Dry Weight Distribution Research Articles

Influence of Summer Pruning on the Growth Pattern of Vigorous ‘Delicious’ Apple Limbs

Abstract ‘Delicious’/M9 planted in 1974 were unpruned or pruned on 3 July, 3 Aug., or 3 Sept. 1979, and at a comparable time in 1980. In the distal section, total length and dry weight of lateral shoots were greater on vertical than on horizontal limbs. Lateral shoot length and dry weight were decreased in the distal but not affected in the middle and proximal sections by pruning. Pruning and limb orientation had no effect on the distribution of dry weight in the limb sections. Time of pruning had no influence on the distribution of growth in the limb sections.

Growth inhibition and morphological effects of several chemicals in Arabidopsis thaliana (L.) HEYNH

AbstractA plant life‐cycle bioassay using Arabidopsis thaliana (L.) Heynh. was used to evaluate effects of several toxic chemicals. Plants were grown in vermiculite in a hydroponic system, with test chemicals added to the nutrient solution reservoir. Reduction in total biomass followed different patterns with the chemicals tested, and sensitivity increased in the order: fly ash > 2‐(2‐ethoxyethoxy)ethanol (DGME) > dalapon > trichloroacetic acid (TCA) > copper sulfate > bromacil > metribuzin. DGME, TCA and dalapon induced unusual morphological effects in which flower development was altered and pollination prevented. Reduced biomass, altered distribution of plant dry weight among vegetative, reproductive and mature seed, and morphological effects indicate that a plant life‐cycle test is a valuable screening test.

Rootstock and Scion Effects on the Seasonal Distribution of Dry Weight and Carbohydrates in Young Apple Trees

Abstract Carbohydrates were measured in young apple (Malus domestica Borkh.) trees throughout the period of 28 Mar. 1983 to 16 Apr. 1984. Two rootstocks, M.9 (full dwarf) and MMIII (vigorous) and 2 scion cultivars, ‘Redchief and ‘Northern Spy’ were used in the 4 possible combinations. Trees were separated into 5 classes of vegetative tissue and analyzed for starch, sorbitol, and soluble sugars. Dry weights also were measured. Trees of MMIII had a greater dry weight in the above and below ground portions than trees on M.9. Carbohydrate contents followed a similar pattern. ‘Northern Spy’ scions had greater dry weight and carbohydrate content in the above ground portion than ‘Redchief. ‘Redchief had greater dry weight and carbohydrate content in the below ground portion than ‘Northern Spy’. Above ground starch content and below ground sorbitol and soluble sugar content did not follow this pattern.

Time and Severity of Summer Pruning Influences on Young Peach Tree Net Photosynthesis, Transpiration, and Dry Weight Distribution

Abstract Young peach trees 1) trained to a single shoot or 2) allowed to branch, were pruned by removing 50% of current growth at either or both of 2 summer dates. Another group of trees had 0%, 25%, 50%, and 75% shoot growth removed by pruning in midseason. Net photosynthesis (Pn) and transpiration (Tr) were increased within 3 days after pruning at either date. Plants pruned twice at 30-day intervals had a 2nd cycle of increased Pn and Tr, with rates returning to levels of unpruned controls within 24 days. Distribution of water soluble carbohydrates in various plant tissues was not altered by pruning. Pruning at 60 days reduced root starch, whereas pruning again at 90 days increased total root carbohydrate content. Pruning early in the season increased lateral shoot formation, and terminal bud formation was delayed by pruning. Plant dry weight was reduced by all pruning treatments, with delayed pruning and increasing pruning severity resulting in greatest reductions. Distribution of dry weight was not altered substantially by pruning, and a balance of growth was maintained between different plant parts.

The growth and development of pearl millet as affected by plant population

Pearl millet ( Pennisetum americanum (L.) Leeke) was grown at ICRISAT, Hyderabad, India at 20 densities ranging from 50 000 to 400 000 plants ha −1 using a Nelder fan design. Studies were made on the effect of population on the distribution of plant dry weight, leaf area, grain yield and yield components throughout the season. The first effect of increasing population was evident at panicle initiation (<6% final dry weight produced) where dry weight accumulation in the main axis was unaffected but that in the tillers was reduced. Subsequently, the increased plant population resulted in reductions of 77% in total weight per plant, 66% in leaf area per plant and 59% in tiller number per plant at 50% anthesis. The development of green leaf area per plant followed the same trend over the range of populations, so that leaf area index ranged with increasing population from 2.9 to 6.7 at 50% anthesis; severe leaf senescence occurred in the latter part of grain filling. As population increased, the development of tillers terminated earlier in the growth of the plant, resulting in a reduced tiller survival rate and therefore reduced productive head numbers per plant. Grain yield per plant declined owing to the reduced head numbers and also to lower seed numbers per head. Seed size remained largely unchanged. Population influenced plant yield chiefly through the highly responsive yield fraction of tillers, as the yield of the main axis was relatively stable. Grain yield ha −1 increased to a maximum at 150 000 plants ha −1, which was maintained through to 400 000 plants ha −1 due to the large degree of plasticity in productive tiller number per plant.

