Some studies of the quality of irrigation water and the germination and growth of wheat at different concentrations of boron

Summary The irrigation water in use at the Punjab University New Campus is of good quality except the water of one tubewell which is relatively poor (high-salinity and low-sodium water) and has 0.45 ppm boron. Water with a boron content of upto 3.00 ppm did not affect the germination of the seeds of wheat (Triticum vulgare L. var. Mexi-Pak) and there was some stimulation of the growth of seedlings by an increase in the concentration of boron beyond 0.45 ppm. However, these seedlings, when transplanted to the soils supplied with waters containing different amounts of boron, showed a decrease in their growth at higher concentrations of boron with their ageing, and when these plants were about 100 days old and almost mature, their growth decreased significantly with an increase in the concentration of boron to 2.00 or 3.00 ppm in the water supplied to them. The growth of the plants of Mexi-Pak wheat is inversely related to the boron content of their tissues when it is more than 0.60 ppm. Mexi-Pak wheat is semi-tolerant to boron. re]19750605     

Relative toxicity of arsenite and arsenate on germination and early seedling growth of rice (Oryza sativa L.)

Elevated soil arsenic levels resulting from long-term use of arsenic contaminated ground for irrigation in Bangladesh may inhibit seed germination and seedling establishment of rice, the country's main food crop. A germination study on rice seeds and a short-term toxicity experiment with different concentrations of arsenite and arsenate on rice seedlings were conducted. Percent germination over control decreased significantly with increasing concentrations of arsenite and arsenate. Arsenite was found to be more toxic than arsenate for rice seed germination. There were varietal differences among the test varieties in response to arsenite and arsenate exposure. The performance of the dry season variety Purbachi was the best among the varieties. Germination of Purbachi was not inhibited at all up to 4 mg l^–1 arsenite and 8 mg l^–1 arsenate treatment. Root tolerance index (RTI) and relative shoot height (RSH) for rice seedlings decreased with increasing concentrations of arsenite and arsenate. Reduction of RTI caused by arsenate was higher than that of arsenite. In general, dry season varieties have more tolerance to arsenite or arsenate than the wet season varieties.     

Yield, transpiration and growth of tomatoes under combined excess boron and salinity stress

Boron is essential to growth at low concentrations and limits growth and yield when in excess. Little is known regarding plant response to excess boron (B) and salinity occurring simultaneously. The influences of B and salinity on tomatoes (Lycopersicon esculentum Mill. Cv `5656') were investigated in lysimeters. Salinity levels were 1, 3, 6 and 9 dSm^–1 and B levels were 0.028, 0.185, 0.37, 0.74, 1.11, 1.48 mol m^–3. Excess boron was found to decrease yield and transpiration of tomatoes. This effect was inhibited when plants were exposed to simultaneous B and salinity stresses. Both irrigation water salinity and boron concentration influenced water use of the plants in the same manner as they influenced yield. While yield was found to decrease with increased boron concentration in leaf tissue, increased salinity led to decreased boron accumulation. Yield response was found to correlate better to B concentration in irrigation water and soil solution than to plant tissue B content. A dominant-stress-factor model was assumed and validated. The model applies the principle that when a plant is submitted to conditions of stress caused by B in conjunction with salinity, the more severe stress determines yield. The results of this study have significance in modeling and management of high salinity high boron conditions. Under saline conditions, differences in crop yield and in water use may not be experienced over a significant range of boron concentrations.     

Comparative effects of Glomus mosseae and P fertilizer on foliar mineral composition of Acacia senegal seedlings inoculated with Rhizobium

Summary A factorial experiment with two controlled factors was conducted in the greenhouse with Acacia Senegal seedlings. The substrate was a degraded sandy soil (Dior soil) poor in available P (11 ppm — Olsen). The first controlled factor was soil sterilization, with two levels: (A) sterilized soil; (B) non-sterilized soil. The second factor was fertilization, with six levels: (1) uninoculated control; (2) inoculation with Rhizobium (ORS 1007); (3) inoculation with Glomus mosseae; (4) double inoculation with ORS 1007 and G. mosseae; (5) inoculation with ORS 1007 and 30 ppm phosphorus per plant; (6) inoculation with ORS 1007 and 60 ppm phosphours. The combination of the two factors and their levels led to 12 different plant treatments (A1–A6 and B1–B6). Compared to the control B1, the B5 and B6 treatments containing phosphorus increased: nodule dry weight about 7 times ; leaf dry weight about 4 times ; total N, P and Mg 4–5 times; total K and Ca 3–4 times. The mycorrhizal inoculation had the same positive effect on plant growth and mineral composition but with lower values. Plants inoculated with Rhizobium alone gave the lowest results. The A1 treatment gave lower values than B1. Foliar mineral contents varied within a narrow range (20–30%).     

