Weight Of Whole Plant Research Articles

Overexpression of aspen sucrose synthase gene promotes growth and development of transgenic Arabidopsis plants

In plants, sucrose synthase (SUS) enzymes catalyze conversion of sucrose into fructose and UDP-glucose in the presence of UDP. To investigate the impact of overexpression of heterologous SUS on the growth and development of Arabidopsis, we transformed Arabidopsis plants with an overexpression vector containing an aspen SUS gene (PtrSUS1). The genomic PCR confirmed the successful integration of PtrSUS1 transgene in the Arabidopsis genome. PtrSUS1 expression in transgenic Arabidopsis plants was confirmed by RT-PCR. The SUS activity was dramatically increased in all transgenic lines examined. The three selected transgenic PtrSUS1 lines exhibited faster growth and flowered about 10 days earlier compared to untransformed controls, and also possessed 133%, 139%, and 143% SUS activity compared to controls. Both fresh weights and dry biomass yields of the whole plants from these three selected transgenic lines were significantly increased to 125% of the controls. Transgenic PtrSUS1 lines also had a higher tolerance to higher concentration of sucrose which was reflective of the increased SUS activity in transgenic versus wild-type plants. The growth differences between wild-type and transgenic plants, either in root and hypocotyl length or in fresh and dry weight of whole plant, became more pronounced on the media containing higher sucrose concentrations. Taken together, these results showed that the early flowering, faster growth and increased tolerance to higher sucrose in transgenic lines were caused by the genome integration and constitutive expression of the aspen PtrSUS1 gene in transgenic Arabidopsis.

THE INFLUENCE OFAPPLICATION METHODS OF POTASSIUM FERTILIZATION ON GROWTH, PODS YIELD AND ITS QUALITY OF PEA PLANTS

Two field trails were conducted out during the season of 2006/2007 and 2007/2008 to study the influence of soil dressing of potassium fertilizer at rates of 100, 200 and 300 kgs./fed. as potassium sulphate (48.5 % K2O) as well as foliar application of liquid potassium contained K2O 36.5 % and sulphure 26.0 % as twice and/or 3 times) on growth, yield and its quality of pea plant. The important findings are as follows: 1. All plant growth parameters recorded their highest values when pea plants received 300 kgs. /of potassium sulphate. The increments in fresh and dry weight of whole plant over that plants which supplied 100 kgs/fed. amounted by 34.9 and 56.9 respectively in 1st season and by 48.6 and 49.3 % for the same respective in 2nd season. Also that pea plants which received liquid potassium 3 time by 10 day intervals gained the vigor plant growth. 2. Pea plants which fertilized by the highest rate of K (300 kgs./fed.) recorded an increase in total and early pods yield over than that plants received medium and low potassium level. The enhancement in total pods weight amounted by 10.01, 34.4 % in 1st season and by 16.1 and 31.1 in 2nd one respectively. 3. The best physical quality of pea pods expressed as average number/plant length and diameter recorded their highest significant values when soil was dressed by 300 kgs./fed. Of potassium sulphate. Moreover, foliar application of pea plant by liquid potassium 3 times gained the heaviest total and early pods yield as well as its best physical quality of pods. 4. With increasing potassium fertilizer of soil dressing and/or the numbers of liquid spraying gained an increase in the nutritional values of pea pods as expressed by protein and carbohydrate content as well as N, P and K.

Variation Laws of Anthocyanin Content in Roots and Their Relationships with Major Economic Traits in Purple-Fleshed Sweetpotato [ Ipomoea batatas (L.) Lam