Within-row Spacing and Dry Weight Distribution in Two Strawberry Cultivars

Abstract The strawberry (Fragaria X ananassa L.) ‘Midway’ and ‘Guardian’ were grown runnerless at several within-row spacings (8-47 cm). The proportion of dry matter allocated to fruit was negatively correlated with spacing distance for ‘Guardian’ (r = 0.68), but positively correlated for ‘Midway’ (r = 0.91). Total crown weight was positively associated with plant-spacing distance for ‘Guardian’ (r = 0.88) but not for ‘Midway’ (r = 0.05). Specific leaf weight was positively correlated with spacing for both cultivars.

Year Effects on Partitioning of Dry Matter into Cotton Boll Components1

The distribution of dry weight in cotton boll walls, seeds, and fibers was investigated through the boll developmental period for one flowering date each year in 1979 and 1980. Previous experiments on patterns of fiber development encountered large environmental variation, so this experiment with four diverse cottons was undertaken to measure the effect of years on dry weight distribution into boll components. There was a large difference between years in temperature and moisture, with 1980 being hot and dry. Associated with differences in weather between the years was a large difference in dry weight distribution and boll development. In 1980, cotton matured in 88% of the time, individual boll dry weight was reduced 25%, boll wall dry weight per boll was reduced 17%, seed dry weight per boll was reduced 15%, and fiber dry weight per boll was reduced 41% compared to 1979. In addition, bolls developed in 1980 had fewer but larger seeds and fewer but larger fibers than in 1979. Total lint yield was reduced only 7% in 1980 vs. 1979, so more bolls were produced in 1980. At the individual boll level, the differences between years had the greatest effect on fiber dry weight. The effect on fiber dry weight per boll demonstrated the vulnerability of fiber development to environmental variation.

Rootstock and pruning effects on first season dry weight distribution in delicious apple trees

SummaryRedchief Delicious apple trees on MM. 106 and M.9 rootstocks were left unpruned, dormant headed at planting, or summer headed 12 weeks after planting, to investigate pruning and rootstock effects on dry weight distribution between roots and shoots during the first growing season. Dormant heading stimulated new shoot dry weight and reduced new root dry weight during the first six weeks after planting. However, by 12 weeks differences in new root dry weight and new shoot dry weight were insignificant. Summer heading resulted in a significant increase in new shoot growth and decrease in new root growth. This caused the root/shoot ratio in headed trees to return to the unpruned value within six weeks after summer heading. New root growth was reduced over a longer time by dormant heading trees on MM. 106 than those on M.9. New shoot growth was increased longer in trees on M.9. Allometric constants (K) of new shoot growth relative to new root growth were significantly changed by dormant heading with both...

Relation between photosynthetic starch formation and dry-weight partitioning between the shoot and root

The possible relationship of partitioning of photosynthate between starch and sucrose to the distribution of dry weight between the shoot and root was examined in relation to genetic variation and plant nutritional status. Soybean (Glycine max (L.) Merr.), tobacco (Nicotiana tabacum L.), and red-beet (Beta vulgaris L.) seedlings had low relative root weights and accumulated high levels of leaf starch, whereas the reverse was true for wheat (Triticum aestivum L.) seedlings. A similar relationship between starch formation and relative root weight was observed in comparisons among six peanut (Arachis hypogea L.) cultivars and with 'Ransom' soybean and two peanut cultivars exposed to a variety of nutritional treatments. The results suggested that carbon partitioned into leaf starch was preferentially utilized for growth of shoots at night. The postulate was supported by diurnal dry-weight changes of various parts of 'Ransom' soybean plants. Stems and expanding leaves increased in dry weight at about the same rate both during the day and night, whereas roots increased in dry weight during the day but during the night lost about 50% of the dry weight gain. Hence, of the total carbohydrate received by roots over a 24-h period, relatively more material was apparently obtained during the day. Overall, the results suggested that partitioning of carbon between starch and sucrose in the leaf may be one of the factors that affects the growth of shoots relative to roots.