Morphological changes incitrus associated with relatively high concentrations of paclobutrazol

Progressively higher concentrations of Paclobutrazol-markedly reduced germination of Valencia sweet orange (Citrus sinensis (L.) Osbeck) seed and induced significant changes in the morphology, growth, and development of roots of Valencia seedlings and rough lemon (C. limon (L.) Burm. f.) leaves. Threshold concentrations for significant visible effect to radical change ranged from 10³ to 10⁵ ppm (2.84×10^–4 to 2.84×10^–2 M) (ai). Initial change was readily evident in reduced lateral and fibrous root development at the lower concentrations (10³ ppm). Higher concentrations (10⁵ ppm) resulted in no secondary root formation and progressive basal enlargement terminating in a bulbouslike apex of the primary root. Lack of secondary roots suggests disruption in the pericycle or severe inhibition of meristematic initial cells. Root system changes were not visibly indicated in shoot growth other than strong inhibition of extensions.Mention of a trademark, warranty, proprietary product, or vendor does not constitute a guarantee by the U.S. Department of Agriculture and does not imply USDA approval to the exclusion of other products or vendors that may also be suitable.     

Seedling ecology of two miombo woodland trees

The development of seedlings of two miombo trees, Brachystegia spiciformis Benth. and Julbernardia paniculata (Benth.) Troupin, was studied during two growing seasons (December 1989–April 1991) at a Zambian grassland site. Seed germination rates under laboratory and field conditions were not significantly different although germination in the field was delayed by 1–2 weeks due to insufficient rainfall. After one year of storage J. paniculata seed germination had declined from 67% to 17% while germination of B. spiciformis seeds remained at about 83%.Leaf production was confined to the rainy season. Leaf fall occurred during the dry season and in J. paniculata this was followed by shoot die-back during the hot dry period (August–November). Two-thirds of B. spiciformis seedlings experienced shoot die-back but shoot die-back did not necessarily result in seedling mortality. Seedling deaths occurred during the germination period (6–10 weeks after planting) and in the hot dry period (40–50 weeks after planting) during September–November. Survivorship of B. spiciformis seedlings was 74% at the end of the second growing season while this was 46% for J. paniculata.Shoot growth was negligible during the second growing season. In fact mean maximum leaf area of B. spiciformis decreased significantly from 19.7 cm² (SD=5.7) per plant at the end of the first growing season to 13.3 cm² (SD=5.8) at the end of the second growing season (t=3.31, P<0.01). However, root biomass of B. spiciformis seedlings increased 2.8 times during the second growing season.These results suggest that shoot die-back in seedlings of miombo trees is caused by drought and that the slow shoot growth is the result of allocating most of the biomass to root growth during seedling development.     

Amelioration of NaCl Stress by Arginine in Rice Seedlings: Changes in Endogenous Polyamines

Effects of NaCl (0.1 – 0.2 M) alone or in combination with 1 mM arginine on growth and endogenous polyamine (PA) content have been observed in two cultivars of rice differing in NaCl stress tolerance. The germination, seedlings fresh mass and water content decreased with increase in salinity in both the cultivars. This inhibition was partially alleviated by application of arginine. Cv. CSR-27 exhibited relatively better germination than cv. Bas-370 at different salinities. Total PA content increased in both the cultivars under NaCl stress alone and in combination with arginine. Putrescine to spermidine and spermine ratio was higher in NaCl-treated seedlings being more in cv. Bas-370 as compared to cv. CSR-27 and the ratio reversed to almost control level when arginine was applied along with NaCl.     

Amelioration of NaCl stress in Pisum sativum Linn

Activity of endogenous auxins and growth inhibitors, gibberellins and cytokinins was observed in the extracts of seedlings of Pisum sativum under NaCl stress. After 6 days of germination, when Pisum sativum seedlings were subjected to low concentration of NaCl (50 mM) or boron (10 ppm) increased the endogenous growth regulating substances. Higher concentration of NaCl (150 mM) decreased endogenous level of growth regulators, length of the root and shoot, and fresh and dry weights of seedlings, whereas boron increased the parameters except endogenous growth regulators. Mitotic index and some abnormalities were observed in the treated plants. SDS-PAGE banding pattern of Pisum sativum seedlings extracted in tris-glycine and tris-HCl showed that lower concentration of NaCl increased the number of protein bands, while the higher concentration decreased these protein bands. Combination of boron and NaCl (150 mM) caused an increase in total number of protein bands compared with the total number of bands recorded by using NaCl (150 mM) alone.     

