Increase In Leaf Weight Research Articles

Phenotypic Recurrent Selection for Increased Leaf Weight and Decreased Alkaloid Content of Burley Tobacco1

Nine populations were derived in the selection phase of experiments designed to evaluate a recurrent selection scheme in hurley tobacco (Nicotiana tabacum L.). We produced an unselected population of heterozygotes (Co), three populations by recurrent selection for increased weight of green leaves, and five populations by recurrent selection for decreased percent total alkaloids (% TA) of green leaves. Evaluations of the experimental material were made at three locations. The objectives wre to determine the effects of phenotypic recurrent selection on green tobacco and to ascertain the correlated effects of such selection on the yield and alkaloid content of cured tobacco.In response to selection, green leaf weight increased somewhat consistently from C0 to C3 and % TA declined linearly from Co, to C3 The correlated response of cured leaf weight to selection on a green weight basis was a linear increase, averaging 8.1 g per plant per cycle. Percent total alkaloids of cured leaf also declined linearly with successive cycles of selection on a green leaf basis. Five cycles of selection resulted in nearly 23% reduction in percent TA.The genetic correlation coefficient between green leaf weight and percent TA was −0.50 and −0.62 at two locations. This negative relationship may be a limiting factor in practical usage of phenotypic recurrent selection to increase yields without the aid of a selection index.

Daminozide Reduces Stem Elongation of ‘Grand Rapids Forcing’ Leaf Lettuce Grown at High Greenhouse Temperatures1

Abstract Lettuce (Lactuca sativa L.) grown at temperatures greater than 16°C was treated with 5,000, 10,000 or 15,000 ppm succinic acid-2,2-dimethylhydrazide (Daminozide, SADH) at the 4- or 8-leaf stage or both. Plant height was significantly reduced by the 10,000 and 15,000 ppm treatments applied at the 8-leaf or 4- and 8-leaf stage, but the 5,000 ppm treatment was generally ineffective. Total weight was significantly reduced by daminozide, 15,000 ppm being the most effective. Plants treated at the 4-leaf stage had a significantly higher total weight than those treated at the 4- and 8-leaf stage. Both 10,000 and 15,000 ppm daminozide significantly increased leaf weight as a percentage of total weight when applied at the 8-leaf and 4- and 8-leaf stages.

Growth of Vernalized and Nonvernalized Creeping Foxtail1

Herbage dry matter (HDM) accumulation from artificially vernalized (V) plants of ‘Garrison’ creeping foxtail (Alopecurus arundinacea Poir.) was greater than nonvernalized (NV) plants during 46 days in a growth chamber at 27/4 C (day/night). Ratio of reproductive to total shoots was 0.075 with V and 0.004 with NV. Stems and sheaths contributed about 50 and 28% of final HDM of V and NV, respectively. Shoot number was similar between V and NV at the start, but new shoots of NV developed at nearly three times the rate of V. This difference, though, was offset by a slightly increased leaf weight and nearly doubled sheath and stem weight of V over NV. Leaves/shoot were 2.0 and 1.5 on day 6 for V and NV, respectively. The V treatment retained about 0.5 leaf per shoot advantage until day 46 when the values for both were about 3.4 leaves/shoot. Mean relative growth rates (RGR) derived from quadratic functions of HDM over time for V and NV were not significantly different. However RGR of V was slightly higher than NV during the period from 6 to 13 days while RGR values from 13 to 46 days were similar for both treatments.

Morphological and Physiological Effects of Maleic Hydrazide on Tobacco

AbstractTobacco plants (Nicotiana tabacum cv. Burley 21) were cultured in the greenhouse to the 18‐leaf stage. The apical meristem was removed and subsequent axillary bud growth was removed by hand (controls) or axillary bud development was inhibited by application of maleic hydrazide. Compared with the controls, maleic hydrazide treated plants had a decreased stem diameter and stem weight, but an increased leaf weight and leaf weight/area. Plant height and leaf area were the same for both treatments. Maleic hydrazide inhibited translocation of 14C from a single leaf exposed to 14CO2. Respiration was greater than in the controls three days after application of maleic hydrazide, but 9 and 14 days after application there were no differences in respiration between the two treatments. Maleic hydrazide did not affect photosynthetic activity.

