Summer-grown Plants Research Articles

Yield, Quality, and Resources Use Efficiency of Wild Rocket Baby Leaves Grown under Different Controlled Environment Systems and Various Growing Seasons

Wild rocket is a leafy vegetable with economic interest as a consequence of baby leaf ready-to-eat salads. The climate crisis is expected to influence wild rocket production, but these effects could be confronted with cultivation in greenhouses and plant factories with artificial lighting (PFALs). Climate responses are related to growing seasons. Our objective was to test the impact of two growing seasons, winter and summer, on the growth and physiology of wild rocket baby leaves in different controlled environment systems (greenhouse and PFAL). The growth cycle was reduced by 27% in the PFAL compared to the greenhouse during winter. Summer yield was greater in the greenhouse, but leaf number and area were greater in the PFAL. The lowest water use efficiency was recorded in the greenhouse during summer. Energy use efficiency was lower in PFAL compared to the greenhouse. Land use efficiency was not affected by the growing system, but in PFALs it is able to increase it by growing in vertical layers. Relative chlorophyll content and total soluble solids were enhanced in the greenhouse. The photosynthetic efficiency evaluation showed considerable stress in summer-grown plants in the greenhouse, as shown by PIABS and φP0. In general, the production was similar in the PFAL regardless of seasons.

Influence of Cultivar and Seasonal Growing Environment on Growth and Postharvest Characteristics of Single-shoot Pot Rose Plants

Rooted liners of pot rose (Rosa L.) cultivars Meiferjac, Meigagul, Meighivon, Meishulo, Ruijef, Ruidodo, and Ruirosora were used to study the influence of cultivar and seasonal growing environment on growth and postharvest performance. Single-shoot plants were grown in controlled environment chambers simulating summer (30 °C day/21 °C night cycle with a 14-hour photoperiod) and winter (21 °C day/16 °C night cycle with a 10-hour photoperiod) greenhouse growing conditions. At flower developmental stage 2 (showing color, calyx reflexing, no petals reflexed), the plants were placed in a continuously lighted simulated interior evaluation room at 21 ± 1 °C under 15 μmol·m-2·s-1 photosynthetic photon flux from cool-white fluorescent lamps for postharvest evaluations. Plants had quicker flowering, smaller flower diameter, more compact growth, and smaller leaf area when grown under the summer environment compared to the winter environment. Most cultivars exhibited greater flower longevity on summer-grown plants when compared to winter-grown ones. `Ruirosora' did not exhibit this difference due to exceptional longevity on winter-grown plants. Also, the use of single-shoot plants was shown to be a potentially useful way to increase replication in small growing environments such as growth chambers.

Floral transition in lisianthus ( Eustoma grandiflorum)

Floral transition was studied in lisianthus [ Eustoma grandiflorum (Raf.) Shinn.] plants grown in a greenhouse at two planting times (winter and summer) under two photoperiod regimes: long day (LD) and short day (SD), 16 h/8 h and 8 h/16 h (light/dark), respectively. Morphological analyses of the flower meristem of the lisianthus cultivar ‘Heidi Deep Blue’ revealed three distinct stages of development: (1) sepal primordia, (2) petal and stamen primordia (almost simultaneously), and (3) carpel primordia. The appearance of sepal primordia was taken to mark the floral transition stage. Floral transition was hastened in summer-grown plants and under LD treatment, as expressed by a reduction in both the number of nodes and the time from planting. Stem length from base of plant to floral meristem, as measured at floral transition, was similar in all treatments, regardless of the number of nodes produced. At both planting dates, SD induced a higher number of flowers per inflorescence than LD. This report thus describes the direct effect of environmental factors on floral transition in lisianthus.

Physiological causes for decreased productivity under high salinity in Boma, a tetraploid Chloris gayana cultivar. II. Oxidative stress

In tetraploid cultivars of Rhodes grass (Chloris gayana Kunth) productivity decreases significantly under saline conditions. Two closely related clones of cv. Boma (T and S), exhibiting different degrees of salt tolerance, were compared with determine the physiological causes for such decrease. In those clones, salt tolerance was associated with differences in the proportion of dry leaves, salt gland density, Na excretion rate, and oxidative stress damage. The purpose of this paper is to evaluate whether salt tolerance and oxidative stress development in these clones are related to the activity of two antioxidant enzymes. Experiments were conducted in a greenhouse, in winter and summer, in plants treated with 0, 100, or 200 mm NaCl. In the summer, increases in oxidative damage, as determined by malondialdehyde (MDA) concentration, mirrored decreases in CO2 fixation at high salinity, especially in clone S. In clone T, salinity induced higher increases in Fe-SOD (superoxide dismutase) activity in summer-grown plants, and in ascorbate peroxidase (APX) in winter-grown plants. Oxidative stress induced by low paraquat concentration also induced an increase in Fe-SOD in leaf segments of clone T, and APX was less affected in clone T than in clone S. These results suggest that the clones differ in the control of antioxidant enzymes. Nevertheless, leaf death in winter was not related to increases in MDA, indicating that the association between salinity, leaf senescence and oxidatives stress is also influenced by other factors.