Response of Douglas fir seedlings to phosphorus fertilization and influence of temperature on this response

Summary Effects of P fertilizers on growth of Douglas fir (Pseudotsuga menziesii var.menziesii (Mirb.) Franco.) seedlings were examined in pots and nursery beds. In pot experiments levels of P equivalent to 300 kg/ha were adequate for maximum growth over 14–18 weeks and resulted in available soil P levels of 80 ppm after 15 weeks' growth. Maximum growth in pots was obtained with shoot P concentrations of 0.18%–0.20%, with higher values at lower temperatures, but the optimum concentration for one-year old (1-0) nursery seedlings was 0.16% P. Growth of seedlings was greatly restricted at a soil temperature of 5°C and an air temperature of 12°C. At a soil temperature of 10°C and an air temperature of 14°C seedling P requirement was greater than at soil and air temperatures of 20°C.Comparison showed that monammonium phosphate was more effective than calcium superphosphate in stimulating growth in pots and nursery. Triple superphosphate was also effective in the nursery. Diammonium phosphate, potassium dihydrogen phosphate and phosphoric acid had no advantages as P sources in the nursery. Available P levels of 100–130 ppm, in the loamy sand and sandy loam nurseries studied, and needle P concentrations of 0.18%, when sampled in October, were associated with maximum growth of two-year old (2-0) seedlings.P fertilization decreased root/shoot ratio, but did not alter the allometric relationship of shoot to root. Improving P status from a low level increased root growth capacity in 2-0 seedlings and P fertilization of potted seedlings increased dry weight/height ratio. Uptakes per seed bed ha of 236 kg N, 31 kg P, 81 kg K and 73 kg Ca by 2-0 seedlings were comparable with, or greater than, uptake rates of agricultural crops. Recoveries of 6–11% of P from fertilizer were recorded in the nursery.     

Pollution of soil and vegetation in the Thriasian Plain,Greece

Summary The Thriasian Plain near Athens in Greece is a site of concentrated industrial development. Total concentrations of Pb, Cd and extractable SO₄ ^2– in surface soil samples collected from this area, were found to be, respectively, 2–7, 6–34 and 2–20 times higher than those in similar soil samples from parts of the country remote from industrial activity.Total concentrations of Pb, Cd, Zn, Cr and S in samples of olive leaves from the same area were found to be, respectively, 4–40, 3–10, 3–9, 2–6 and 17–21 times higher than those found in samples of olive leaves from rural sites. Leaves of cabbages growing in the area contained between 0.82 and 40 g/g (wet weight) of Pb.Addition of Cd, Ni and Cu to a calcareous potted soil at concentrations of 100, 200 and 200 ppm increased the concentrations of the metals in the needles of Aleppo pine (Pinus halepensis) seedlings to 4.5, 3.5 and 10 ppm, respectively, after 7 months growth in the nursey.     

Changes in Phytohormone Status in Stems and Roots after Decapitation of Pea Seedlings

Experiments were performed on the first and second internodes and 4-cm-long apical segments of main roots of pea (Pisum sativum L.) seedlings, grown in the light and decapitated above the second node on the seventh day after seed germination. Endogenous phytohormones were measured by the enzyme-linked immunosorbent assay during three days after decapitation of seedlings. The IAA level in the internodes decreased 2–3 times on the second day after decapitation of seedlings while the cytokinin level increased 5–6 times for zeatin and zeatin riboside (Z and ZR) and 1.5–2 times for isopentenyl adenine and isopentenyl adenosine (IP and IPA). In contrast to internodes, the IP and IPA contents in the roots of decapitated seedlings did not change, but the levels of Z and ZR increased 1.5–2 times compared to intact plant roots. The IAA level in the apical region of root remained almost unchanged after the removal of shoot apex. It was concluded that the apical meristem of the main root is not the site of the cytokinin response to the auxin signal coming from the stem apex and that a slight accumulation of Z and ZR after decapitation is due to upper zones of the root. There was no difference in the content of gibberellin-like substances between the internodes of intact and decapitated seedlings. However, the content of gibberellins (GA) in the root tip decreased after decapitation of seedling, which suggests an essential role of apical bud in supplying the root with GA and/or intermediates for their biosynthesis.     

