Nirmala Nautiyal

Molybdenum Stress-Induced Changes in Growth and Yield of Chickpea

Abstract Chickpea (Cicer arietinum L.) cv. K 75 was grown in refined sand at variable molybdenum (Mo), i.e., 0.00001, 0.0001, 0.001, 0.02, 0.2, and 2 mg L−1 supplied as sodium molybdate. The symptoms of excess (2 mg L−1) Mo appeared earlier (d 35) than its deficiency at 0.00001 mg Mo L−1 (d 42). In addition to growth depression, the deficiency symptoms initiated as deep chlorosis of old leaflets (middle portion), spreading to young growth, chlorosis intensified, changed to bleaching, affected leaves dried and withered. In Mo deficient (<0.02 mg Mo L−1) chickpea the flowers produced were less in number, smaller, many failed to open/mature leading to lower seed yield. Excess Mo (2 mg L−1) not only reduced the growth, but also developed chlorosis (iron deficiency type) of young leaves, intensifying with increase in age. Leaves, flowers, and pods were reduced in number and size. Mo stress (< >0.02 mg Mo L−1) decreased the biomass, seed yield (number and weight) and deteriorated the quality of produce. The concentration of Mo in various parts of chickpea increased with an increase in Mo supply. The seed yield was highest at 0.2 mg Mo L−1 whereas the vegetative growth was maximum at 0.02 mg L−1 indicating a higher Mo requirement for economic yield by chickpea. The values of deficiency, threshold of deficiency and threshold of toxicity of Mo were respectively 0.38, 1.2, and 15 µg g−1 in leaves of chickpea.

Influence of Changes in Manganese and Magnesium Supply on Some Aspects of Wheat Physiology

Abstract Wheat (Triticum aestivum L.) cv. UP 2003 was grown in refined sand at three levels of manganese, 0.02 (deficient), 10 (adequate), and 200 (high) μM, each at three levels of magnesium, 0.02 (deficient), 2 (adequate), and 4 (excess) mM. In wheat magnesium deficiency aggravated the effects of low manganese supply namely decreases in dry weight, seed yield, chlorophyll content, Hill reaction activity, contents of DNA and RNA, and activities of ATPase and DNAse. On the other hand, the decrease in the activity of RNAse and increase in that of peroxidase were less pronounced in the combined deficiencies of manganese and magnesium than in manganese deficiency. Excess Mg accentuated the visible symptoms of Mn deficiency. Excess Mg also alleviated the effects of high manganese level by increasing the biomass, contents of chlorophyll, DNA, and RNA, Hill reaction activity, and activities of peroxidase and DNAse and by decreasing further leaf Mn content. It appeared that manganese could not replace the role o...

MOLYBDENUM STRESS AFFECTS VIABILITY AND VIGOR OF WHEAT SEEDS

Wheat (Triticum aestivum L.) cv. Sonalika was grown in refined sand at variable molybdenum (Mo) supply ranging from acute deficiency (0.00002 mg L−1) to excess (10 mg L−1). Deficiency as well as excess of Mo decreased significantly the biomass, grain yield, Mo content in leaves and seeds and activity of nitrate reductase in leaves. The effect of high (>0.02 mg L−1) Mo was more marked than its deficiency on wheat. Low and excess Mo deteriorated the quality of grains by lowering the content of starch, sugars, protein, non-protein, and total nitrogen (N) as well as that of prolamin, glutelin, and globulin fractions of seed proteins and increasing the content of albumin and electrical conductivity (EC) of seed leachate. Molybdenum deficiency and excess both resulted in production of lightweight immature seeds, poor in vigor and germination potential. The post fertilization developmental stages required one tenth of the adequate Mo supply for normal bold seed production in wheat. The values of sufficiency and threshold of toxicity in leaves were 0.13 and 1.15 μ Mo g−1 dry matter of wheat.