Influence of Summer Pruning and Tree Orientation on Net Photosynthesis, Transpiration, Shoot Growth, and Dry-weight Distribution in Young Apple Trees1

Abstract Young, actively growing, container-grown Malling Merton (MM) 106 apple trees (Malus domestica Borkh.), trained to a single shoot in a greenhouse, were oriented at vertical, 45° from vertical (45°), 90° from vertical (90°), or 90° from vertical and rotated at 1 rpm (90° rotated), and summer-pruned to remove none or 50% of 70.0-cm shoots. Orientation in a nonvertical position and summer pruning delayed a decline in net photosynthesis (Pn) exhibited by vertical unpruned trees. Pruning but not orientation increased total shoot growth, shoot number, and the number and total area of leaves of subsequent growth, but decreased average leaf size. Within 1 week after orientation, unpruned trees at 45° or 90° showed a decline of terminal shoot growth. However, 60 days after pruning a delayed growth of axillary shoots along the tree axis resulted in no difference in total shoot growth, leaf area, or leaf number on subsequent growth compared to vertical unpruned trees. Orientation at 45° and 90° increased the dry-weight root:shoot ratio and induced rootsuckers. Pruning decreased the root dry weight in all tree orientations. Rotation of unpruned trees increased apical growth, axillary shoot numbers, and dry weight of subsequent growth, and decreased root growth compared to unrotated trees.

Zinc in subterranean clover (Trifolium subterraneum L. cv. Seaton Park). I. Effects of zinc supply on distribution of zinc and dry weight among plant parts

Effects of zinc supply on the distribution of zinc and dry weight among plant parts were examined during the first 55 days of vegetative development of Seaton Park subterranean clover grown in a zinc-deficient soil in a glasshouse. Symptoms of zinc deficiency first appeared in young trifoliate leaves. Zinc deficiency decreased the expansion of blades and petioles, delayed the development of leaves and lateral branches, depressed dry weights of roots and shoots, and increased the proportion of plant dry weight in roots and leaf blades. In each treatment and at each harvest, zinc concentrations varied widely amongst plant parts and with their physiological age. Plant parts also differed widely in the response of their dry matter and zinc concentrations to both zinc treatment and harvest time. It is suggested that these complex relationships explain why plant samples consisting of composite plant parts are not suitable for diagnosis of zinc deficiency. In the present experiment, zinc concentration in whole shoots was unsatisfactory for diagnosing zinc deficiency since concentrations were higher in young, zinc-deficient plants than in older, zinc-adequate plants. In young leaf blades of the same physiological age, zinc concentrations showed reasonably constant relationships with plant growth throughout the entire experiment. However, they varied two- to three-fold in leaves of different ages from the same plants. The results show the importance for diagnosis of zinc deficiency of selecting as a sample a single organ of defined physiological age. The youngest open leaf blade is recommended for diagnosis of zinc deficiency in subterranean clover.

Distribution of dry weight between root and shoot in white clover dependent on N2 fixation or utilizing abundant nitrate nitrogen

Plants of white clover var. Blanca were grown singly in pots in controlled environments, or in small swards in a glasshouse, to determine how their distribution of dry weight between root and shoot was influenced when they were dependent on N2 fixation in their root nodules or when they lacked nodules but utilized an abundant supply of nitrate nitrogen. In single plants and in swards, changes in root/shoot ratio with increasing age and plant development were not influenced by the source of nitrogen, but nodulated plants always displayed a higher root/shoot ratio. When nodulated plants were supplied with nitrate nitrogen, root/shoot ratio declined to values intermediate between those of nodulated and of nitrate plants. The results are discussed in relation to the persistence of white clover, and the general level of productivity, in grass-clover swards.

Copper nutrition of subterranean clover (Trifolium subterraneum L. cv. Seaton Park). I. Effects of copper supply on growth and development

Effects of severe and moderate copper deficiency on the development of leaves and lateral branches, on the distribution of dry weight within the plant, and on seed yield of Seaton Park subterranean clover were assessed as part of three glasshouse experiments. Copper deficiency markedly depressed top and root growth without producing any distinctive symptoms. It retarded phasic development by delaying development of leaves and lateral branches, senescence of plant parts, and flowering: it also depressed the proportion of stem plus petiole in plant tops and decreased internode elongation, pollen fertility and the number of burrs and seeds formed. As a result of its effect in delaying flowering, copper deficiency would depress seed production particularly strongly when low soil water supply shortens the growing season. The need for suitable procedures for diagnosing copper deficiency is emphasized by the lack of specific plant symptoms in this species.