盐度和温度对北美海蓬子在厦门海区引种以及生长特性的影响

研究了厦门海区盐度和温度对北美海蓬子 (Salicornia bigelovii )种子萌发和幼苗生长的影响。结果显示, 海蓬子种子对温度变化反应非常敏感, 在15°C时发芽率最高(94%), 但萌发指数最低, 而在20°C时萌发指数最大; 在盐度5 g.L-1时种子具有最高的发芽率和萌发指数, 在盐度50 g.L-1时仍有13.3 %的发芽率, 并且各种盐度处理下逐日萌发指数均能在2天内达到最大。盐度10-20 g.L-1最适宜幼苗生长, 高盐(＞30 g.L-1)具有一定的抑制作用, 主要表现为生长缓慢, 含水量和根系活力下降, 并且根的盐敏感程度大于茎。在不同盐度处理下, 北美海蓬子适应一种新的耐盐机制, 在无盐(0 g.L-1)和高盐(40 g.L-1) 胁迫下, 过氧化氢酶(catalas e, CAT)和过氧化物酶(peroxide, POD)这2种酶蛋白对盐离子效应敏感, 起主要的抗氧化作用; 相反, 生长在适宜盐度范围(10-30 g.L-1)内, 超氧化物歧化酶(superoxide dismutase, SOD)维持较高活性。研究结果表明, 北美海蓬子适宜在沿海滩涂环境条件下生长, 有望作为一种抗盐耐海水蔬菜加以开发和利用, 并进一步在污染海水净化修复中发挥可能的生态功能。     

Effect of salinity on tomato (Lycopersicon esculentum Mill.) during seed germination stage

A study was conducted using ten genetically diverse genotypes along with their 45F₁ (generated by diallel mating) under normal and salt stress conditions. Although, tomato (Lycopersicon esculentum Mill.) is moderately sensitive to salinity but more attention to salinity is yet to be required in the production of tomato. In present study, germination rate, speed of germination, dry weight ratio and Na⁺/K⁺ ratio in root and shoot, were the parameters assayed on three salinity levels; control, 1.0 % NaCl and 3.0 % NaCl with Hoagland’s solution. Increasing salt stress negatively affected growth and development of tomato. When salt concentration increased, germination of tomato seed was reduced and the time needed to complete germination lengthened, root/shoot dry weight ratio was higher and Na⁺ content increased but K⁺ content decreased. Among the varieties, Sel-7 followed by Arka Vikas and crosses involving them as a parent were found to be the more tolerant genotypes in the present study on the basis of studied parameters.     

Fluxes of carbon dioxide and water vapor above paddy fields

Atmospheric fluxes of carbon dioxide and water vapor were measured by the eddy correlation technique over a paddy field in 1989. The carbon dioxide was transported downward during daylight hours due to photosynthesis of the paddy crop. The downward flux of carbon dioxide increased with increasing net radiation. Maximum values of downward flux varied with the growing stage of the paddy crop: ca. 0.3 mg m^–2 s^–1 at early vegetative growth stage and ca. 1.3 mg m^–2 s^–1 at ear formation stage. The daytime totals of downward flux of carbon dioxide also showed seasonal variation reflecting the photosynthetic activity of the paddy crop: ca. 6 g m^–2 at early vegetative growth stage in June and 40 g m^–2 at ear formation stage in September. The seasonal variation of daily totals of carbon dioxide flux shows that carbon dioxide of about 28 t ha^–1 is fixed by the paddy crop from transplanting to harvesting. Taking into account the water use efficiency, the paddy crop requires water in amounts at least 100 times that of carbon dioxide fixed by photosynthesis. It is noted that the correlation coefficients between carbon dioxide, water vapor and vertical wind velocity have constant values under near neutral and free convective regimes.     

The in vitro Germination of Pollen of Setaria sphacelata

The effects of various substances upon germination and tube growth of pollen of Setaria sphacelata were investigated in hanging-drop culture. Both sucrose (0.6–0.7 M) and boron (1–5 ppm, as borate) are essential for germination. Comparable results were obtained with boric acid, sodium tetraborate and tri-n-butyl borate as boron sources, but sodium tetraphenylboron was inhibitory. Good germination and growth were obtained with raffinose and cellobiose, alone or in combination with sucrose (total 0.5 M); 0.25 M rhamnose, lactose and glycerol were without effect, and xylose, galactose and glucose were slightly inhibitory in the presence of 0.25 M sucrose; 0.25 M arabinose, fructose, mannose, sorbose, maltose, mannitol and sorbitol completely inhibited germination, even in the presence of 0.25 M sucrose. IAA and GA (0.01–10 ppm) could not replace or supplement the effects of borate on germination and growth, indicating the pollen to be self-sufficient in this respect. Riboflavin (0.1–10 ppm) and calcium pantothenate (1–100 ppm) stimulated germination and growth, whereas 0.01–10 ppm of thiamine, pyridoxine, nicotinic acid and ascorbic acid were generally without effect. Although copper sulphate, manganese sulphate, zinc sulphate and ammonium molybdate could not replace boric acid, 1.0 ppm of copper, manganese and zinc stimulated germination and growth in the presence of boron. In no instance were tubes found comparable in length to those required for fertilisation in vivo. It was concluded that the pollen probably requires a complex mixture of substances, including sucrose and borate, before this can be achieved in vitro.     