Copper stress affects grain filling in rice

Abstract Rice (Oryza sattva L.) cv. Jaya was grown in refined sand at graded levels of copper (Cu) viz. 0.00065, 0.0065, 0.013, 0.065, 0.13, 0.65, and 6.5 mg L‐1. In acute Cu deficiency (0.0065, 0.00065 mg L‐1), the visible foliar symptoms appeared on young leaves as chlorosis changing to necrosis, later affected leaves appeared papery and withered. The biomass and grain yield were highest at 0.065 mg L‐1 and compared to this, the decrease in both parameters was significant at low and high Cu supply. The concentration of Cu in grains increased from 0.4 in acute deficiency to 47.4 ppm at excess Cu. In rice leaves, concentration of sugars and activities of polyphenol oxidase and ascorbic acid oxidase were decreased both by low and excess Cu. Both low and high Cu also retarded the grain formation as well as their quality by decreasing the grain yield and the concentration of starch, sugars and proteins in grains and activities of amylase, invertase and starch phosphorylase at the time of grain filling in see...

Developmental aberrations in seeds of boron deficient sunflower and recovery.

Abstract Sunflower (Helianthus annuus L.) cv. Modern grown in refined sand at deficient (0.033 mg L‐1) boron (B) developed visible symptoms of low B accompanied by marked depression in growth, dry matter, tissue B, flower head size, and seed weight. The B deficient seeds showed a marked decrease in non‐reducing sugars and contents of oil and starch whereas in leaves reducing sugars accumulated. Except for slight increase in leaf B and flower size, resumption of sufficient B (0.33 mg L‐1) to B deficient plants from the day of anthesis could not appreciably alter the growth, dry matter, head size and seed weight of deficient plants. Apart from this, non‐reducing sugar content in seeds increased on resupplying B to deficient plants. A significant decrease in non‐reducing sugars and starch content in B sufficient seeds by withdrawing B from the day of anthesis indicate a specific role of B in production and deposition of reserve in the seeds of sunflower.

Metabolic changes associated with boron-calcium interaction in maize

Maize (Zea mays L.) cv. T42 was grown in refined sand at low (0.1 μM) and normal (30 μu) concentrations of boron each under low (1 mM), normal (4 mM), and excess (8 mM) supply of calcium. Visible symptoms of boron deficiency which appeared first, were accentuated by calcium deficiency and were least evident when calcium was added in excess. The yield was maximum at normal levels of boron and calcium and was the lowest under boron and calcium deficiency. In maize leaves when both calcium and boron were deficient together the activity of starch phosphorylase increased markedly and that of ribonuclease and polyphenol oxidase also increased. The increase in the calcium content inhibited the starch phosphorylase activity when boron was deficient. The activity of peroxidase was stimulated under boron deficiency at all levels of calcium and that of ATPase was depressed significantly when calcium was deficient alone. A decrease in the tissue boron (except in old leaves) and tissue calcium content as well as sugar...

Variations in copper and zinc supply influence growth and activities of some enzymes in maize

Abstract Maize (Zea mays L.) cv. Ganga 2 was grown in refined sand at three levels of copper: deficient (0.00065 mg L-1), adequate (0.065 mg L-1), and excess (6.5 mg L-1), each at three levels, deficient (0.00065 mg L-1), adequate (0.065 mg L-1), and excess (6.5 mg L-1) of zinc. Excess Cu magnified the zinc deficiency effects in maize by lowering further the biomass, the concentration of leaf Zn, activities of carbonic anhydrase, aldolase, and ribonuclease and intensified the visible foliar symptoms of Zn deficiency. The effects of Cu deficiency, low dry weight, the concentration of leaf Cu and activities of cytochrome oxidase and polyphenol oxidase were enhanced by excess Zn. Synergism was observed between combined deficiency of Cu and Zn and Cu or Zn deficiency, because the depression in the parameters characteristic of Cu or Zn deficiency was more pronounced when both Cu and Zn were deficient than when Cu or Zn was deficient. Antagonism was observed in some parameters between combined excess of Cu and ...