Variation laws of anthocyanin content in root during the development and among the varieties, and their relationships with major economic traits in purple-fleshed sweetpotato [ Ipomoea batatas (L.) Lam] were studied in the present article. The dynamics of 20 economic traits in 13 purple-fleshed sweetpotato varieties at 20, 40, 60, 80, 100, 120, and 140 d after their transplanting were investigated, and these traits included anthocyanin content in root, length of the longest vine, number of base branches, root number, dry matter contents in stem, foliage and root, fresh/dry weight of root, fresh/dry weight of stem, fresh/dry weight of foliage, fresh/dry weight of stem and foliage, fresh/dry weight of whole plant, and rations of photosynthate to root, stem, and foliage. The correlations between the variations of anthocyanin content and the other 19 economic traits among varieties and during the whole developing stages, and the correlations of daily increase of anthocyanin content with other 10 kinds of yields were analyzed. The results showed that: (1) During the whole development, the anthocyanin content had three variation types, i.e. a slow-increase type, a fluctuating-change type, and a deviousrising type, and had different responses to the growth of length of the longest vine, number of base branches, fresh/dry yield of root, and photosynthate allotments. (2) The anthocyanin contents among 13 varieties began to have significant difference after 20 d, and showed completed differentiation during 40–100 d, which had significantly negative correlationships with the number of base branches, fresh/dry yield of root, photosynthate allotment ratio to root, and had significant positive correlationships with dry matter content of root, length of the longest vine, fresh/dry yield of stem, dry yield of whole plant and photosynthate allotment ratio to foliage. (3) Because of the significantly negative correlation between daily increase of anthocyanin content and dry matter weight of root, the anthocyanin accumulation competed with dry matter accumulation for photosynthate in root, and the competitive relation was resolved in different ways in different purple-fleshed sweetpotato (PFSP) varieties. So, there had three variation types of anthocyanin content among PFSP varieties during their development, and had different correlations between these variations of anthocyanin content and the major economic traits.

질소 관비량 절감이 토마토 생육 및 수량에 미치는 효과

토마토의 생육, 수량, 물과 질소 이용율 등에 미치는 질소 관비 처리효과를 살펴보기 위하여 토양검정시비량의 0%, 40%, 60%, 80%, 100%에 해당하는 질소량은 15회에 걸쳐 토마토에 점적관비 하였으며, 질소 점적관비 효과는 질소관행시비구(기비와 추비를 60:40의 비율로 표층시비)와 비교하였다. 질소관비량 증가로 토마토의 초장과 건물중은 증가하였으나, 경경은 현저한 차이가 없었다. 질소관비량 증가에 따른 상품과실수 증가로 토마토수량은 증가하였다. 질소관비처리구의 과실수량은 질소관비처리량에 따라 <TEX>$9{\sim}33%$</TEX> 가량 증가하였으며, 토양검정시비량의80%(NF80처리구)에 해당하는 <TEX>$176kg\;ha^{-1}$</TEX>의 질소 관비시(96.6 mg <TEX>$L^{-1}$</TEX>) 과실은 최대수량을 보였다. 질소관비량 증가로 토마토 부위별 건물중과 질소흡수량은 증가하였다. 전체건물중 대비 과실 중량의 비율은 관행에 비해 질소관비처리구들에서 <TEX>$2.6{\sim}5.3%$</TEX> 증가하였고, 과실중 질소분배량은 <TEX>$3.7{\sim}21.7%$</TEX> 가량 증가하여 질소 관행처리에 비해 질소 관비처리구에서 과실로의 질소분배 및 동화산물 전이가 효과적으로 진행되는 것으로 판단되었다. 한편 질소 관비량 증가로 인한 질소흡수량은 증가하였으나, 질소 흡수율은 감소하는 경향이었다. 그럼에도 불구하고 질소관비처리구의 질소흡수율은 <TEX>$71.8{\sim}102.3%$</TEX> 범위로서 질소관행 처리구의 45%와 비교할 때 현저하게 높았다. 반면에 질소관비처리구의 물이용효율성은 <TEX>$327{\sim}361kg/ha\;cm^{-1}$</TEX>로서 관행 질소 처리구의 <TEX>$324kg/ha\;cm^{-1}$</TEX>보다 높았으며, NF80 처리구의 경우 <TEX>$361kg/ha\;cm^{-1}$</TEX>으로 가장 효율적으로 물을 이용한 것으로 나타났다. 결과적으로 과실의 상품수량, 상품율, 물 이용효율성 등을 고려할 때, 토양검정시비량의 80%에 해당하는 질소량을 관비시 토마토의 생육 및 수량 증가에 가장 효과적인 것으로 판단된다. To investigate the effect of N fertigation on the growth, yield, and water and nitrogen use efficiencies during tomato cultivation, seedlings were transplanted in a sandy loam soil under plastic film house condition. 0, 88, 132, 176, <TEX>$220\;kg\;ha^{-1}$</TEX> N rates, which correspond to 0 (NF0), 40 (NF40), 60 (NF60), 80 (NF80), 100% (NF100) N level of soil test-based N fertilization, were injected weekly through drip irrigation system for 15 weeks in N fertigation system, and the control (conventional N treatment) was installed for comparison. Herein, nitrogen was applied by top-dressing with 60% as a basal and 40% as additional fertilizer. There was little different in stem diameter growth among N fertigation treatments, but plant height and dry matter increased with increasing N fertigation rates as well as in N conventional treatment. Tomato yield was increased with increasing the number of marketable fruits in N fertigation treatments, and the fruit yield was maximized in NF 80 treatment (<TEX>$176\;kg\;ha^{-1}$</TEX> N supply or <TEX>$96.6\;mg\;L^{-1}$</TEX> N injection). Dry matter productivity and nitrogen uptake amount were significantly increased with increasing N fertigation rates. The ratio of fruits to the dry weight of whole plant was decreased with increasing N fertigation rates, but this ratio was <TEX>$2.6{\sim}5.3%$</TEX> higher in N fertigation treatments than in the control. In addition, the ratios of nitrogen distributed toward fruits in N fertigation treatments were <TEX>$3.7{\sim}21.7%$</TEX> higher than that of control. The apparent N recovery percentages showed significantly higher values as <TEX>$71.8{\sim}102.3%$</TEX> in N fertigation treatments, compared to 45% in N conventional treatment. Water use efficiency was significantly increased by fertigation system with the maximum <TEX>$361\;kg/ha\;cm^{-1}$</TEX> in NF 80, which is comparable to <TEX>$324\;kg/ha\;cm^{-1}$</TEX> of the conventional treatment. Conclusively, N fertigation system was effective on increasing tomato productivity and nutrient efficiency as well as 20% reduction of N fertilization level.