Putrescine Effect on Nitrate Reductase Activity, Organic Nitrogen, Protein, and Growth in Heavy Metal and Salinity Stressed Mustard Seedlings

Putrescine effect on nitrate reductase activity, organic nitrogen and protein contents, and plant growth under Cd or Pb (0.1 – 2 mM) and salinity (5 and 100 mM NaCl) stresses was examined in Indian mustard (Brassica juncea L. cv. RH-30) seedlings. Cd or Pb and salinity inhibited nitrate reductase activity and decreased organic nitrogen and protein contents in leaf tissue. The increased nitrate reductase activity induced by putrescine was correlated with increased organic nitrogen and protein contents and growth of plants.     

Seed germination and seedling growth of Zostera marina L. (eelgrass) in the chesapeake bay

Seed germination and seedling growth of Zostera marina L. were monitored in the Chesapeake Bay in 1979 and 1980. Harvested seeds were placed in small acrylic tubes at several sites representing the salinity range of Z. marina distribution. Seed germination was observed first in late September and continued through May, with peaks in the fall and spring. The majority of seeds that germinated (66%) did so between December and March when water temperatures ranged from 0–10°C. There was no correlation between sites (different salinity regimes) and frequency of germination rates, indicating that salinity was not a major factor in the germination process in this study. Additional information on seed germination was available for seeds collected in 1977 and 1980 and subsequently monitored for germination at only one site. These data were similar to germination frequency recorded in 1979–1980.Seedling growth was measured from individuals collected from an existing Zostera marina bed. Seedlings were collected from November through May, at which time we could no longer distinguish seedlings from existing vegetative stock. Growth was characterized by the increased length of the primary shoot, number of leaves per shoot and numbers of shoots per plant. Seedling growth was slow during the winter months (water temperature ? 10°C) but rapidly increased in the spring (temperatures > 10°C). The size range of the harvested seedlings indicated that seed germination in the field probably occurred from October through April, corroborating evidence from the seed germination experiments.     

Primary and Lateral Root Development of Dark- and Light-Grown Cotton Seedlings under Salinity Stress*

Primary root growth dynamics and lateral root development of dark- and light grown cotton seedlings (Gossypium hirsutum L., cv. Acala SJ-2) were studied under control and salinity stress conditions. The seedlings were grown by two methods: A) in paper-lined, vermiculite-filled beakers with the plants growing between the paper and the glass wall (Gladish and Rost, 1993), and B) in hydroponics after germination and initial growth in germination paper rolls saturated with the treatment solutions (Kent and Läuchli, 1985). After germination, daily primary root elongation rate gradually incrased to a maximum, then gradually declined to close to zero for dark-grown seedlings, or to sustained rates of about 10 mm per day for light-grown control plants. Salinity stress delayed primary root growth and reduced peak elongation rates, without changing the general primary root growth pattern. These results suggest that salinity changed the time-scale, but did not modify the normal developmental sequence. Lateral root growth was more inhibited by salinity than primary root growth. In addition, elongation of lateral roots was more inhibited by salinity than their initiation and emergence. Light exposure of the shoot favored both sustained primary root growth from 7 days after planting, and lateral root emergence and growth. Salinity effects were more severe on seedlings germinated and grown in hydroponics (method B) than on vermiculite-grown plants (method A). These results emphasize the importance of growing conditions for the NaCl-induced effects on cotton root development. In addition, the differential effects of salinity on primary and lateral roots became evident, pointing to diverse control mechanisms for the development of these root types.     

Response of four rice varieties to Rhodobacter capsulatus at seedling stage

The phototrophic purple nonsulphur bacterium (PPNSB) Rhodobacter capsulatus was used to inoculate seedlings of four rice varieties Giza 159, Giza 171, Giza 176 and Giza 181, grown in hydroponic culture with or without nitrogen. After three weeks the seedling growth parameters were measured. Inoculation with R. capsulatus enhanced seedling growth of all rice varieties tested. The response to inoculation as compared to control plants (no nitrogen, no R. capsulatus) were 52% to 75% for shoot height, 47% to 100% for aerial part dry weight, 45% to 78% for aerial part N content, –37% to –9% for maximum root length, –4% to 8% for root system dry weight and 50% to 62% for root N content.