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  • Author or Editor: A.S. Khan x
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Mango malformation is one of the major factors causing significant fruit loss in Pakistan. To investigate the role of malformation a long-term field experiment was established on 15 years old mango orchard. Malformation inflorescences were removed and counted in last week of April and fruit were harvested in July every year starting from 1989. Malformed inflorescence varied from plant to plant however, during 1990, 1991 and 1992 it decreased considerably over the control year (1989). The malformation was 77% during control year 1989, 57% during 1990, 57% during 1991 and 50% during 1992. Mango fruit yields were significantly decreased due to non-bearing malformed inflorescences. The mean yield decrease was 83 % during 1989 which relatively improved in later years and were 58% in 1990, 53% in 1991 and 54% in 1992.

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Present status and future prospects of cut rose (Rosa ×hybrida) flower production and postharvest management in Punjab, Pakistan, were investigated. Cut roses were the leading flower crop in the area under study, but production systems and practices were outdated and primitive, resulting in cut stems that were not acceptable in international markets. The majority of growers (65%) had only basic education (grade 10 or less) and 57% had small landholdings (<1 ha); therefore, they did not have modern production techniques and resources for high-quality cut rose production. Moreover, lack of production and postharvest facilities, ignorance of both public and private resources, and poor production and postharvest practices were prevalent. Growers' training regarding production and postharvest management would be required to lift the quality standards of this industry up to the international level. However, a positive trend was observed in cut rose businesses as more than half of growers (52%) entered into the business during last 5 years. In addition, 30% of growers were in business over 10 years, indicating that cut rose production can provide a sustained income for producers. This analysis of the cut rose industry in Punjab can serve as a model for other countries whose cut flowers industries are at a similar stage of development.

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Abstract

Increasing levels of N fertilizer (22, 45, 112 or 448 kg/ha) significantly increased protein and total fresh weight of the edible portion of lettuce, mustard, collards, cabbage, beets, corn, tomatoes, and peppers. Significant increases in protein and fresh weight of snap beans were observed only at the highest N level. The NO3 concentration in the edible part increased significantly in mustard and collards at all N levels; in lettuce and cabbage at the 2 higher N levels; and in snap beans at the highest N level only. The NO3 concentration was low in beets, corn and peppers. Tomato fruit contained no detectable NO3.

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A matriconditioning procedure based on the matric properties of Micro-Cel E and expanded vermiculite #5 has proved effective in improving seedling emergence in growth chambers. The major objectives of this study were to examine some physical characteristics of the carriers and their effectiveness as preplant conditioning media in improving stand establishment of vegetable seeds in field plantings. Carrier characteristics included no detectable solute or osmotic potential, low electrical conductivity (0.48-0.04 mmho/cm), high water-retaining capacity (450% to 600%), a pH range of 7.0 to 8.4, and ability to effectively control seed hydration (conditioning) at low matric potential. The seed: carrier: water ratio for seed conditioning ranged from 1:0.3-0.5:1-2 (by weight). In a field trial, conditioning of `Long Imperator' and `Nantes' carrot (Daucus carota var. sativus Hoffm.) seeds reduced the time to 10% of final emergence (T10) by 2.6 to 2.8 days and to 50% of final emergence (T50) by 2.1 to 3.0 days. Conditioning increased the final emergence percentage by 39% in 1-year-old `Long Imperator' compared to 150% in 4-year-old `Nantes' seeds. In another field trial, the effect of conditioning on stand establishment was evaluated in `Jackpot' tomato (Lycopersicon esculentum Mill.), `California Wonder' pepper (Capsicum annuum L.), and `BBL 47' snap bean (Phaseolus vulgaris) seeds. In tomato, conditioning reduced the T10 by 0.9 day, had no effect on T50, and increased the emergence percentage by 86%. In pepper, conditioning reduced the T10 and T50 by 1.5 days and increased the percentage emergence by 30%. In snap bean seeds, conditioning in Micro-Ccl E reduced the T10 and T50 by 0.8 day but adversely affected the percentage emergence. Further reductions in T10 and T50 (1.2 and 1.6 days, respectively) and restoration of percentage emergence to control level occurred upon addition of 0.001 mM GA3 during conditioning. Fungicides added to carrot, tomato, and pepper seeds, with or without conditioning, showed no additional improvements and, in a few cases, adversely affected emergence. A preplant conditioning in Micro-Ccl E, alone or in combination with GA3, smears to be a viable alternative to conditioning! seeds in liquid carriers. Chemical name used: gibberellic acid (GA3)

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Low doses of ultraviolet light (254nm UV–C) irradiation reduced postharvest rots of pome, stone and citrus fruits. Brown rot (Monilinia fructicola) of `Elberta' and `Loring' peaches was significantly reduced by UV–C. Alternaria rot (Alternaria spp.) and bitter rot (Colletotrichum spp.) the principal storage rots of `Golden Delicious apples showed significant reduction following UV–C treatment. Further application of UV–C was effective in controlling green mold rot (Penicillium digitatum) of `Dancy' Tangerines and `Marsh Seedless' grapefruits, stem end rot (Alternaria citri), as well as sour rot (Geotrichum candidum) of `Dancy' tangerines after irradiation.

