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`Moss Curled' seeds of parsley (Petroselinum crispum L.) were primed osmotically in polyethylene glycol or matrically in fine, exfoliated vermiculite at -0.5 MPa for 4 or 7 days at 20 or 30 °C with 0 or 1 mm GA3. All priming treatments stimulated and hastened germination. Matric priming resulted in greater germination (89%) than osmotic priming (83%) when seeds were primed for 7 days at 30 °C, but priming agent had no effect on germination percentage following priming at 20 °C or for 4 days. In seeds primed for 4 days at 20 or 30 °C, matric priming hastened germination more than did osmotic priming. Germination was generally less synchronous with matric than with osmotic priming. Increasing priming time from 4 to 7 days increased the rate of germination, but increased germination synchrony only when seeds were primed a t 20 °C. Inclusion of 1 mm GA3 during priming had little or no effect on germination. All matric priming treatments (other than 4-day priming) were repeated to assess seedling emergence in a greenhouse (25°C day/22 °C night). Priming increased the percentage, rate and synchrony of emergence, and increased hypocotyl length at 3 weeks after planting. Priming at 30 °C with 1 mm GA3 resulted in the greatest emergence percentage, hypocotyl length, and shoot dry weight. We conclude that matric priming is a satisfactory alternative to osmotic priming of parsley seeds. Chemical name used: gibberellic acid (GA3).

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`Moss Curled' seeds of parsley (Petroselinum crispum L.) were primed osmotically in polyethylene glycol or matrically in fine, exfoliated vermiculite at –0.5 MPa for 4 or 7 days at 20 or 30 °C with 0 or 1 mm GA3. All priming treatments stimulated and hastened germination. Matric priming resulted in greater germination (89%) than osmotic priming (83%) when seeds were primed for 7 days at 30 °C, but priming agent had no effect on germination percentage following priming at 20 °C or for 4 days. In seeds primed for 4 days at 20 or 30 °C, matric priming hastened germination more than did osmotic priming. Germination was generally less synchronous with matric than with osmotic priming. Increasing priming time from 4 to 7 days increased the rate of germination, but increased germination synchrony only when seeds were primed at 20 °C. Inclusion of 1 mm GA3 during priming had little or no effect on germination. All matric priming treatments (other than 4-day priming) were repeated to assess seedling emergence in a greenhouse (25°C day/22 °C night). Priming increased the percentage, rate and synchrony of emergence, and increased hypocotyl length at 3 weeks after planting. Priming at 30 °C with 1 mm GA3 resulted in the greatest emergence percentage, hypocotyl length, and shoot dry weight. We conclude that matric priming is a satisfactory alternative to osmotic priming of parsley seeds. Chemical name used: gibberellic acid (GA3).

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Abstract

Studies with adenylate kinase (IUBN 2.7.4.3) activity in soluble and mitochondrial fractions from sweet lemon, Citrus limettioides, Tanaka, and sour lemon Citrus limon, L., were conducted. These species differ greatly in organic acid contents of fruits. These studies involved distribution, pH optimum, Mg++ requirement, inhibition of NaF, and equilibrium constant determination. The total adenylate kinase activity for the soluble and mitochondrial fractions was about 34% higher in extracts from sour lemons than in those from sweet lemons. The enzyme preparations from sweet lemons were more sensitive to inhibition by NaF than those from sour lemon. In both lemons, mitochondrial adenylate kinase activity was only 6–8% of the total adenylate kinase activity. Enzymatic breakdown of AMP to adenosine was higher in the soluble fraction than in the mitochondrial fraction.

Open Access

Abstract

Metalaxyl, etridiazole, and captan were incorporated at 0, 50, 450, and 850 mg active ingredient per liter of magnesium silicate (Laponite 445) gel to ascertain fungicide efficacy in controlling damping-off [Pythium aphanidermatum (Edson) Fitzp.] in fluid-drilled ‘Heinz 1350’ tomato (Lycopersicon esculentum Mill.). Metalaxyl and etridiazole at 50 and 450 mg a.i./liter, respectively, gave percentage emergence values in infested growth media equal to those in control media. Captan at 850 mg a.i./liter gave lower percentage emergence values in Pythium-infested media than in control media. Thus, damping-off control efficacy was in the order metalaxyl > etridiazole > captan. Seedling growth reflected fungicide efficacy in controlling Pythium, since plant fresh weight and infection index values were inversely related. Fungicides incorporated in gel were nonphy to toxic.

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Abstract

One-year-old seedlings of rough lemon (Citrus jambhiri Lush.) and trifoliate orange (Poncirus trifoliata (L.) Raf.) grown in potted soil showed little adverse effect from 16-consecutive-weekly applications of up to 300 ppm Fe as FeEDTA, FeDTPA, or FeEDDHA. The iron contents of leaves were increased consistently by the increasing Fe levels, but the increases were modest and generally were not a factor which influenced yields except in overcoming Fe deficiency in calcareous soil. The only major adverse effect of the high chelate levels was the tendency of FeEDDHA to induce Mn deficiency with limed soil.