Root confinement and irrigation frequency affect growth of ‘Rough lemon’ (Citrus limon) seedlings

Introduction. Root restriction occurs when seedlings are grown in increasingly small containers and it reduces plant growth in different ways. Therefore, the objectives of our study were to investigate the effects of varying container sizes and irrigation frequency on growth parameters of 'Rough lemon' (C. limon) plants Maseno, Kenya. Materials and methods. The treatments tested the effect of three container volumes (1.7 L, 2.7 L and 4.5 L) and three irrigation frequencies (every day (W1), every two days (W2) and every 3 days (W3)). The design of the experiment was completely randomized with three replications. Growth parameters studied were plant height, canopy height, shoot and root weight, number of leaves and shoot to root ratio. Results and discussion. Increasing container volumes generally increased the height of plants, height of canopy, weight of whole plants and weight of roots, but it did not affect number of leaves, stem diameter or shoot to root ratio. Irrigation frequency increased number of leaves, height of plants, height of canopy, stem diameter and weight of shoots and roots, but this factor had no effect on weight of whole plants. These findings are explained by reduced root restriction in the largest container volumes. Conclusion. Increasing container volumes from 1.7 L to 4.5 L and irrigation frequency from every 3 days to every day increases plant growth as expressed in the various plant growth parameters. Nigeria / Citrus limon / plant propagation / plant nurseries / planting stock / growth / container planting / irrigation

The effect of plastic mulch and row covers on the growth and physiology of cucumber

To determine the effectiveness of black plastic mulch alone and in combination with row covers, on growth and physiological changes of cucumber plants, 6 treatments were established in a randomised complete block design with 4 replications: bare soil (control); black polyethylene mulch alone (B); B plus a clear cover of perforated polyethylene (BRCP); B plus a white cover of perforated polyethylene (BRWP); B plus an Agribon cover of polypropylene (BRA); and B plus a Kimberly farm row cover (BRK). For the plants grown with mulch or mulch combined with row covers, the dry weight of leaves 50 days after seeding (DAS), and the dry weight of whole plants (at 50 and 110 DAS) were significantly (P&lt;0.05) different from the control. Early yields of treatments B, BRCP, BRWP, BRA and BRK were 2.1, 1.9, 2.6, 1.9 and 2.4 times higher than the control, which yielded 10 t/ha. Total yields were increased by 9.7, 15.4, 19.8, 14.9 and 20 t/ha, over the control which yielded 104 t/ha. Increases in plant dry weight explained the changes in yield. Stomatal conductance may explain in part, the increase in photosynthetic rate, but may not explain yield increase.

