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28 Sep 2021
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Effect of Various Irrigation Rates on Growth and Root Development of Young Citrus Trees in High-Density Planting

Citrus yields have declined by almost 56% since Huanglongbing (HLB) was first found in Florida (2005). That reduction forced citrus growers to replant trees at much higher densities to counter-balance tree loss. The current project aims to determine how much water is required to grow citrus trees at higher planting densities without reducing their productivity. The study was initiated in November 2017 on eight-month-old sweet orange (Citrus sinensis) trees grafted on the ‘US-897′ (Cleopatra mandarin × Flying Dragon trifoliate orange) citrus rootstock planted in the University of Florida, Southwest Florida Research and Education Center (SWFREC) demonstration grove, in Immokalee, FL (lat. 26.42° N, long. 81.42° W). The soil in the grove is Immokalee fine sand (Sandy, siliceous, hyperthermic Arenic Alaquods). The demonstration grove included three densities on two rows of beds (447, 598, and 745 trees per ha) replicated four times each and three densities of three rows of beds (512, 717, 897 trees per ha) replicated six times. Each density treatment was irrigated at one of two irrigation rates (62% or 100%) during the first 15 months (2017–2019) then adjusted (2019–2020) to represent 26.5, 40.5, 53, and 81% based on recommended young citrus trees evapotranspiration (ETc).

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28 Sep 2021
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South African seedless lemons to China

Seedless lemons have already found a sweet spot in various global markets at premium retailers where the seedlessness of the product addresses culinary frustrations experienced by chefs, home-cooks, health enthusiasts, mixologists and lovers of all things lemony. The seedless lemon has been described as the holy grail of the industry.

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28 Sep 2021
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Effect of Different Day Temperatures on Flowering and Fruiting in Tosa Buntan Pummelo (Citrus grandis (L.) Osbeck)

The effect of different day temperatures during winter and spring seasons on the flowering and fruiting of 3-year-old potted Tosa Buntan pummelo (Citrus grandis (L.) Osbeck) trees grafted on trifoliate orange (Poncirus trifoliata Raf.) rootstock was investigated. The experiment was conducted in growth chambers with setting day temperatures of 15℃, 20℃, 25℃, 30℃ and 35℃, while night temperature in each chamber was set at a constant 10℃. The temperature treatments were started on December 18, 1989 and terminated on May 1, 1990, except for the 15℃ day temperature treatment which lasted until June 11, 1990. After the temperature treatments in the growth chambers, all trees were grown in the same way in the field condition until harvesting time of November 15, 1990. The lowest day temperature treatment of 15℃ needed considerably more days to flower bud initiation and greatly inhibited flower bud development, thus all flower buds in this regime dropped before and after their opening.

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28 Sep 2021
Sheet Mulching
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Sheet-mulching Cultivation Promotes the Number of Floral Buds via Upregulation of Citrus Flowering Locus T Expression in Two Citrus Cultivars,‘Haraguchi-wase’ and ‘Harehime’

Sheet-mulching cultivation during the fruit developmental stage is often carried out to produce high-quality Satsuma mandarin (Citrus unshiu Marc.) and ‘Harehime’ ((‘Kiyomi’ × ‘Osceola’) × ‘Miyagawa-wase’) fruits because they show high Brix% by exposure to drought stress conditions. In this study, we investigated the effect of drought stress on the number of floral buds in ‘Haraguchi-wase’ Satsuma mandarins and ‘Harehime’. To clarify the relationship between drought stress and the number of floral buds, we applied four different drying treatments to the fruit trees, (i) first-half drying (drying treatment during the first-half of the fruit development stage), (ii) second-half drying (drying treatment during the second-half of the fruit development stage), (iii) all-drying (drying during the full fruit development stage), and (iv) well-watered (non-drought stress during the fruit development stage). The drying treatment was applied to the fruits at ψ max −0.7 to −1.2 MPa at an intensity comparable to proper drought stress for high-quality fruit production according to our previous studies.

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24 Aug 2021
Yield
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The influence of nitrogen concentration and ammonium/nitrate ratio on N-uptake, mineral composition and yield of citrus

In  short-term   water  culture  experiments  with  different  15N  labeled  ammonium  or  nitrate  concen trations,  citrus seedlings absorbed  NH; at  a higher  rate  than  No;. Maximum NO; uptake  by the whole plant  occurred  at 120 mg L – 1  NO;-N, whereas NH; absorption  was saturated  at 240 mg L –  1 NH;-N. 15NH; accumulated in roots and to a lesser degree in both leaves and stems. However,  15NO; was mostly partitioned  between leaves and roots.

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24 Aug 2021
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Relationship between chloride and nitrate and its effect on growth and mineral composition of avocado and citrus plants

Two rootstocks of avocado (Persea americana Mill.), the salt-tolerant ‘Degania-113’ and the salt-sensitive ‘Smith’, and two rootstocks of citrus, the salt-tolerant ‘Cleopatra’ mandarin (Citrus reshni Hort. ex Tan) and the salt-sensitive ‘Troyer’ citrange (Poncirus trifoliata x Citrus sinensis [L.] Osbeck), were grown in a sandy soil and irrigated daily with nutrient solutions containing various chloride concentrations. Increasing the concentration of chloride resulted in elevated chloride levels in all avocado plant parts, and toxic symptoms that were more pronounced in the ‘Smith’ than in the ‘Degania-113’ avocado rootstock. When leaves of both rootstocks had accumulated similar chloride levels and showed scorching damage, the leaves of ‘Degania-113’ abscised, while those of ‘Smith’ did not. High chloride reduced the total dry matter yield of the root more than that of the shoot, decreasing the “root: shoot” dry weight ratio in both rootstocks. Addition of nitrate to the irrigation water reduced chloride accumulation in the plant and alleviated its adverse effects. Accumulation of nitrogen in the plant exceeded that of chloride in all cases.

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24 Aug 2021
Soil
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A Review of the Use of the Basic Cation Saturation Ratio and the “Ideal” Soil

The use of “balanced” Ca, Mg, and K ratios, as prescribed by the basic cation saturation ratio (BCSR) concept, is still used by some private soil-testing laboratories for the interpretation of soil analytical data. This review examines the suitability of the BCSR concept as a method for the interpretation of soil analytical data. According to the BCSR concept, maximum plant growth will be achieved only when the soil’s exchangeable Ca, Mg, and K concentrations are approximately 65% Ca, 10% Mg, and 5% K (termed the ideal soil). This “ideal soil” was originally proposed by Firman Bear and coworkers in New Jersey during the 1940s as a method of reducing luxury K uptake by alfalfa (Medicago sativa L.).

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24 Aug 2021
Horticultural planning
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Horticultural practices

Grove management starts with planning of the planting site, and by comprehending every operation until harvesting time in order to achieve the best marketable fruit yield and quality. It includes horticultural practices such as grove establishment, irrigation, nutrition, canopy management, and grove protection. Importantly, fruit quality starts in the grove. In this chapter we are focusing on grove planning with special focus on tree spacing, canopy management, and tree size control, and crop load management from a horticultural point of view.

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