No abstract

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)

Preplant conditioning with solid carriers, termed matriconditioning, has proved effective in improving early emergence of vegetable seeds in laboratory studies. The objective of this study was to combine the advantages of matriconditioning with effective fungicide treatments to further improve emergence and yield in table beet (Beta vulgaris L. cv. Ruby Queen). Of the various carriers used, Micro‐Cel E (a synthetic calcium silicate) was found to be more effective than expanded vermiculite or Agro‐Lig (a Leonardite shale). The conditioning mixture consisted of 1 part seed to 0.2 part Micro‐Cel E to 1.15 part water (or fungicide suspension) by weight. Seeds were conditioned for 7 d at 15 °C. Although washing after conditioning improved the early emergence, air‐drying of conditioned seeds, with or without washing, was essential for obtaining maximum stand. A combined treatment of conditioning and metalaxyl [(N‐(2,6‐dimethylphenyl)‐N‐(methoxyacetyl) alanine methyl ester] + tolclofos‐methyl (O‐2,6‐dichloro‐4‐methylphenyl O,O‐dimethyl phosphorothioate) was more effective than the conditioning or fungicide seed treatment alone in improving stand and in reducing seedling mortality at 22 to 25 °C in soil infested with soilborne pathogen, Rhizoctonia solani Kuhn. In noninfested soil, conditioning with metalaxyl + thiram (tetramethylthiuram disulfide) was most effective. At 15 °C, conditioning in combination with metalaxyl + tolclofos‐methyl or metalaxyl + thiram induced earlier emergence and produced larger stands than did conditioning or fungicide treatment alone. In a filed trial planted on 1 May 1990, conditioning combined with metalaxyl + tolclofos‐methyl or metalaxyl + thiram produced a larger stand than did conditioning or fungicide treatment alone. In a field trial planted on 21 June 1990 and artificially infested with mycelial suspensions of R. solani and Pythium ultimum Trow, conditioning combined with metalaxyl + tolclofos‐methyl or metalaxyl + thiram reduced the early emergence time and increased the marketable root yield over that of conditioning or fungicide treatment alone. Root disease incidence was reduced maximally when conditioning was combined with metalaxyl + tolclofos‐methyl, to a lesser extent by fungicides alone, and none by conditioning alone.

et al.. Factors influencing ELISA evaluation of transmission of pea seed-borne mosaic virus in infected pea seed : seed-group size and seed decortication. Agronomie, EDP Sciences, 1987, 7 (4)

Respiration rates for germinating ‘Cougar’ and ‘Newport’ Kentucky bluegrass (Poa pratensis L.) seed produced in 1965, 1968, and 1969 (freshly harvested) increased rapidly for 2 to 4 days after imbibition in 0.2% KNO3 and in water, then slowly increased for the remainder of a 7–day period. Cougar seed treated with KNO3 had higher respiration rates than water‐treated seed; only slight increases were obtained with KNO3‐treated New port seed. Seed from 1965 and 1968 took up oxygen more rapidly than the 1969 seed. Respiration rates of 1– and 4–month‐old Newport seed decreased rapidly 3 to 4 days after imbibition.Germination tests of 1969 seed at 1 month after harvest after imbibition showed Newport seed to be more dormant than Cougar. KNO3 increased germination of 1–, 4– and 9–month‐old Newport seed but had no effect on Cougar seed.