Relationship between salt tolerance and proline accumulation in Australian acacia species

The effects of salinity on the seedlings of five acacia species, Acacia ampliceps, A. salicina, A. ligulata, A. holosericea, and A. mangium were studied with respect to mortality, growth, and proline accumulation. There was marked variation among the species in their response to salinity. A. ampliceps showed the highest level of salt tolerance among the five acacia species. In contrast, A. holosericea and A. mangium were classified as the least tolerant. The concentration which caused 100% mortality in 2-week-old seedlings during 1 week of treatment was 2.5% (w/v) and 1.5% NaCl for A. ampliceps and A. holosericea, respectively. The dry weights of whole plant of two acacia species decreased markedly under the above salt stress conditions. Proline accumulation was found in leaves and roots after NaCl treatment. The maximum level of proline accumulation in A. holosericea was about twice as great as that in A. ampliceps throughout the stress period. Thus, the level of proline accumulation was not related to the degree of salt tolerance in these acacia species, although a positive correlation between the extent of salt stress and the accumulation of proline was found.

EFFECTS OF SPENT ENGINE OIL ON THE GROWTH PARAMETERS, CHLOROPHYLL AND PROTEIN LEVELS OF AMARANTHUS HYBRIDUS L

The susceptibility of Amaranthus hybridus L. seedlings to spent engine oil was investigated in soil supplemented with concentrations of oil ranging from 1–5 percent v/w. Parameters considered were relative growth rate (RGR), leaf area ratio (LAR), whole plant height, leaf area, leaf number, chlorophyll and protein levels. A relationship was found to exist between the inhibitory effects and the treatment concentrations. After seventy days growth in the treated soils, the mean height and leaf area of plants in soils treated with 5 percent spent engine oil were 27.0±1.25 cm and 5.63±0.36 cm2. These were significantly different (at p=0.05) from the respective values of 41.4±0.8 cm and 13.44±0.22 cm2 for the control plants. Levels of total chlorophyll (per gram fresh weight of leaves) and protein (per gram dry weight of whole plant) were higher in the control plants compared with those grown in oil treated soil. Results obtained from the growth analysis showed the inhibitory effects of spent engine oil on Amaranthus hybridus L.

A simple method for estimating the nitrate nitrogen concentration based on dry matter in standing sorghum (Sorghum bicolor Moench) using stem juice test and dry matter content

A simple method was developed for estimating the nitrate nitrogen (NO3-N) concentration in standing sorghum (Sorghum bicolor Moench) crop at maturity. In the method, the concentration of NO3-N in whole plants on a dry matter basis can be accurately estimated by multiplying the concentration factor (CF, NO3-N concentration of stern on a fresh matter basis) by the dilution factor (DF, dry matter partitioning ratio of stern divided by the dry matter content of stern or fresh matter weight of stern divided by the dry matter weight of whole plant). CF was linearly correlated with the NO3-N concentration in stern juice squeezed from stern discs with a thickness of 1 cm obtained by cutting horizontally at a location corresponding to a ratio of 25% to the total stern length. CF can be estimated by multiplying the NO3-N concentration in stern juice by a factor of 0.68 or 0.53 for grain and dual purpose types or sorgo type, respectively. The values of the coefficients of determination (R 2) of the linear regression were above 0.7. When DF was plotted with the dry matter content of whole plants (DM%), regression curves were obtained for both sorghum types with R 2 > 0.8. The equations were as follows: DF= 0.00721X 2-0.503X + 10.72 for grain and dual purpose types, DF=0.00445X 2 -0.337X + 8.86 for sorgo type, where X is DM%. The NO3-N concentrations estimated by multiplying CF by DF enabled to predict the measured NO3-N concentrations with an R 2 of 0.873.

