Showing papers on "Shading published in 1977"
TL;DR: There was a marked interaction between shading and crop load in their influence on flower bud formation, fruit set and fruit size, which suggests that the effect of shading for one year may partially pre-adapt the tree for such conditions in the following year.
Abstract: SummaryCox’s Orange Pippin apple trees on M.26 rootstock were shaded so as to receive 37, 25 or 11 % of full daylight during the post-blossom growing season in either or both 1970 and 1971 and their flowering and fruit development and yield were compared with those on control trees. Shading reduced fruitlet retention and fruit size and percentage dry matter in the year of shading. It also reduced flower bud formation and had a residual adverse influence on the percentage of flowers which set fruit in the following year. As a consequence of these latter effects, that of shade on yield in the year following shading was at least as great as its effect in the year of shading. There was a marked interaction between shading and crop load in their influence on flower bud formation, fruit set and fruit size, which suggests that the effect of shading for one year may partially pre-adapt the tree for such conditions in the following year. The possible roles of substrate competition and hormonal influences are discu...
78 citations
TL;DR: In this article, the authors suggest that water supply may be a more important factor controlling yield than either solar radiation or plant competition, with the period following pod setting being especially vital.
Abstract: Field experiments, using Vicia faba cvs Herz Freya and/or Maris Bead were made in 1972–5. Population densities were varied and shading treatments were applied. Soil moisture content was monitored throughout. Maximum dry-matter production per plant and per unit area were similar in 1973 and 1974, but lower in 1975. Variations in growth were associated with variations in soil moisture content. When pods began to fill, plants reached maximum total water content and root growth ceased.Increasing density enhanced, and shading retarded both leaf senescence and seed maturation. Maximum potential seed yield (5–6 t/ha) in 1974 was obtained at 32plants/m2. In 1975, yields of 7–9 t/ha were obtained at 66 plants/m2, probably as a result of retention of many pods by the plants. Since total dry-matter production was lower in 1975 than in 1974 we conclude that photosynthetic potential did not limit yield in the earlier year.From the patterns of rainfall, soil moisture and plant water content, we suggest that water supply may be a more important factor controlling yield than either solar radiation or plant competition, with the period following pod setting being especially vital. At this time plant water requirement may often be in excess of supply.
76 citations
TL;DR: Fruits grown under shade had less dry matter and starch per unit fresh weight and lower rates of ethylene and CO2 production per unit weight at harvest, but samples harvested at different dates showed no evidence of any marked shift in the onset of the respiration climacteric.
Abstract: SummaryCox’s Orange Pippin apple trees on M.26 rootstock were shaded so as to receive 37, 25 or 11% of full daylight during the post-blossom growing season in either or both of 1970 and 1971, and the growth, composition and quality of their fruits at harvest and after storage compared with those from control trees. In 1972 a separate experiment using Cox on M.9 involved shading to 34 or 13% of full daylight. Shading reduced fruit size, through reductions of cell size and the number of cells per fruit, fruit colour and the degree of skin cracking and russeting. Fruits grown under shade had less dry matter and starch per unit fresh weight and lower rates of ethylene and CO2 production per unit weight at harvest, but samples harvested at different dates showed no evidence of any marked shift in the onset of the respiration climacteric. The incidence of core flush and shrivelling in storage was increased by shading during the growing season. There was no evidence that the concentrations of N, P, K, Ca or Mg d...
71 citations
TL;DR: In this paper, the potential acetylene reducing activity per plant varied little from year to year and environmental factors such as water supply exerted increasing effects on activity, such as shading prolonged activity and delayed nodule senescence.