Effects of 2-Chloroethylphosphonic Acid on Growth, Plastid Pigments, and Sucrose Translocation in Radish

2-Chloroethylphosphonic acid (CEPA) caused a significant decline in chlorophyll content of radish plant within 5 d of treatment. Such effects were greater when plants were treated at the two- than at the four-leaf stage. In early treated plants, concentration of CEPA increasing from 20 mg/1 progressively increased leaf weight, while decreasing root (radish) weight. A concentration of 10 mg/1, applied at the three-leaf stage, increased leaf and root weights by 27 and 30 per cent respectively in the cultivar ‘Cavalier’. Similar responses were obtained with the cultivar ‘Cherry Belle’. While Cavalier showed a discrete 10 mg/1 optimum, ‘Cherry Belle’ exhibited a range of concentrations (10-40 mg/1) optimal for growth. At relatively high concentrations, early application of CEPA caused inverse changes in sucrose-14C in the leaves and the root, so that decreased retention by leaves was accompanied by increased transport to roots. Low concentrations of CEPA appear promising for growth stimulation in root-crop plants.

Influence of shading treatment on the growth of leaf and root, and sugar accumulation in sugar beet varieties

In order to evaluate the influence of light intensity on the growth of leaf and root in sugar beet varieties, six varieties grown in the field were subjected to shading treatment by cheesecloth at three growing stages (early, middle, and late) as shown in Fig. 1. The results obtained were as follows : 1) The shading at early and middle growing stages brought about the increase in length of leaf, blade and petiole, but the decrease in blade width. These facts suggested that the shading caused the elongation of leaf, which was quite similar to the phenomenon as was often the case with the dense planting. 2) Since root length expressed the length of the noticeable thickened part of the tap root, the larger root length was regarded as the prosperous thickening growth of the lower part of root. The root diameter in individual beet representing the largest diameter of a root will be the yardstick of the thickening growth of the upper part of root. The shading treatments at early and middle growing stages suppressed the thickening growth of the whole root, and the influences of shading were more conspicuous at the lower part of root. However, the interruption of the treatments promoted the thickening growth of this part, and consequently at the end of season the root shape of the treated plant did not show any marked difference as compared with the control. 3) The shading treatment at the early growing stage caused the suppression of the increase in weight of root and leaf, and especially root weight decreased remarkably. After the interruption of the shading, leaf weight was promptly recovered at middle growing stage and it became larger than that of control. These inclinations were marked in varieties such as AJ 4 and Tsukisappu (errect plant type). The shading at middle growing stage caused the increase in leaf weight, but the differences of the increase due to the plant types were not oflserved. 4) The yield type varieties in which leaf weight showed the marked increase by the shading treatment had the lower sugar content at the end of season than that of control. 5) The shading at the late growing stage caused the decrease in sugar content. But the influences on the sugar type varieties (Hon-Iku No. 401 and AJ 4) were not so conspicuous. 6) It was pointed out that the residual effects of the shading such as over-luxuriant growth of leaf and the decline in photosynthetic capacity in shade leaf produced by shading hindered the growth of root.

SHADE TOLERANCE IN TREE SEEDLINGS

SummarySeedlings of five tree species of different shade tolerance were raissed in 100, 44, 17 and 3% of natural daylight. Growth analysis was carried out on data obtained from two harvests during the growing season. The net assimilation rates (E) of the more tolerant species were little higher in 100% daylight than in slight shade (44% daylight), but thereafter E decreased as shade increased. The intolerant species had greatest E in 100% daylight, but this high E fell sharply with increasing shade, and in Populus tremuloides was negative in 3% daylight. Even in this deep shade, however, the intolerant Liriodendron tulipifera had as high a net assimilation rate as the shade‐tolerant species. Decreased E was offset by increased leaf area ratio (leaf area/plant weight), but in contrast to previous studies with herbaceous species, the magnitude of this increase gave no indication of the relative shade tolerance of the different species. In L. tulipifera and Acer rubrum, the increased leaf area ratio resulted from an increase in the proportion of assimilates diverted into leaf production (i.e. increased leaf weight ratio), together with a relatively greater increase in specific leaf area (leaf area/leaf weight). The more tolerant Fagus grandifolia and Quercus rubra showed less increase in specific leaf area, and leaf weight ratio increased only in the deepest shade. No clear‐cut distinction can be drawn between tolerant and intolerant species on the basis of the relative size or efficiency of their photosynthetic systems in low light; factors other than those relating to carbohydrate economy in shade, also play a role.