Variation in calcium levels leads to changes in the copper metabolism in barley

Barley (Hordeum vulgare L.) cv. Jyoti was grown in refined sand at three levels of Cu, namely, deficient (0.01 µM), normal (1 µM), and excess (100 µM), each at three levels of Ca, low (0.04 mM), adequate (4 mM), and high (8 mM). Low Cu levels resulted in a decrease of the dry weight of whole plant and in the leaf chlorophyll content as well as Cu and Fe concentrations and activity of polyphenol oxidase and in an increase of the activities of ribonuclease and peroxidase and concentration of reducing sugars. These effects were further accentuated by a combined deficiency in Cu and Ca. The synergy between Cu and Ca was manifested when a low Ca level aggravated the effects of excess Cu by further reducing the dry weight and concentration of chlorophyll, leaf Fe and increasing the sugar concentration and activities of polyphenol oxidase and ribonuclease. In barley the Cu toxicity effects such as reduced dry weight, increase of leaf Cu, Ca, and reducing sugar concentrations, and stimulation of the activity of polyphenol oxidase were further enhanced by excess Ca. At all three levels of Ca, the addition of a normal Cu level to low Cu plants alleviated the Cu deficiency effects except for α-amylase activity, after 48 h. The effects of Ca deficiency were partially alleviated upon the resumption of Ca supply to Ca deficient leaf discs.

Effects of mycorrhizae, established from an existing intact hyphal network, on the growth response of capsicum (Capsicum annuum L.) and tomato (Lycopersicon esculentum Mill.) to five rates of applied phosphorus

The growth response of 2 vegetable crops to 5 rates of applied phosphorus (P)in the presence or absence of an existing network of extraradical mycorrhizalmycelium was determined in 2 greenhouse pot experiments (Expt 1, autumnwinter; Expt 2, summer autumn) using a low-P growth medium (6 or 5 mgNaHCO3-extractable P/kg for Expt 1 or 2,respectively). In both experiments, capsicum(Capsicum annuum L.) and tomato(Lycopersicon esculentum Mill.) plants were grown at 0(P1 ), 9.2 (P2), 27.5(P3 ), 82.5 (P4 ), or 248(P5) mg P/kg oven-dry soil (spot-placed at sowing)within a nylon mesh (pore size 44 µm). The mesh excluded roots from theoriginal sunflower (Helianthus annuus L.) host plants,to which either live (VAM+) or killed (VAM–) mycorrhizal[Glomus etunicatum Becker &amp; Gerdemann andGlomus mosseae (Nicol. &amp; Gerd.) Gerdemann &amp; Trappe] inoculum was added at sowing. The mesh did allow fungal hyphae togrow into the growth medium contained by the mesh.Whereas VAM+ plants generally had higher P concentrations in indextissues than VAM– plants at low P rates, a concomitant increase in drymatter yield was restricted to the P1 rate. AtP1 in Expt 2, the increase in the dry weight of wholeplants as a result of VAM colonisation was as large as 91.7-fold and 17.9-foldfor capsicum and tomato, respectively. Root starch analysis indicated that thelower dry matter yields of VAM+ plants than of VAM– plants at≥P2 could be attributed to insufficient photosynthateproduction by VAM+ plants to meet the carbon (C) demand of both host andendophytes within the relatively low-light environment of the greenhouse(average daily solar irradiance of 8.4 MJ/m2 forExpt 1 and 13.4 MJ/m2 for Expt 2).The growth response of vegetable crops grown within the greenhouse fromcolonisation by an established mycorrhizal mycelium appears to depend on acritical balance of P and C supply; i.e. at P1, P wasmore limiting than C, and the increased uptake of P as a result ofcolonisation of plant roots by VAM resulted in a growth response. At higher Prates, C was more limiting than P due to low light in the greenhouse, and theadditional demand for photosynthate imposed by the endophytes on the hostresulted in a growth depression relative to non-mycorrhizal plants.

