Neena Khurana

Influence of variable zinc on yield, oil content, and physiology of sunflower

ABSTRACT Sunflower (Helianthus annuus L.) cv. Jwala Mukhi was grown until maturity in refined sand at variable levels of zinc ranging from acute deficiency to excess (0.00065 to 65 mg L−1). Both low (<0.065 mg L−1) and high (>0.065 mg L−1) zinc depressed the growth of sunflower. Foliar symptoms of zinc deficiency appeared on mature middle and old leaves of plants at 0.00065 and 0.0065 mg Zn L−1 as interveinal chlorosis and fading of green color from margins and apices. Later, leaf apices of the affected leaves turned necrotic and dry. Biomass, capitulum size, seed number, seed weight, concentration of chlorophylls a and b, and soluble proteins were maximum at 0.065 mg Zn L−1 (adequate), and were lowered significantly in both deficiency and excess of zinc. The effect of excess zinc (65 mg Zn L−1) on these parameters was more pronounced. An increase in zinc from low (0.00065 mg L−1) to high (65 mg Zn L−1) increased the activity of carbonic anhydrase (up to 6.5 mg Zn L−1) and decreased that of acid phosphatase in sunflower leaves. Zinc deficiency lowered the concentration of zinc and increased that of phosphorus in leaves. In sunflower seeds, the oil content was highest (23.4%) at 0.65 mg Zn L−1 and was reduced more by Zn excess than deficiency. In leaves, tissue Zn concentrations associated with deficiency, threshold of deficiency, threshold of toxicity and toxicity were 20, 30, 190, and 240 μg g−1 on a dry matter basis, respectively.

Zinc Stress–Induced Changes in Biochemical Parameters and Oil Content of Mustard

Abstract An experiment with mustard (Brassica campestris L.) cv T 59 was conducted in a glasshouse under controlled culture conditions to determine the effect of variable zinc (Zn) on biomass, reproductive yield, seed oil, and some aspects of metabolism. Plants were raised in refined sand, and Zn was administered at variable levels ranging from acute deficiency to excess (0.00065 to 65 mg Zn L−1). At 0.00065 mg Zn L−1, symptoms of Zn deficiency were depression in growth, short internodes, chlorosis and necrosis of mature leaves, along with development of purple pigmentation at leaf margins, which later covered the entire lamina. Biomass, economic yield, and seed oil content were highest at 0.065 mg Zn L−1. Zinc at less and more than 0.065 mg Zn L−1 reduced vegetative yield, pod and seed weight, concentration of chlorophyll (a and b), sugars, starch, and protein and elevated the concentration of phenols and activity of acid phosphatase and peroxidase in mustard leaves. The activity of carbonic anhydrase (except at 65 mg Zn L−1), aldolase, and leaf Zn increased with an increase in Zn from deficiency to excess whereas ribonuclease activity was related inversely to Zn supply. In addition to various changes in metabolism of mustard, Zn at higher levels (6.5 and 65 mg Zn L−1) induced symptoms of toxicity on old leaves as interveinal chlorosis, necrosis, and reduction in growth and leaf size. Phosphorus (P) content in leaves decreased concomitantly with an increase in Zn supply from 0.00065 to 65 mg Zn L−1. The values of deficiency, threshold of deficiency, threshold of toxicity, and toxicity in leaves were respectively 18, 25, 200, and 380 µg Zn g−1 dry matter. The activity of aldolase and carbonic anhydrase appear to be reliable biological indicators for evaluating the Zn status of mustard.