Photosynthate Partitioning and Enzymes of Sucrose Metabolism in Sugarbeet Roots

AbstractPopulations of sugarbeet (Beta vulgaris L.) plants that differed in taproot/leaf weight ratio and in photosynthate partitioning between taproots and fibrous roots did not differ in root/shoot ratio as indicated by relative dry weight distribution. Based on the hypothesis that dry weight distribution is influenced by the metabolism of imported sucrose, we examined the relationships between the activity of the enzymes of sucrose metabolism and dry weight distribution as a function of genotype and ontogeny.A decreased specific activity of acid invertase in taproots was associated with increased taproot/fibrous root weight ratio at 21 and at 28 days post‐emergence. Alkaline invertase activity was negatively correlated with taproot/fibrous root weight ratio at 28 days. Sucrose synthetase specific activities of taproots were not correlated with dry matter distribution. Acid invertase may influence photosynthate partitioning between the taproot and fibrous roots via regulation of sucrose levels in the region of fibrous root initiation.

A Study of Inactive Collagenase in Bovine Oral Tissue

A study was made of the distribution and type of inactive collagenase in the bo -vine gingiva, pulp and periodontal membrane of teeth in the stage of mixed dentition. Inactive collagenase was directly extracted with KC1 from tissue, activated with NaSCN, trypsin and both of them, and from the activity of activated collagenase the content of inactive collagenase was calculated.The results obtained were as follows:1. There were two types of inactive collagenase in the bovine gingiva, the pulp and periodontal membrane of unerupted and erupted teeth. One was a complex of collagenase and a 2-macroglobulin, and the other was activated by trypsin but not by NaSCN.2. Distribution of the two types of inactive collagenase in tissue was individually different.3. No relationship was found between the distribution of inactive collagenase and dry tissue weight, the content of RNA, uncollagenous protein and collagen in each tissue.4. A correlationship was found between the distribution of inactive collagenase and the content of DNA in the bovine gingiva, the pulp of unerupted and erupted teeth and the periodontalmembrane of unerupted teeth, but not in the periodontal membrane of erupted teeth.5. In tooth eruption, the pulp showed no difference or decrease in the content of inactive collagenase, while the periodontal membrane was increased.

Effects of competition on yield and dry matter distribution in maize

Abstract Timing and intensity of competition, as a function of plant density and other factors, significantly affect grain and total dry matter production in maize. Competition during different stages of growth affects dry weight distribution among different plant fractions. Greater inter-plant competition occurred in hybrids than in inbreds, and in high densities than in low densities, when this was measured as final dry weight per plant. This intraspecific competition began earlier than 6 weeks from planting, the earliest time of thinning included in the trial. The spatial arrangement of planting maize, high density of associated beans, aggressive bean varieties and an earlier bean planting date all reduced maize yields, but showed no significant effect on dry matter distribution. Plant height was reduced by competition. In density trials, yield increased up to 8 × 104 plants/ha in experimental plots. Farm trials confirmed this density response under a range of conditions, and indicated the potential importance of this agronomic practice to increase yields with no major change in cropping system or increased production costs.

Effect of Water Stress on Carbon Assimilation and Distribution in Soybean Plants at Different Stages of Development1

The effects of water stress on carbon dioxide (CO2) exchange rates (CER) and assimilate distribution were studied in chamber‐grown soybean plants (Glycine max (L.) Merr., ‘Fiskeby’) in the vegetative, flowering, and pod‐filling stages of development. When water was withheld, the decrease in CER was correlated with the increase in stomatal resistance at leaf water potentials as low as −21 bars. Under the above conditions, CER and stomatal resistance recovered to predesiccation levels within 24 hours after rewatering. When leaf water potentials were allowed to drop below −21 bars, recovery of CER lagged behind the return of stomatal resistance to predesiccation levels, suggesting that additional factors may be involved. Whole plants were exposed to labeled CO2 at the three different stages of development and the percent distribution of 14C was determined. At leaf water potentials of −15 to −20 bars, plants displayed alterations in 14C distribution among plant parts corresponding to alterations in dry weight distribution. Compared to well‐watered plants, relatively more 14C was found in the roots of water‐stressed plants before the pod‐filling stage. Less 14C was retained in the leaf blades of these plants, but this response was reversed during pod‐filling. Reduction in 14C in nodules was associated with water stress at all growth stages. Percentage of radioactivity increased in leaves and reproductive structures of plants rewatered and exposed to 14CO2 following return of CER to predesiccation levels. Our results suggest that drought decreased CER and altered assimilate distribution, producing growth modifications that favor efficient use of the limited supply of fixed carbon.