First Report of Cylindrocladium Black Rot (C. parasiticum) on Partridgepea and Sicklepod.

Partridgepea (Cassia fasciculata Michx.) is grown in the southeastern U.S. in food plots for game birds. In 1997, numerous dead plants were observed in a commercial planting for seed production. Perithecia of Calonectria ilicicola Boedijin & Reitsma (imperfect stage: Cylindrocladium parasiticum Crous, Wingfield & Alfenas), a serious pathogen of peanut (Arachis hypogaea L.), were found on the crown of diseased plants. Two isolates each from partridgepea and peanut were grown on potato dextrose agar for 5 weeks. Microsclerotia produced were added to a 2:1 mixture of pasteurized field soil and Pro-mix potting medium (25 microsclerotia per g of mix). Both infested and noninfested potting mixes were put in Super Cell Cone-Tainers (Stuewe & Sons, Corvallis, OR) in the greenhouse and planted to one pre-germinated seed each of either peanut or partridgepea (10 replications). Soil moisture was kept at field capacity and after 7 weeks root rot severity (0 to 4 scale with 4 = dead plant) and fresh weight of whole plants and roots were determined. Mean disease ratings for peanut were 2.1 and 2.5 with the peanut and partridgepea isolates, respectively, and 0.1 for the controls. Mean disease ratings for partridgepea were 3.2 and 3.2 with the peanut and partridgepea isolates, respectively, and 1.0 for the controls. Peanut and partridgepea plant weights were reduced by 50 and 68%, respectively, compared with controls. Reductions in root weights were similar to those for whole plants. The pathogen was consistently recovered from diseased roots. In summary, all four isolates were pathogenic to both hosts, but partridgepea was more susceptible (P ≤ 0.05) than peanut to C. parasiticum. Sicklepod (Senna obtusifolia (L.) H. Irwin & Barneby), one of the most troublesome weeds in the southeastern U.S., was previously observed to have black rot symptoms and perithecia of C. ilicicola on the crowns of diseased plants. Plants grown in soil infested with an isolate of the fungus from sicklepod exhibited typical symptoms and the pathogen was reisolated from diseased tissue. Rotation with soybean (Glycine max L.) traditionally has been the major concern for peanut production in fields with a history of Cylindrocladium black rot; however, these additional hosts also should be considered.

Relationship between biomass and surface area of six submerged aquatic plant species

Mathematical relationships relating the biomass to the surface area of Elodea canadensis Michx., Myriophyllum spicatum L., Nitellopsis obtusa (Desv.) J.Gr., Potamogeton lucens L., Potamogeton pectinatus L. and Potamogeton perfoliatus L. were developed. The methods leading to these relations are presented for plants from Lake Geneva (Switzerland). Results include three sets of data for each species: leaves, stems and whole plant. Differences were evidenced according to plant species; for a same biomass E. canadensis and M. spicatum offered the highest surface area, P. pectinatus and N. obtusa the lowest. For 1.0 g dry weight of whole plant, the surface area was 1255 cm 2 for E. canadensis, 1205 cm 2 for M. spicatum, 560 cm 2 for N. obtusa, 653 cm 2 for P. lucens, 500 cm 2 for P. pectinatus, and 762 cm 2 for P. perfoliatus. Plants with dissected morphology did not necessarily offer the largest surface area per unit biomass.

Effects of Enhanced Ultraviolet-B Radiation with a Modulated Lamp Control System on Growth of 17 Rice Cultivars in the Field.

To investigate the effects of enhanced UV-B radiation on the growth of rice, 17 lowland cultivars from a variety of geographical regions were pot-grown for two months in the field under eight 40W fluorescent sunlamps filtered with 0.13mm thick cellulose diacetate film (Transmission down to 290nm) in Tsukuba, Japan (360°01′N, 140°07′E, 25m elevation). As a control, 0.13mm thick Mylar D film, which effectively absorbs radiation below 320nm, was used in place of the cellulose diacetate film. Output of the UV lamps in the field was supplied by a feedback control system throughout the day to provide a supplemental levels proportional to ambient solar UV-B. UV-B irradiance weighted with generalized plant response action spectrum normalized at 300nm (UV-BBE) was controlled to 2.67 tims control plots at the plant height from August 25 to October 22, 1992. No significant effects of the two-month supplemental UV-B irradiation treatment were detected on any growth parameters for all the cultivars. For example, plant height, tiller number, heading date and dry weight of whole plants were unaffected by extremely high UV-B irradiation. On the other hand, the concentration of UV-absorbing compounds and chlorophyll in rice leaves exposed to supplemental UV-B tended to increase in many cultivars, although these differences were not statistically significant except a few cultivars.