Copper Stress Alters Physiology and Deteriorates Seed Quality of Rapeseed

ABSTRACT To observe the effects of deficiency and excess of copper (Cu) on rapeseed (Brassica napus L. cv ‘T44’), plants were raised in refined sand at variable levels of Cu (as copper sulfate): 0.01, 0.1, 0.5, 1, 10, 100, and 200 μM, representing a range from acute deficiency to excess. In rapeseed, excess Cu (200 μM) induced chlorosis on young leaves similar to iron (Fe) deficiency symptoms and appeared earlier (day 30) than symtoms of Cu deficiency (day 40). Foliar symptoms of Cu deficiency (0.01 μM) were initiated on young leaves as interveinal chlorosis, later leading to necrosis. The margins of the affected leaves curled inward and leaves hung down due to loss of turgor. The deficiency (< 1 μM Cu) and excess (100 and 200 μM Cu) of Cu lowered the biomass, pod, and seed yield, concentration of chlorophylls (a and b), Hill reaction activity, activity of catalase and polyphenol oxidase, and increased the activity of ribonuclease and acid phosphatase in leaves. The activity of peroxidase decreased and the concentration of copper in leaves (young and old) and seeds increased with an increase in Cu from low to excess. The accumulation of Cu was greater in old than in young leaves. The seed quality of rapeseed was poor both in deficiency (< 1 μM) and excess (> 1 μM) of Cu, which was reflected in reduction in size and number of pods and seeds, oil content, concentration of protein, carbohydrate fractions (sugars and starch), protein nitrogen (N), and methionine, and increased concentration of phenols and non-protein N in seeds. The values of Cu deficiency, threshold of deficiency, threshold of toxicity, and toxicity were, respectively, 3.8, 6.6, 32, and 54 μg Cu g−1 dry matter in young leaves and 2.2, 5.8, 20, and 28 μg Cu g−1 dry weight in seeds of rapeseed.

Deficiency of manganese is alleviated more by low zinc than low copper in wheat.

Abstract Wheat (Triticum aestivum L.) var. Sonalika was grown in purified sand in complete nutrient solution (normal), deficient manganese (Mn) (0.0055 mg L‐1), deficient copper (Cu) (0.0065 mg L‐1), deficient zinc (Zn) (0.0065 mg L‐1), deficient ?n/deficient Cu, deficient ?n/deficient Zn, deficient Cu/deficient Zn, and deficient ?n/deficient Cu/deficient Zn treatments. The deficiency of Mn decreased the biomass, concentration of Mn, chlorophyll, sugars, Hill reaction activity, acid phosphatase activity, and increased that of peroxidase and polyphenol oxidase. The magnitude of Mn deficiency effects was mitigated to variable extent when Mn was deficient along with deficient Cu and/or deficient Zn. The effects of either Cu or Zn deficiency viz., intensification of foliar symptoms, decrease in biomass, leaf Cu/Zn, seed yield and starch content were increased further in combined deficiency of Cu and Zn. The stimulation in acid phosphatase and decrease in the activity of polyphenol oxidase and carbonic anhydrase in Cu or Zn deficient leaves were further aggravated when both Cu and Zn were deficient together. All these changes reveal a synergism between Cu and Zn in wheat.

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).

Development and Physiological Response of Bittergourd to Boron Level

At some concentrations boron (B) is toxic to bittergourd (Momordica charantia L.). There is a need to determine how bittergourd responds to B concentration. Plants of cv. Jhalari were exposed to 0.003 to 3.3 mg·L−1 of B for 32 days in refined sand. Plants exhibited best growth and total biomass at 0.33 mg·L−1 of B. Visible B deficiency symptoms were observed in plants treated with 0.003 mg·L−1 of B at day 25 manifest as blackening of the growing tip, reduction in size of plants, development of necrotic areas in young leaves, and thickening of the lamina of mature leaves, which later became leathery and eventually brittle. Toxicity symptoms developed at 3.3 mg·L−1 of B and at d 21 margins of old leaves became chlorotic. Exposure to <0.33 and >0.33 mg·L−1 of B reduced total biomass, chlorophyll a and b, carotenoid, and proline contents and activity of catalase and enhanced activities of the antioxidant enzymes peroxidase, superoxidase dismutase, ascorbate peroxidase, and polyphenol oxidase in leaves. Lipid peroxidation decreased, and tissue B concentration increased with an increase in B supplied. Values for deficiency, threshold of deficiency, threshold of toxicity, and toxicity were 5.4, 8, 58, and 120 μg·g−1 dry matter, respectively, in young leaves of bittergourd, which could be helpful in predicting the B status of bittergourd under field conditions.

