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Paper mulch and black plastic mulch were compared with no mulch on tomatoes (Lycopersicon esculentum Mill. `Better Boy' and `San Marzano') for incidence of blossom-end rot (BER) in the field during 1988–90. Early season (late July to late August) harvest had more BER than in later pickings. Black plastic mulch significantly increased early season BER in `Better Boy' relative to paper or no mulch. Late-season BER in `San Marzano' was decreased with paper or black plastic mulch relative to no mulch.
Abstract
Thirteen seed treatments were compared to determine the optimal method to produce asparagus (Asparagus officinalis L. cv. Viking) seeds suitable for axenic culture. Treated seeds were examined for microbial contamination by culture on an agar medium and for percent germination by incubation on moistened paper. All treatments that included benomyl in acetone (2.5%, w/v) with 20% household bleach (0.1% sodium hypochlorite) were superior to the other treatments in eliminating bacterial and fungal contaminants without decreasing seed germination. Ethanol (70%) and hydrogen peroxide also decreased contamination levels, but ethanol decreased germination significantly. No evidence of internal contamination was detected when aseptic seeds were germinated and cultured on agar medium. Chemical names used: methyl(1-[(butylamino)carbonyl]-1H-benzimidazol-2-yl] carbamate (benomyl).
Abstract
Donor callus cells for protoplasts were initiated from mature plants of four selected crowns of asparagus (Asparagus officinalis L.) by placing spear slices on solidified Murashige and Skoog salts and vitamins medium (MS) with 3% sucrose + (in mg·liter−1): 1.0 NAA + 1.2 2,4-D + 0.9 BA or 1.0 kinetin + 2.5 2,4-D. Callus derived from these explants was further subcultured on the same medium. Optimum protoplast yields were enzymatically obtained from such calluses 10 to 20 days after subculture. Of the isolated protoplasts 65% to 75% were viable, and when plated in modified Kao and Michayluk medium at 5 × 104 or 105/ml densities, had 6.5% and 7.3% plating efficiencies, respectively. Protoplast isolations had 0.81% to 1.4% cells present that were not observed subsequently to undergo division. Only the cells of protoplasts of ‘Jersey Giant crown No. 8’ divided during 8 weeks to form microcalluses. After transfer and culture for an additional 4 to 5 weeks on solidified MS + (in mg·liter−1): 0.1 NAA + 1.0 kinetin, shoots regenerated at 28% efficiency. Shoots were rooted at 50% efficiency on solidified MS + (in mg·liter−1): 0.3 NAA + 0.7 kinetin + 2.1 ancymidol + 4% sucrose. The rooted plants were readily transferred to the greenhouse. Chemical names used: 1-naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), N-(phenylmethyl)-1H-purin-6-amine (BA), N-(2-furanylmethyl)-1H-purin-6-amine (kinetin), α-cyclopropyl-α-(4-methoxy-phenyl)-5-pyrimidine methanol (ancymidol).
Can regulated deficit irrigation in an ebb and flow system alleviate the effects of salinity stress on poinsettia? Two cultivars of poinsettia (Euphorbia pulcherrima Willd ex Klotzsch) were grown under partial- or full-saturation irrigation using a standard fertilizer solution, with or without the addition of 0.5 g·L−1 NaCl. The volumetric water content of the medium averaged 0.25 and 0.33 L·L−1 before irrigation, and 0.5 and 0.67 L·L−1 following irrigation, for partial- or full-saturation regimes, respectively. Plants had lower fresh weight with partial than full saturation. Sodium concentrations in bract, leaf, and stem tissues were higher (P ≤ 0.05) in plants exposed to salinity, and these plants accumulated less K in stems and less P in bracts. Eight cultivars were grown in a second study with or without salinity of 1.2 g·L−1 NaCl under drip or ebb and flow watering. Cultivar and watering had effects on plant fresh weight, but salinity did not. Of the cultivars tested, ‘DaVinci’, ‘Premium Picasso’, and ‘Prestige Red’ had the highest sodium in bracts under salinity with drip irrigation, whereas ‘Snowcap’ had the least. ‘Ruby Frost’ had the most sodium in stems, whereas ‘Snowcap’ had the least. For all cultivars, added salinity resulted in lower K in leaves and stem. Snowcap was the cultivar with the least sodium in stems and bracts under saline irrigation, with either drip or ebb and flow. Our research demonstrates that regulated deficit irrigation resulting in partial saturation of the growing medium is an effective water management option, when control of plant height and overall crop growth are desirable, and it limits the accumulation of sodium when raw water contains elevated salinity.