Expansion of green-white and red fruit in control (watered) and water-stressed greenhouse-grown strawberry (Fragaria x ananassa Duch. 'Brighton') plants was monitored with pressure transducers. Expansion of green-white fruit in control plants was rapid, showing little diurnal variation; whereas in water-stressed plants, fruit expansion occurred only during dark periods and shrinkage during the day. Red fruit were mature and failed to show net expansion. The apoplastic water potential (psi aw), measured with in situ psychrometers in control plants was always higher in leaves than in green-white fruit. In stressed plants, psi aw of leaves was higher than that of green-white fruit only in the dark, corresponding to the period when these fruit expanded. To determine the ability of fruit to osmotically adjust, fruit were removed from control and water-stressed plants, and hydrated for 12 hours; then, solute potential at full turgor (psi s 100) was measured. Water-stressed green-white fruit showed osmotic adjustment with a psi s 100 that was 0.28 MPa lower than that of control fruit. Mature leaves of water-stressed plants showed a similar level of osmotic adjustment, whereas water stress did not have a significant effect on the psi s 100 of red fruit. Fruit also were severed to permit rapid dehydration, and fruit solute potential (psi s) was plotted against relative water content [RWC = (fresh mass - dry mass divided by fully turgid mass - dry mass) x 100]. Water-stressed, green-white fruit had a lower psi s for a given RWC than control fruit, further confirming the occurrence of osmotic adjustment in the stressed fruit tissue. The lack of a linear relationship between turgor pressure and RWC prevented the calculation of cell elasticity or volumetric elastic modulus. Osmotic adjustment resulted in about a 2.5-fold increase in glucose and sucrose levels in water-stressed green-white fruit. Although green-white fruit on water-stressed plants showed osmotic adjustment, it was not sufficient to maintain fruit expansion during the day.

'Marsh' grapefruit (Citrus paradisi Macf.) produced in Florida must be certified for security against unwanted pests before entry into some domestic and export markets. Application of heat by hot water (HW) has been shown to cause severe injury to grapefruit; however, direct comparisons between forced vapor heat (VH) and HW have been lacking. Grapefruit preharvest-treated with gibberellic acid (GA) or not treated, were postharvest treated with VH or HW such that the surfaces of fruit were exposed to the same rate of temperature increases and treatment duration. Condition and quality attributes were then compared with ambient air (AA) and ambient water (AW) control after storage. After 4 weeks' storage at 10 degrees C plus 1 week at 20 degrees C, scald affected 5% of HW and 20% of VH-treated fruit. No scald developed on control fruit. At the end of storage, mass loss for HW and VH fruit was approximately 5%. HW-treated fruit had a 5-fold higher incidence of aging than VH fruit; however, control fruit showed significantly more aging than all heat-treated fruit. Gibberellic acid (GA) and the heat treatments reduced decay relative to the control. GA-treated fruit remained greener during storage than control fruit. These findings indicate that VH and HW treatments at the temperatures and durations to control the Caribbean fruit fly (Anastrepha suspensa, Loew) will likely cause peel injury to 'Marsh' grapefruit produced in Florida, regardless of treatment with GA.

In the last few years, genes coding for several enzymes (copalyl diphosphate synthase, ent-kaurene synthase, GA 7-oxidase, GA 20-oxidase and GA 3 beta-hydroxylase) in the gibberellin biosynthesis pathway have been cloned and characterized. This review concentrates on these recent advances, making emphasis on the regulation of fruit-set and development by gibberellins. | Conselleria Agr Pesca & Alimentac Generalitat Valenciana; Min Flemish Commun, Adm Agr & Horticulture Belgium | Peer reviewed

The effect of different concentrations of polyoxin and culture supernatant of Bacillus subtilis was tested against rot fungi on longan cv. Shixia fruit. Both have good control of rot caused by Botryodiplodia. Control of the fungus was better at the higher concentrations of the two treatments. Control of fruit decay, treated with the culture supernatant of Bacillus subtilis, polyoxin, or a combination of both, was good up to 30 days at 5 d̀C after treatment, but markedly decreased when fruit was stored for a longer time. The combination was better than either treatment alone, and resulted in 96.3% good fruit in cold storage after 30 days compared with only 66.3% for the control.