Abstract: N fixation data, estimated by the acetylene reduction technique and by total N content are given for the field experiments reported by Sprent, Bradford & Norton (1977).Maximum potential acetylene reducing activity per plant varied little from year to year. At low population densities a maximum rate of activity was observed shortly after flowering. As density increased this maximum became less pronounced and environmental factors (such as water supply) exerted increasing effects on activity. Shading prolonged activity and delayed nodule senescence.Total plant N continued to increase almost to seed maturation. As plants aged, the acetylene reduction technique progressively underestimated N accumulation. Maximum Nfixed/ha/year was over 600 kg. Itis concluded that the potential for N fixation in this crop is sufficient to sustain high yields.
67 citations
53 citations
TL;DR: Cox’s Orange Pippin apple trees on M.26 rootstock were shaded so as to receive 37, 25 or 11 % of full daylight during the post-blossom growing season in either or both 1970 and 1971 and their growth compared with that of control trees.
Abstract: SummaryCox’s Orange Pippin apple trees on M.26 rootstock were shaded so as to receive 37, 25 or 11 % of full daylight during the post-blossom growing season in either or both 1970 and 1971 and their growth compared with that of control trees. Shading had direct and also residual effects, the latter in the year following treatment. It reduced the number and weight of new shoots, the fresh weight per unit length of shoot, girth increment and leaf thickness and weight per unit area, but increased the concentrations of K and Mg in the leaves. Residual effects included a reduction in the number of shoots but increases in girth increment, in weight per unit length of shoot and in leaf dry weight per unit area and per unit fresh weight. These latter results are thought to be a consequence of reduced competition for assimilates as a result of a drastic residual effect on the number of fruits carried. In the year after shading the concentrations of N, P, Mg and Ca in the leaves were reduced and that of K increased.
41 citations
TL;DR: The ability of this wintergreen species to increase in weight during the winter when grown in heavy shade confers a considerable selective advantage in many woodland situations.
Abstract: (1) Populations of Oxalis acetosella from different environments show marked variations in such features as height, leaflet width and chlorophyll content. (2) Genetic differences between two Salop populations, one from a woodland streamside and another from a montane sheep-grazing on the Long Mynd, were demonstrated when clones from both were brought into cultivation. Mean leaflet widths of the streamside population remained larger than those from the Long Mynd when growing under the same conditions. (3) In investigations of phenotypic plasticity plants were grown in the open and in cold frames which at midday received approximately 70%. (A), 27% (B), and 6% (C) of the light available to the open treatment. Leaflet widths of plants of both populations grown under high light intensities were narrower and plants were of lower specific leaf area (SLA) than those of Treatment B, while the most heavily shaded leaves (C) had the highest SLA and the largest chlorophyll content on a fresh weight basis. Root/shoot ratios were lowest in the most heavily shaded plants. Strongly lit plants produced relatively few seeds, plants of Treatment C formed a moderate amount of seed and plants of Treatment B fruited very abundantly. (4) Shade leaves of Oxalis are wider, thinner, of lower stomatal frequency, and with better developed funnel-cells than sun leaves. (5) The leaves of well illuminated plants senesce far earlier than those grown in shade. The ability of this wintergreen species to increase in weight during the winter when grown in heavy shade confers a considerable selective advantage in many woodland situations. (6) A growth cabinet experiment, in which heavily shaded plants were grown at the same temperature but at lower relative humidity than unshaded plants, showed that the higher SLA characteristic of heavily shaded plants is a direct response to shading.
40 citations
TL;DR: The poor seedling performance of leucaena in competition with other species does not appear to be due to a failure to tolerate shade, and in this respect it appears to be better than some other tropical pasture legumes.