Acceleration of 13C-labelled photosynthate partitioning from leaves to panicles in rice plants exposed to chronic ozone at the reproductive stage

To investigate the effects of low (0·05 μmol/mol) and relatively low (0·10 μmol/mol) concentrations of ozone on photoassimilate partitioning, rice plants grown in a water culture were fed with 13C-labelled carbon dioxide at the reproductive stage in an assimilation chamber with constant concentration of 12CO 2 and 13CO 2. Rice plants were exposed to ozone 4 weeks before and 3 weeks after 13CO 2 feeding. The dry weight of whole plants decreased with increasing ozone concentration, whereas net photosynthetic rate (apparent CO 2 uptake per unit leaf area) was unaffected, compared with the control, at the time of 13CO 2 feeding. Dry matter distribution into leaf sheaths and culms was reduced more than that into leaf blades by ozone exposure. Although panicle dry weight per plant was reduced by ozone, the percentage of panicle dry weight to the whole plant tended to increase considerably. Exposure to ozone accelerated translocation of 13C from source leaves to other plant parts. Partitioning of 13C to panicles and roots was higher under ozone treatment than in the control. Respiratory losses of fixed 13C from plants tended to decrease under treatment with ozone. The increase in photoassimilate partitioning in panicles can be considered to be an acclimation response of rice plants to complete reproductive stage under the restricted biomass production caused by ozone.

Development of the Fifth Leaf is Indicative for Whole Plant Performance at Low Temperature in Tomato

In the search for early-detectable selection criteria for growth at low temperature conditions in tomato, first the initiation and growth of individual leaves was analysed. Scanning electron microscopy revealed that the first four primordia had already developed during the germination period at 25°C. The primordium of the fifth leaf, however, was initiated after the transfer of seedlings to the experimental conditions. The increase in length of the first three leaves, and to a lesser extent of the fourth leaf, was considerably smaller in comparison with that of later formed leaves. Moreover, the morphology of the first three to four leaves was deviant, whereas the others showed the normal compound leaf architecture. All these results indicated that the fifth leaf was the earliest formed leaf with growth characteristics that might reflect the growth potential of the whole plant.Development of the fifth leaf was tested as a marker for whole plant growth. At three temperature, 18, 15 and 12°C, growth responses of the fifth leaf were similar to that of whole plants in four tomato genotypes: Line A, Line B, Premier and MXXIV-13. Significant differences in relative growth rate of dry weight of whole plants and fifth leaves (RGRW)and of leaf area of the fifth leaves (RGRLA between two fast growing and two slow growing genotypes were found. No genotype by temperature interaction for RGRW and RGRLA was found, indicating that the effect of temperature decrease was similar for the four genotypes.The structure of the mature fifth leaf of one fast and one slow growing genotype, Line A and MXXIV-13, was analysed. For both genotypes, leaves were small and thick at low temperature, 12°C. The total number of epidermis and palisade parenchyma cells per leaf was smaller but the size of the cells developed at 12°C was larger than at 18°C. Consequently, the slow growth at 12°C was due to a low rate of cell division. At both temperatures, the fifth leaf to MXXIV-13 was smaller compared to that of line A. Since the size of the cells were similar, the smaller leaf size was due to lower number of leaf cells.The results confirm the suitability of the growth, especially expressed as RGRLA , of the fifth leaf as a nondestructive market for vegetative development of tomato at low temperature. Growth differences between genotypes were mainly reflected by differences in cell number of leaves, which might be correlated with genetically determined differences in cell number of leaf primordia.

