivars. Full article