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External and internal tomato irregular ripening (TIR) symptoms have been associated with the feeding of silverleaf whitefly (SLW), Bemisia argentifolii Bellows and Perring. Soil drench application of gibberellic acid (GA3) (100 ppm, Trial 1 and 2) and cycocel (CCC) (2000 ppm, Trial 1; 1000 ppm, Trial 2) were applied to dwarf cherry tomato (Lycopersicon esculentum) in the presence and absence of SLW to mimic the TIR disorder induced by the SLW. Application of GA3 induced external and internal TIR symptoms similar to the SLW-induced disorder in `Florida Petite'. There were essentially no TIR symptoms in fruit treated with CCC, an inhibitor of GA biosynthesis. In Trial 1, internal white tissue in GA3, SLW, and CCC treatments was expressed in 97%, 95%, and 4% of the total fruit, respectively. Incidence of external TIR symptom was highest (56%) in the GA3 plus SLW treatment. In Trial 2, GA3 application in the presence (83%) or absence (85%) of SLW resulted in the highest incidence of fruit with internal white tissue. External TIR symptoms induced by GA3 in the presence and absence of SLW were reduced with CCC application. These results suggest that the TIR disorder in tomato is induced by the SLW may be a GA3-regulated disorder.

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Silverleaf whitefly (SLW) (Bemisia argentifolii Bellows and Perring) feeding has been associated with development of tomato irregular ripening (TIR) symptoms. Four dwarf cultivars of cherry tomato (Lycopersicon esculentum L.) were infested with adult SLW to observe oviposition preference, tolerance and TIR symptom development. Oviposition preference was observed at low SLW population. Florida Petite was the most preferred and Micro-Tom the least preferred cultivar, with Florida Lanai and Florida Basket intermediate. Each cultivar exhibited TIR symptoms associated with feeding by the SLW. TIR fruit symptoms were expressed as longitudinal red streaks with yellow, green, pink or red blotches externally, and white, yellow or green tissue internally. External TIR symptoms ranged from 32% (Micro-Tom) to 82% (Florida Basket). However, external symptoms disappeared from 34% (Florida Lanai) to 56% (Micro-Tom) of the fruits during ripening. SLW infested plants had 82% (Florida Lanai) to 99% (Florida Basket) of fruits with internal white tissue regardless of external symptoms. Tomatoes with TIR symptoms rarely ripened to a mature red, and sometimes had empty locules, were smaller in size and were seedless.

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An apparatus was designed to deliver low-dose UV-C light to the surface of fruit on a processing line and tested for its control of postharvest decay. It consisted of a row of UV-C emitting lamps mounted on a frame above a conveyer belt that transported the fruit. The dosage of the UV-C light delivered to the fruit surface was regulated by varying the speed of the conveyor belt. Postharvest decay after 28 days storage of `Empire' apples was reduced 52% relative to the untreated checks when the fruit were conveyed at 6.2 m·min−1 (1.38 kJ·m−2 dose) under the UV-C apparatus. Factors affecting the practical application of UV-C irradiation of fruit for controlling postharvest decay are discussed.

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A study was conducted to investigate the morphological, physiobiochemical, enzymatic, and ionic differences among four cultivated citrus (Citrus sp.) rootstocks with different salt tolerances. Two salt-tolerant rootstocks [Rangpur lime (C. limonia) and Rubidoux (C. trifoliata)] and two salt-sensitive rootstocks [Carrizo citrange (Citrus sinensis × C. trifoliata) and Sanchton citrumello (C. trifoliata × C. paradisi)], were subjected to NaCl stress in greenhouse conditions. The 9-month-old plants were exposed to four different NaCl levels (0, 30, 60, or 90 mm) in sand culture for 3 months. Plant biomass (fresh weight, dry weight, root length, shoot length, and leaf thickness), physiological attributes [number of stomata, stomatal size, number of epidermal cells, photosynthesis rate, stomatal conductance (g S), water use efficiency, and transpiration rate]. and ion content (Na+, K+, Ca+2, Mg+2, and Cl) were adversely affected by salt stress, but salt-tolerant cultivars were comparatively less affected. Salt stress also enhanced antioxidant enzyme activity (superoxide dismutase, catalase, and peroxidase), particularly in salt-tolerant cultivars. The salt-sensitive cultivars accumulated the greatest content of Na+ and Cl in their leaves, whereas the salt-tolerant cultivars accumulated the greatest content of Na+ and Cl in their roots, an adaptation to combat the highly saline conditions. Overall, it was concluded that the salt tolerance of rootstocks is associated with a greater antioxidant enzyme activity and differing accumulation patterns of Na+, K+, Cl, Mg+2, and Ca+2 in leaves and roots; these can be considered potential indicators of a cultivar's sensitivity to salt stress.

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Flavorcrest, Camden. C. L. Wilson, Loring, Elberta, Summergold and Harken peach varieties were inoculated and naturally infected with Monilinia fructicolo after ultraviolet light irradiation (W-C 254nm) showed increased resistance to brown rot disease. Although dosages ranged from 0 to 20 KJ/m2. 7.5 KJ/m2 was considered the most effective for the peach varieties tested. Pretreatment of peaches by field spraying or dipping into a benomyl fungicide showed no significant differences between non-treated and UV-C treated peaches. However. a combination of a low dose of benomyl (.15g/L) 3 days following UV-C treatment showed a synergistic effect on brown rot reduction when compared to Peaches treated with UV-C alone and a greater reduction of brow rot than benomyl control.

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