Top and Root Relations of Field‐Grown Soybeans1

AbstractField data describing both the top and root growth of soybeans [Glycine max L. (Merr.)] at different morphological stages are very limited. Such quantitative data are essential for analyzing or simulating growth patterns of whole soybean plants.Soybean top and root growth studies were conducted at the Western Iowa Experimental Farm on Ida silt loam soil [fine, silty, mixed (calcareous) mesic family of typic Udorthents]. Plant height, dry matter distribution of above‐ground plant parts, leaf area index, root length, and root dry weight distribution were measured at different physiological stages.Top‐root ratio of soybeans was 3.8 when the plants were in stage V6, and the ratio increased to 9.0 by the time that the plants reached stage V15R2. From the root length and leaf data, the total length of roots required to supply water and nutrients to each m2 leaf area was calculated. These root lengths increased from 630 m/m2 leaf area when the plants were in V6 stage to 1,190 m/m2 at V13R2 stage then decreased to 345 m/m2 at stage V15R2 as the soil dried. Root length in a specific layer decreased whenever soil was drier than —2 bars or volumetric water content was below 16%.Plant height and leaf area were positively correlated (r = 0.95). Most of the leaf area was concentrated in the upper portions of the soybean canopy when leaf area was maximum.

Growth Pattern, Carbon Dioxide Exchange and Dry Weight Distribution in Wheat Growing Under Differing Photosynthetic Environments

Wheat (cv. WW15) was grown as a crop stand in different CO2 concentrations (ambient, ambient plus 200 � 20 vpm CO2, ambient minus 150 � 20 vpm CO2) from germination to maturity in naturally lit growth cabinets under winter or summer light conditions, at 21°C by day and 16°C at night. Ambient CO2 concentration during the daylight hours averaged 280-300 vpm. CO2 level had little effect on phenology of the mainshoot; most of the growth response was through tillering. From data on flag leaves in the winter light experiment, there was no indication of any positive or negative feedback on growth acting through maximum leaf net photosynthesis rate. Leaf area index was increased by CO2 at low light and the related self-shading acted as a negative feedback partially countering the effect due to an enhanced rate of CO2 uptake per unit leaf area. Dark respiratory CO2 loss represented a greater proportion of CO2 uptake in the light for the CO2-depleted crop than for the control crop. But the reciprocal effect was not evident for the enriched crop. Contrary to classical ideas on growth responses to variation of colimiting factors, the growth response to CO2 enrichment was relatively greater under the low radiation than the high radiation regime. The grain was the tissue most flexible in its responsiveness to changes in assimilation under the conditions of the summer experiment. For this crop, for which the grain yield of the control was very high (0.97 kgm-2), response of yield to CO2 enrichment corresponded to 0.25% per vpm.

Canopy Structure and Dry Matter production in Grasses

In order to know the differences of canopy structure and its relationships with dry matter production, productive structure, growth parameters (CGR, LAI, NAR), extinction coefficient (K) and efficiency of solar energy utilization (Eu) were investigated in the primary swards of fourteen varieties of seven grasses (shown in Table 1). The results obtained are summarized as follows: 1. There were little differences in the productive structure of non-photosynthetic system, but the productive structure of photosynthetic system differed considerably among grasses. The grasses could be grouped into 4 different types according to their mode of the vertical distribution of leaf dry weight and leaf area within the canopy. Tall fescue had the greater leaf distribution towards the base of canopy (triangular type); Reed canarygrass and smooth bromegrass had the leaf distribution which was most abundant in the middle layers and became smaller towards the base and the top of canopy (oval type): Orchardgrass and meadow fescue had the relatively uniform leaf distribution over all layers (rectangular type). In timothy and perennial ryegrass the varietal difference was found, namely, one was the table type which had a greater leaf distribution towards the top of canopy, and the other was the oval type. 2. CGR indicated highly significant correlation with NAR, but not correlated with LAI. CGR also correlated significantly with K and Eu. 3. The rectangular type canopy, which was found in orchardgrass and meadow fescue could utilize light energy in a better way than other types. 4. Among grasses, there were definite differences in the LAI absorbing 95% of the incoming light within canopy. This LAI, corresponding to the critical LAI, was also in agreement with the LAI above the layer indicating the highest leaf area density within canopy. 5. The critical LAI correlated with CGR (r=0.746), Eu (r=0.842) and K (r=-0.747). On the other hand, NAR indicated negative significant correlaiton with the ratio of non-productive system to productive system, when the leaf dry weight below 50% light condition was added to non-productive part. Thus, it was concluded that the critical LAI, not mean LAI, played the most significant role in dry matter production under over-luxuriant canopy.