Abstract: The growth of seedlings of the forage shrub legume Leucaena leucocephala cv. Cunningham was studied at three levels of shading (100, 57 and 35 per cent relative photosynthetic quantum flux) in a glasshouse. An additional treatment investigated the response of unshaded plants to nitrogen fertilizer applied twice weekly. Shading reduced total plant weight (3.83, 3.20, 2.46g), increased the shoot/root ratio, increased internode length and plant height. However, with increasing shade there was a linear increase in leaf area, and relative growth rate (RGR) of shoots was affected little. RGR of the roots declined sharply from 0.62 to 0.51g g -1 week-1 with shading. Only at the lowest luminance was the dry matter per cent of shoots decreased (32 per cent to 28 per cent). Leaves were larger and thinner in the shaded treatments but rate of leaf appearance was unaffected. Added nitrogen (= 225 kg N ha-1) increased uptake of nitrogen (by 68 per cent), nitrogen concentration (59 per cent) and leaf weight (24 per cent) but had no significant effect on plant height, number of leaves, RGR, or dry matter per cent of shoots. The poor seedling performance of leucaena in competition with other species does not appear to be due to a failure to tolerate shade. In this respect it appears to be better than some other tropical pasture legumes.
16 citations
TL;DR: It was considered that low light intensity during monsoon season was an important constraint for higher productivity since yields as low as 3.2 to 4.4 tons/ha were recorded with varieties which yielded 8 to 10 tons/ ha under high light intensity conditions as in rabi.
Abstract: The effect of low light intensity (40 to 50% of natural light) at different growth stages and subsequent exposure to natural light was assessed on growth and productivity in 2 genotypes during kharif and 3 during rabi under 2 N levels. The dry matter accumulation was affected under shading at all stages, which was critical from primordial initiation (PI) onwards. The expression of panicle number appears to be a function of the environment particularly the light intensity within 26 to 39°C range of mean maximum temperatures. The grains/panicle were also reduced by shading from PI onwards. The yields were progressively reduced with low light intensity appearing in succession at different growth stages, particularly more critical during ripening phase. It was considered that low light intensity during monsoon season was an important constraint for higher productivity since yields as low as 3.2 to 4.4 tons/ha were recorded with varieties which yielded 8 to 10 tons/ha under high light intensity conditions as in rabi. re]19751014
10 citations
TL;DR: In this article, the authors presented a detailed description of solar calcimeter designed and fabricated at the Institute for measurement of thermal characteristics of glazing and shading materials, which has been used to evaluate the transmission and shade characteristics of different types of glasses, curtains, venetian blinds and external shading.
Patent•
16 Mar 1977
TL;DR: In this paper, a simple shading correction not only for the main scanning direction but also for the secondary scanning direction is proposed to ensure a high efficiency and simple shading corrections for both directions.
Abstract: PURPOSE:To ensure a high-efficiency and simple shading correction not only for main scanning direction but for secondary scanning direction.
Patent•
21 Feb 1977
TL;DR: In this paper, a simple circuit structure was proposed to reduce shading with simple circuit structures as it occurs in the color TV camera, which reduced the shading in the TV camera image.
Abstract: PURPOSE:To reduce shading with simple circuit structure as it occurs in the color TV camera.
Patent•
19 Oct 1977
TL;DR: In this article, the authors proposed to amplify the differences in shading and improve the accuracy of detection by integrating the outputs from and optical sensor, which can amplify the difference in shading.
Abstract: PURPOSE:To amplify the differences in shading and improve the accuracy of detection by integrating the outputs from and optical sensor.
TL;DR: Artificially shaded and unshaded containerized Pinusponderosa Laws, seedlings were planted in the Sacramento Mountains of southern New Mexico on July 29, 1975 and at the end of September no mortality had occurred in either treatment.
Abstract: Artificially shaded and unshaded containerized Pinusponderosa Laws, seedlings were planted in the Sacramento Mountains of southern New Mexico on July 29, 1975. Xylem pressure potential (Pstem) and relative water content (RWC) were measured four times per day from August 1 to 16, 1975. Shading had little effect on RWC but significantly increased Pstem; midafternoon (1530 hours, MDST) increase averaged 2 bars (1 bar = 105 Pa). During the study RWC ranged from 86 to 94% and Pstem ranged from −4 to −10 bars. At the end of September no mortality had occurred in either treatment.
Patent•
22 Nov 1977