ストックの主枝の生長と開花に及ぼす赤色光または遠赤色光と赤色光／遠赤色光比の影響

The effects of red light and far-red light on the main shoot elongation and flowering of long-day plant stock [Matthiola incana (L.) R. Br.] were compared. During the day, plants were covered with the films which convert light quality of sunlight into different red/far-red photon flux ratio, whereas at night the plants were irradiated with compact self-ballasted fluorescent lamps of red or far-red light. Plants exposed to high red/far-red photon flux ratio during the day and red light at night, flowered late and developed short internodes, whereas the opposite occurred on plants grown under low red/far-red photon flux film during the day and irradiated with far-red light at night, i.e., flowering was advanced and internodes were elongated. The same findings were obtained regardless of planting date. However, the contrast between the two lighting conditions was especially apparent between autumn-sown, winter-cultivated plants, and summer-sown, autumn-cultivated plants because temperatures are colder during the winter flowering period. In this experiment, spring-sown, summer-grown plants had shorter internodes and more leaves ; anthesis was advanced compared with plants sown at other times of the year. This finding will contribute to the efficient production of long-day flowering plant because advancing flowering by far-red light improves the utilization of the horticultural facilities by hastening crop turnover and reducing heating costs in winter.

Effect of Seasons and Irrigation Regimes on Plant Growth and Water-Use of Container-Grown Photinia × fraseri

Abstract Water-use and plant growth of Fraser photinia (Photinia × fraseri Dress) were studied under varying irrigation regimes during 2 different growing seasons, winter and summer. Rooted cuttings were transplanted into 7.57 1 (2 gal) plastic containers containing Metro-mix 500 and greenhouse-grown under 2 irrigation frequencies (3.5 or 7-day intervals) and 3 replacement amounts (100%, 75% or 50% replacement of actual water-use). Increased irrigation frequency significantly reduced plant growth parameters of winter-grown plants, including shoot growth, leaf number, leaf area and shot dry weight. Decreased irrigation amount significantly increased root dry weight. Significant differences were not detected in growth measurements of summer-grown plants suggesting differences between experiments are seasonal in nature. Frequent irrigation resulted in poor plant pelformance under winter growing conditions of lower evapotranspiration (ET); however under summer growing conditions, frequent irrigation did not significantly affect plant growth. Decreased irrigation frequency significantly increased total water-use for winter-grown plants due to increased plant performance. No significant differences in water-use due to frequency in summer-grown plants was found.

Comparative digestibility and anatomy of some sympatric C3 and C4 arid zone grasses

The importance of C4 (panicoid) and C3 (festucoid) leaf anatomy to differences in in vitro dry matter digestibility (DMD) of grasses was assessed using two Australian summer-growing arid zone C4 grasses, Cymbopogon obtectus and Digitaria brownii, and two C3 grasses, Thyridolepis mitcheiliana and Monochather paradoxa. Seed of these sympatric species was collected from a 400 m2 area near Charleville, Qld. Thus the usual problem of confounding C4 and C3 type with species of different environmental adaptation was avoided in this study. Proportions of tissue types in leaf cross sections and DMD were measured for plants grown in a glasshouse under summer (� water stress) or winter ( - stress) conditions. Differences in tissue proportions due to C4 and C3 leaf anatomy were greater than those induced by growth conditions. C4 leaves consistently had less mesophyll and more of the less-digestible epidermis, bundle sheath, sclerenchyma and vascular tissues. Water-stress resulted in leaves with an increased proportion of mesophyll, but differences in tissue proportions between summer- and winter-grown leaves were small. Species were divided into fast (D. brownii and 7, mitchelliana) and slow (C. obtectus and M. paradoxa) leaf development groups for comparison of DMD. Within each group the C3 species consistently had the highest leaf DMD, but across groups the difference of 18-27 days in time to develop a new leaf sometimes overrode the advantage to DMD of the C3 anatomy. Stem DMD did not differ consistently between C4 and C3 species. The DMD was highest for water-stressed material, and higher in winter- than summer-grown plants. The anatomy associated with either C4 tropical or C3 temperate grass genera clearly contributes to difference in DMD between leaves, but variation in DMD associated with leaf age or environment was only in part attributable to differences in tissue proporxions.

Photosynthate transport in stems of Phaseolus vulgaris L. treated with gibberellic acid, indole-3-acetic acid or kinetin.