LOW SULFUR ALTERS BORON METABOLISM OF MUSTARD

Mustard (Brassica campestris L. var. Sarson) was grown in refined sand at three levels, deficient (0.3), normal (30), and excess (300) μM boron, each at low (0.02) and normal [2] mM sulfur. In mustard, dry matter and reproductive yield were highest at combined supply of adequate boron and sulfur. Foliar symptoms of boron deficiency were accentuated by low sulfur. Boron (B) deficiency at normal sulfur (S) reduced flowering, dry matter, pod yield, tissue boron, chlorophyll content, Hill reaction activity, protein and organic labile, and lipid phosphorus fractions, and increased the concentration of inorganic phosphorus, reducing and non-reducing sugars, phenol content, and the activities of peroxidase, acid phosphatase, and ribonuclease. A synergism between boron and sulfur was reflected when boron deficiency effects were accentuated further by combined deficiency of both nutrients. No seeds were formed in boron deficiency regardless of sulfur levels.The foliar symptoms of boron excess were initiated earlier than its deficiency and were more severe at low sulfur levels. At excess boron, the decreases in biomass, pod yield, chlorophyll, and lipid P concentrations were more pronounced at low sulfur level. Also an increase in leaf boron, reducing and non-reducing sugars, phenols, and activity of ribonuclease and peroxidase occurred, indicating a synergistic role of boron and sulfur in mustard.

Impact of Boron Deficiency on Changes in Biochemical Attributes, Yield, and Seed Reserves in Chickpea

To determine the effect of boron (B) deficiency on biomass, reproductive yield, metabolism, and alterations in seed reserves of chickpea (Cicer arietinum L.) cv. ‘13.G‐256,’ plants were grown in refined sand until maturity at deficient (0.033 mg L−1) and adequate (0.33 mg L−1) B, supplied as boric acid (H3BO3). Boron‐deficient plants exhibited visible deficiency symptoms in addition to reduced number of pods and seeds, resulting in lowered biomass and economic yield. Boron deficiency lowered the concentration of B in leaves and seeds, photosynthetic pigments (leaves), Hill reaction activity, starch (in leaves and seeds), and proteins and protein N (in seeds), whereas phenols, sugars (in leaves and seeds), and nonprotein N (in seeds) were elevated. Specific activity of peroxidase (POX) increased in leaves and pod wall and decreased in seeds, while activity of acid phosphate and ribonuclease were stimulated in leaves, seeds, and pod wall in B‐deficient chickpea.

Physiological response of cauliflower in relation to manganese-boron interaction

SummaryCauliflower (Brassica oleracea L. var. botrytis) was grown in refined sand at low (0.0011 mg l−1), normal (0.55 mg l−1) and excess (5.5 mg l−1) Mn, each at three levels of B, deficient (0.0033 mg l−1), normal (0.33 mg H) and excess (3.3 mg l−1). In Mn deficient cauliflowers a deficiency of B accentuated visible symptoms of Mn deficiency and aggravated the Mn deficiency effects i.e. a decrease in dry matter, leaf Mn, sugars, starch, chlorophyll, Hill reaction and specific activity of aldolase and an increase in the concentrations of proline and inorganic phosphorus. In cauliflowers exhibiting B toxicity symptoms under conditions of excess B, excess Mn increased leaf Mn, sugars, nucleic acids, protein P, nucleic acid P, acid-labile P and leaf B. Excess Mn decreased the concentrations of DNA, protein nitrogen, chlorophyll and activities of peroxidase, aldolase and leaf B, leaf Mn in boron deficient cauliflowers.

Response of pigeon pea to variable levels of manganese

Pigeon pea (Cajanus cajan (L.) Millsp.) cv. T21 was grown in refined sand at manganese levels ranging from 0-0011 to 5·5 mg 1−1. At less than 0·055 mg Mn 1−1, growth was depressed. In manganese deficient plants, there was reduction in the area and number of leaves. A reduction in seed yield was observed at low and excess manganese and was optimum at 0·55 mg Mn1−1. Manganese deficient plants showed enhanced levels of peroxidase and ribonuclease activity and caused reduction in chlorophyll content, sugars, Hill activity and activities of catalase, acid phosphatase and aldolase. When manganese supply was low, manganese concentration in leaves decreased and iron, zinc, copper and phosphorus concentrations increased. Values for deficiency, threshold of deficiency and toxicity of manganese in leaves were respectively 25, 39 and 190·5 μg g−1 and in seeds they were 10·6, 12·8 and 18·2 μg g−1 dry matter.