Iron‐manganese‐magnesium interaction in cauliflower

Abstract Cauliflower (Brassica oleracea L. var. Botrytis) was grown in refined sand in complete nutrient solution and in solutions deficient each in Fe (0.56 ppm), Mn (0.0055 ppm), Mg (0.5 ppm), Fe‐Mn, Fe‐Mg, Pln‐Mg and Fe‐Mn‐Ng. The magnitude of depression owing to Fe deficiency in dry matter, leaf iron, chlorophyll, starch, protein, RNA and the specific activities of catalase and peroxidase was mitigated, to variable extent, by the combined deficiencies of Fe‐Mg, Fe‐Mn and Fe‐Mn‐Mg. The depression in aldolase. activity in iron deficiency became more pronounced by the combined deficiency of Fe‐Mn and Fe‐Mn‐Mg. Hill activity per mg chlorophyll was least in Mn deficiency, its activity and those of Mg‐ATPase and RNAse uhich were enhanced by Fe deficiency alone, were depressed by the combined deficiencies of Fe‐Mn, Fe‐Mg and Fe‐Mn‐Mg. In the latter two treatments and in Mg deficiency, the pyruvate kinase activity was also depressed.

INDUCTION OF OXIDATIVE STRESS AND ANTIOXIDANT ENZYMES BY EXCESS COBALT IN MUSTARD

This study focuses on induction of oxidative stress and antioxidative defense mechanism on exposure to excess cobalt (Co) in mustard (Brassica campestris L.; cv. ‘T-59’) plants grown in refined sand. Plants were grown for 40 days at normal (0.1 μM) Co. Additional cobalt was supplied from d 41 at 6 levels, i.e., 0.1 (control), 100, 200, 300, 400 and 500 μM as cobalt sulfate. The primary site of Co toxicity was shoots where middle leaves developed interveinal chlorosis after three days of excess cobalt supply (>100 μM). At severity these chlorotic spots became necrotic and affected areas appeared dry and papery, at this stage, growth of the plants were completely checked, the upper part of the stem became dry and hanged down. The toxicity of cobalt at d 46, i.e., six days after metal supply, (DAMS) reduced the dry weight, concentrations of chlorophyll a, b and carotenoids in leaves and tissue Fe with decreased activity of catalase and lipid peroxidation. Enhancement in proline concentration and elevated activities of antioxidant enzymes peroxidase, superoxide dismutase and ascorbate peroxidase were observed in leaves and roots in response to excess Co supply in mustard. Cobalt concentration of mustard in leaves and roots, ranged from 200 to 397 μg g−1 at excess Co as compared to 1.1 to 2.5 μg Co g−1 dry matter in control (0.1 μM Co).

PHYTOTOXIC EFFECTS OF CADMIUM EXPOSURE AND METAL ACCUMULATION IN SUNFLOWER

The phytotoxicity imposed by cadmium (Cd) in sunflower was investigated on biomass, Cd accumulation, superoxide and lipid peroxidation product as well as the activities of superoxide dismutase, catalase and peroxidase. Plants accumulate substantial amount of Cd in different parts, the maximum being in roots, i.e., up to 820 μg g−1 dry matter. Cadmium induced oxidative stress, indicated by increase in lipid peroxidation and superoxide content with increase in metal supply. Under Cd stress, the activities of superoxide dismutase and catalase declined to a greater extent in roots than in leaves. Even though the peroxidase activity increased in leaves, a decreasing trend was observed in root due to Cd stress. The threshold of toxicity (10% growth reduction) and toxicity (33% growth reduction) values of Cd in sunflower were 14 and 72 μg g−1 in leaves, 19 and 90 μg g−1 in stem and 65 and 250 μg g−1 Cd in roots, respectively.