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One-year-old crowns of `Jersey Giant' asparagus (Asparagus officinalis L.) were forced into spear production at 28C in darkness. Total spear fresh weight and number per square meter responded quadratically to the percentage of sand incorporated in Pro-Mix BX (PMX) peat-lite medium, with maximum yields at 25% to 75% (by volume) PMX. In a second study conducted at 22 and 28C, total spear fresh weight and number per square meter for 96 days of harvest were similar when grown in weathered, spent mushroom compost (SMC) or 1 PMX: 1 sand (v/v), but were lower than those grown in PMX. The lower temperature caused heavier individual spears, while the higher temperature stimulated earlier spear production. During the first month of harvest at 22C, the total number and fresh weight of spears in SMC were 11% and 17% less, respectively, than in PMX. SMC may be a low-cost forcing substrate for white asparagus.

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Abstract

Starting from daylength (DL) × temperature (T) environments combining short or intermediate DL with low or intermediate T, days to first flower (FF) of beans was progressively decreased as the duration of T was extended and/or as T was raised to intermediate levels. This universal temperature response caused 13 to 22 day decreases, under both 3° and 6°C night temperature/day temperature (NT/DT) difference, for both early and late maturing lines. The decrease in days to FF that appeared to result from extending DL was due to the attendant and simultaneous extending of the duration of DT and decreasing of the duration of NT. Starting from environments combining intermediate to longest DLs with intermediate to highest Ts, which environments had the fewest days to FF, on the contrary, increases in days to FF occurred as DL was further extended and/or as T was further raised. This photoperiod-temperature response (Pp-T response) caused 2 to 5 day increases in days to FF for early-maturing photoperiod-insensitive lines, and 10 fold larger increases of 40 to 53 days for late-maturing, photoperiod-sensitive lines. The gene(s) conditioning the late-maturing, photoperiod-sensitive phenotype, therefore, caused a 10-fold increase in the days of delay to FF, i.e. of a Pp-T response that is weakly expressed in the early-maturing photoperiod-insensitive genotype. The Pp-T responses of the photoperiod insensitive and sensitive genotypes were both half as large, 0 to 4 and 17 to 29 days, respectively, when the NT/DT difference was 3° rather than 6°C; there was also a requirement for a higher T to activate the Pp-T response. This commonly called photoperiod response, was called the Pp-T response because it was altered as much by T as by DL.

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Switchgrass (Panicum virgatum L.) is one of the perennial, native, warm-season grasses recommended as a component of wildflower meadows. Seed treatments to alleviate low seed vigor and seed dormancy of switchgrass would enhance establishment of either plug transplants or seedlings after direct sowing into the meadow. “Heavy” seeds (45.5 mg/50 seeds) of open-pollinated switchgrass stored under cool and dry conditions (average 13 °C, 30% relative humidity) for 24 months had higher germination percentage than “light” seeds (26.0 mg per 50 seeds). In factorial combination, the heavy seeds were subjected to acid scarification (8 M H2SO4 for 5 min), sodium hypochlorite treatment (5.25% NaOCl for 15 min), and moist chilling (prechilling in 0.2% KNO3, for 14 days). Acid scarification followed by NaOCl treatment additively increased germination, a response that was associated with marked corrosion of the lemma margin in the distal region of the caryopsis, as observed by scanning electron microscopy. Prechilling the seeds following acid scarification and NaOCl further increased germination. All three treatments combined (acid scarification, NaOCl, and prechilling) almost doubled the final emergence and greatly increased seedling shoot dry mass in both a warm and cool postsowing environment. However, the effectiveness of these seed treatments was lost after 32 months of dry storage.

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The percentage of normal grain amaranth seedlings decreased and that of abnormal seedlings increased as threshing cylinder speed increased from 8.1 to 30.7 m·s-1. At the highest threshing speed, seed deterioration (loss of germination and increase in the percentage of abnormal seedlings) was exacerbated by increasing seed storage from 7 to 47 months. Threshing cylinder speeds of 8.1 to 12.8 m·s-1 resulted in similar percentages of normal seedlings as those achieved with hand-harvesting and threshing. Although injury to hand-harvested seeds or seeds threshed at 8.1 m·s-1 was not apparent, scanning electron micrographs of seeds threshed at 12.8 or 22.4 m·s-1 revealed damage to the seedcoat and the endosperm. Damage extended to the embryo when threshing cylinder speed was increased to 30.7 m·s-1.

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Hand-harvested and threshed grain amaranth seeds stored for 6.5 years and combine-harvested and threshed seeds (cylinder speed 26.4 m·s-1) stored for 9.5 years were subjected to several osmotic priming treatment. The selected priming treatment (–1.25 MPa polyethylene glycol at 15C for 10 days) increased percent radicle emergence of hand-harvested seeds and mechanically damaged, combine-harvested seeds and resulted in germination rates that were at least as high as those achieved with other priming treatments. In an incubator test, priming increased percent radicle emergence of hand-harvested seeds only at 15C; however, it increased percent radicle emergence of combine-harvested seeds at 15 and 35C. Priming also increased radicle emergence rate, but this response was more pronounced and exerted over a wider temperature range for the older, lower-vigor, combine-harvested seeds than for the younger, higher-vigor, hand-harvested seeds. In a greenhouse test, hand-harvested seeds had a higher percentage of normal seedlings and a lower percentage of abnormal seedlings than combine-harvested seeds. Priming had no effect on these variables. As a result of priming, normal seedling emergence rate and shoot fresh weight were higher from combine-harvested seeds than from hand-harvested seeds, such that values of these variables for primed, combine-harvested seeds were at least equal to those for nonprimed, hand-harvested seeds. Thus, the invigorating effect of priming was more pronounced for the lower-vigor, mechanically damaged, combine-harvested seeds than for the higher-vigor, hand-harvested seeds.

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