Gibberellic acid (GA3), indole-3-acetic acid (IAA) or kinetin ((6)N-furfurylaminopurine) applied to the apical regions of decapitated stems of derooted Phaseolus vulgaris plants, promoted (14)C-photosynthate transport to the site of hormone application. Hormonal promotion of acropetal photosynthate transport was associated with significant increases in the pool size of free-space sugars at the hormone-treated region of the stem. The hormone-induced increases in the free-space pool size depended on continued phloem transport in the stem stumps while photosynthate leakage from the sink tissues of the stems was unaffected by the hormone treatments. On the basis of these observations, it is concluded that the increases in the pool size of sugars in the stem free-space results from hormonal action on processes that determine rates of sugar unloading from the sieve element-companion cell (se-cc) complexes. Furthermore, since loading of the se-cc complexes in the stem stumps was stimulated by GA3 and IAA and unaffected by kinetin applied at the loading site, hormonal effects on net unloading from the se-cc complexes must be caused by alterations in the efflux component. For winter-grown plants, it was found that predicted increases in sugar transfer through the stem free-space from the se-cc complexes to the sink tissues could account for the observed hormonal stimulation of photosynthate transport. In contrast, for summer-grown plants the higher sugar concentrations in the stem free-space of control plants approached saturation for the sugar-accumulation process. This caused an attenuation of the responsiveness of sugar accumulation by the stem sink tissues to hormone-induced increases in the pool size of sugars in the stem free-space. On this basis it is proposed that the bulk of photosynthates may move radially from the se-cc complexes through the stem symplast of summer-grown plants.

Disease cycle in New Zealand of light leaf spot of brassicas, induced byPyrenopeziza brassicae

Abstract This paper discusses the role of a pothecia of Pyrenopeziza brassicae Sutton & Rawlinson in the disease cycle of light leaf spot of brassicas. Apothecia survived for up to 27 weeks on the soil surface under a weed canopy but for less than 4 weeks when buried in the soil. Apothecia stored for up to 50 weeks on dry cauliflower residues in the laboratory discharged ascospores when wetted. Ascospores discharged on to glass slides remained viable for up to 8 weeks at about 20°C and 70% RH. Less than 1% of conidia incorporated into unsterilised volcanic loam remained viable after 10 days as determined by direct counts, but bioassay showed that some conidia remained viable for up to 10 weeks. Seeds from severely diseased cauliflower seedheads contained the pathogen but tests indicated that the disease was not seed-transmitted. P. brassicae was not found on any of the common cruciferous weeds present in vegetable brassica crops in the Pukekohe district. Only summer-grown plants of oilseed rape were susce...

Carotenoid changes inBrassica oleraceavar.capitataL. with age, in relation to the Large White Butterfly,Pieris brassicaeL.

SUMMARYComparison of summer, winter and spring-grown cabbage showed that carotene synthesis differed considerably. Spring-grown cabbage was found to produce a peak of carotenoids during the first week of growth, and this decreased after one month. In comparison, winter-grown cabbage was still producing more carotenoids after 1 month and came to a peak of carotenoid production between 1 and 2 months. The winter-grown cabbage plants were maintained for 12 months and it was found that oxidative processes occurred at a later date than in spring- and summer-grown plants. It is shown that total carotenoids and interconversions of carotenoids are a useful indication of the metabolic processes, including oxidation and degradation of carotenoids, occurring in maturing and senescing plants.The effect of variation of the vitamin A potent carotenoids in the cabbage, and the increased spring production of carotenoids in cabbage, are discussed in relation to the life style of P.brassicae.

THE EFFECT OF CAFFEIG ACID ON THE EPINASTIC CURVATURE OF ISOLATED PETIOLES OF COLEUS SP. IN COMPARISON WITH THE EFFECT OF GIBBERELLIC ACID AND INDOLEACETIC ACID

The isolated petioles of Coleus show a distinct dependence on indoleacetic acid in the development of the epinastic curvature, in aqueous medium. Under the same experimental conditions gibberellic acid shows no effect or an inhibition only. Caffeic acid tested in concentrations between 10−11 and 10−3 evoked varying responses. In winter-grown plants the curvature vs. concentration curve shows two small maxima, which are not evident in the response of summer-grown plants. The interaction of indoleacetic acid and caffeic acid is tested and discussed in elation with the question of the endogenous auxin in Cole us.

The riboflavin content of poultry feeding stuffs

A suitable method of fluorimetric determination of riboflavin was developed, and riboflavin in various poultry feeding stuffs was determined by its use.Riboflavin was determined in fodder plants, vegetable refuse and wild plants. The influence of seasonal changes and of different stages of growth on the riboflavin content in fodder plants was investigated. Summer-grown plants contain more riboflavin than those grown in the rainy winter season. The riboflavin content of the plants declines in the course of their growth.