Effect of potassium rate on growth, quality, chemical composition, and winter hardiness of perennial ryegrass

Abstract Seven potassium (K) rates (0, 50, 150, 350, 450, 550, and 650 kg K/ha) were used to determine the optimum rate of K for turf‐type perennial ryegrass during the winter based on turf growth, quality, and winter hardiness. Turf density, color, growth, and winter hardiness were increased as the rate of K application increased up to 350 kg K/ha. However, there were no beneficial effects of K application beyond that rate. Potassium content of the whole plant was 1.72% of the dry matter at the 350 kg K/ha rate. Calcium and Mg contents of the plant were reduced as the result of K application, and a reduction in growth and K content was detected at the higher K application rates. It is suggested that the optimum K rate for perennial ryegrass is about 350 kg K/ha under our experimental conditions in the winter, and that the K content should be about 1.72% of dry weight of whole plant.

Effects of simulated acid rain on the growth of agricultural crops

Three species of crops, radish, spinach and bush bean, were exposed to simulated acid rain at pH 5.6 (control) to 2.5 throughout their growing periods. Plants were subjected to acid rain treatment three times a week, for one hour with 10mm of precipitation at a time. All the plants exposed to simulated acid rain falls at pH3.0 or below produced visible injury on the leaves. The visible injuries were severe on the cotyledons of radish and spinach and primary leaves of bush bean exposed to rain at pH 2.7 and 2.5, which resulted in the growth reduction of plants at early stages of growth compared to pH 5.6. In none of the cases in this study did treatment at pH 3.0 or higher significantly affect the growth of leaf area or dry weight of whole plants in three species. These results suggest that current ambient levels of rain acidity in Japan, where annual mean pH value is about 4.6, may not affect growth in the three species of crops tested in this study.

Effects of ultraviolet-B radiation on the growth of cucumber plants

Three cucumber cultivars (cv. Suyo, Shimoshirazu-jibaikyuuri and Tsukemidori) were grown for 3 weeks in sun-lit environmental glass chambers under UV-B (290-320nm) irradiation from six 20W fluorescent sunlamps using 0.10mm polyvinyl chloride sheeting and UV-B free control conditions using 0.10mm polyester film. Plants were irradiated with three levels (0, 244 and 381mW m-2) of biologically effective UV-B (UV-BBE) for 8h (8 a.m. to 4 p.m.) a day. The levels of UV-BBE irradiance at Tsukuba (36°N latitude) were about 250mW m-2 at noon in summer under clear sky conditions. Visible foliar injury (yellow lesions and glazing) due to UV-B irradiation occurred on the leaf surface. The leaf area and dry weight of whole plants of the three cultivars of cucumber were significantly reduced and decreased with increasing intensities of UV-BBE irradiation. Growth parameters of the relative growth rate (RGR), the net assimilation rate (NAR) and leaf area ratio (LAR) were reduced by medium and high UV-BBE irradiation throughout irradiation periods. Specific leaf area (SLA) decreased remarkably due to UV-B, which indicates that plants exposed to UV-B increase their leaf thickness. This increase of leaf thickness might be an adaptation mechanism against increased UV-B radiation.

Differential response of citrus rootstocks to aluminum levels in nutrient solutions: I. plant growth2

Abstract The objectives of this study were to determine and compare the Al tolerance of selected citrus rootstocks. Six‐month‐old seedlings of five citrus rootstocks were grown for 60 days in nutrient solutions. The solutions contained 7 levels of Al ranging from 4 to 1655 μM and similar P concentration of 28 μM. The nutrient solution pH was maintained at 4.0±0.1 and the temperature at 25±1°C. At high Al treatment levels, plants had thickened root tips and root caps covered with black gelatinous material. At high levels of Al treatments, seedlings of some rootstocks had yellow, mottled, and withered new leaves near end of experiment. New‐growth root lengths and shoot height responded differently to Al concentrations in the nutrient solution. New‐growth fresh weight of whole plants appeared to be the most sensitive indicator of Al tolerance. Based on response of fresh weight of whole plants to Al concentrations, relative Al tolerances of the rootstocks were Cleopatra mandarin > rough lemon > sour orange > ...