Search Results
Abbreviations: DW, dry weight; FW, fresh weight; HPS, high pressure sodium; IR, infrared; PPF, photosynthetic photon flux; RGR, relative growth rate. 1 Currently Assistant Professor, Dept. of Horticulture, Forestry, Landscape and Parks, South Dakota
( Petropoullou and Alston, 1998 ) indicates that pollen tube growth can be accelerated under the appropriate high-temperature range, resulting in a reduced travel time of the pollen tube to the ovules. In this study, increased temperature could accelerate pollen
carbon from the atmosphere to drive photosynthetic carbohydrate production, which supports virtually all aspects of plant growth while a large portion of the fixed carbon is respired from aboveground and belowground components ( Taiz and Zeiger, 2010
sunlight, wind, and temperature extremes, which increase crop evapotranspiration. Successful field establishment depends on how quickly plants can recover water uptake capacity to support transpiration demand for normal growth. Water stress increases
Nitrogen is a major nutrient element that is required in large quantity by plants including turfgrasses to maintain active cell growth. However, reducing N fertility is often recommended in turfgrass management to prevent excessive shoot growth or
is lost faster than on flat land, and irrigation is difficult. High temperatures and drought in summer in southern China negatively affect the growth of oil tea seedlings ( Dong et al., 2017 ). For oil tea, drought stress decreased the photosynthetic
Effects of early spring cultural practices and microclimate manipulation on `Jewel' strawberry (Fragaria ×ananassa Duch.) plant development, carbohydrate reserves, and productivity were measured in the field and under simulated early spring conditions in growth chambers. With traditional winter straw mulching practices of the northeastern and midwestern United States, starch content of overwintering leaves, crowns, and roots in the field declined by 51%, 78% and 69%, respectively, during late winter and early spring. There was also a net loss in root biomass over winter and no new leaf growth before mid-April, suggesting that carbohydrate reserves could be limiting plant performance during the critical early growth and flowering phase in spring. In growth chambers, exposure to CO2 levels between 700 to 1000 mL·L-1 significantly increased photosynthetic rates of overwintering and spring leaves compared to ambient CO2 levels. Elevated CO2 in growth chambers also accelerated flower development, reduced depletion of starch reserves in roots, and increased starch accumulation in crowns. In the field, early removal of straw and application of spunbonded rowcover accelerated plant development, increased starch accumulation in the leaves, and increased photosynthetic rates of overwintering and spring leaves. Elevating the CO2 levels under rowcover further increased photosynthetic rates and advanced plant development and starch accumulation, but not significantly above rowcover alone. Carbohydrate losses later in the season during flower development were reduced when rowcover was applied in early spring. Total fruit yield was as much as 48% higher for plants under rowcover in early spring than those that had no cover and an additional 9% higher when CO2 was elevated. Yield improvements were attributed mostly to an increase in the number of marketable secondary and tertiary fruit than to an increase in mean fruit size. The economics of rowcover use is favorable if the material is reused. The added expense of CO2 gas and the resulting marginal gains would not make field CO2 enrichment an economically viable practice for strawberry growers using the method herein.
The growth and development of Anthurium andraeanum Andre cv. Kaumana flower before and after emergence from the subtending leaf base was studied. Eighty days before emergence, the anthurium flower was =0.3 cm long, enclosed by two tightly rolled stipules at the base of the subtending leaf petiole. During the rapid elongation stage of the leaf petiole, the flower (0.8 to 1.0 cm long) entered a period of slow growth 40 to 60 days before flower emergence. After the subtending leaf blade unfurled and had a positive photosynthetic rate, flower growth resumed. Spathe color development started =28 days before emergence when the flower was =50% of the emergence flower length (4.5 cm). At flower emergence, the spathe, excluding the lobes, was =75% red. The lobes did not develop full redness until 7 to 10 days after emergence. Peduncle growth was sigmoidal with the maximum growth rate 21 days after emergence. Spathe growth is characterized by a double sigmoid curve. The young, growing, subtending leaf blade had a negative net photosynthetic rate. Removal of this leaf blade advanced flower emergence by 18 days. The soft green leaf (25 to 30 days after leaf emergence) had a slightly positive measured net photosynthetic rate, and the removal of this leaf resulted in flower emergence 11 days earlier. A mature subtending leaf had the highest measured net photosynthetic rate, and its removal had little effect on flower emergence. The subtending leaf acted as a source of nutrients required for the developing flower. Altering the source-sink relationship by leaf removal accelerated flower emergence, probably by reducing the slow growth phase of the flower.
This experiment was initiated to determine the effects of supplementary lighting of 100 μmol·s-1·m-2 (PAR) in combination with four N rates (100, 200, 300, and 400 mg N/liter) on growth of celery (Apium graveolens L.), lettuce (Luctuca sativa L.), broccoli (Brassica oleracea italica L.), and tomato (Lycopersicon esculentum Mill.) transplants in multicellular trays. Supplementary lighting, as compared with natural light alone, increased shoot dry weight of celery, lettuce, broccoli, and tomato transplants by 22%, 40%, 19%, and 24%, and root dry weight by 97%, 42%, 38%, and 21%, respectively. It also increased the percentage of shoot dry matter of broccoli and tomato, leaf area of lettuce and broccoli, and root: shoot dry weight ratio (RSDWR) of celery and broccoli. Compared with 100 mg N/liter, a N rate of 400 mg·liter-1 increased the shoot dry weight of celery, lettuce, broccoli, and tomato transplants by 37%, 38%, 61%, and 38%, respectively. High N fertilization accelerated shoot growth at the expense of root growth, except for tomato where a 16% increase of root dry weight was observed. High N also reduced percentage of shoot dry matter. Supplementary lighting appears to be a promising technique when used in combination with high N rates to improve the production of high quality transplants, particularly those sown early.
Early fall (September) defoliation and late spring (early June) shading of “off” and “on” pistachio trees were used to test two hypotheses: that 1) fall defoliation would reduce carbohydrate storage sufficiently to suppress spring growth and 2) spring shading would reduce carbohydrate status and increase inflorescence bud abscission. Defoliation suppressed initial leaf area expansion the following spring on current year shoots of “off” but not “on” trees respectively. Suppression of leaf size was correlated with the initial low concentration of carbohydrates in organs of individual branches of the tree. Fruiting and artificial shading in June had more dramatic effects on growth parameters than defoliating. Shading “off” trees for 14 days in early June accelerated abscission of inflorescence buds, reduced dry mass of individual leaves, buds, current year and 1-year-old shoots. Shading also reduced the concentration of total nonstructural carbohydrates (TNC) of these organs in “off” and “on” trees. Fruiting suppressed leaf size and leaf dry mass by 20% and 30% among individual branches of undefoliated and defoliated trees respectively. Low carbohydrate concentrations in individual branches and inflorescence buds following shading were closely correlated with the abscission of inflorescence buds.