Inadaptive changes in pH with Zn‐stress tolerance in some cultivars of cotton and peanut

The effects of Zn‐stress on pH of the nutrient medium and the occurrence of Zn deficiency symptoms were examined in 12 cotton and 10 peanut cultivars widely grown in several parts of India. It was found that many of the cotton cultivars were able to reduce the pH, but however unable to recover from Zn deficiency. In contrast, all the peanut cultivars tested did not develop Zn‐chlorosis when subjected to Zn‐stress, although the pH reduction was less significant. The study with these crop cultivars revealed that Zn‐stress tolerance response was not related to pH changes in general. The mechanism by which the peanut cultivars made Zn available and thus averted the onset of Zn‐chlorosis was therefore not adaptive to the changes in pH. This feature appeared to be different from the pattern of correlative pH reduction and recovery from Fe‐chlorosis observed in several Fe‐stress tolerant crop cultivars.     

Phenylalanine ammonia‐lyase activity and ortho‐diphenolic content with regard to boron nutrition in sunflower leaves.

Homogenates were prepared from the leaves of hydroponically cultivated sunflower (Helianthus annuus, L.) under deficient, normal and toxic B conditions and the phenylalanine ammonia‐lyase activity together with the ortho‐diphenolic and micronutrient content were measured every week from one month to flowering

The restoration of enzymatic activity on the exogenous addition of borate “in vivo”; was also studied.

Both B toxicity and deficiency resulted in increased phenylalanine ammonia‐lyase activity in the homogenates

The toxicity effect was early and sustained and the deficiency effect late and transitory. “In vitro”; borate addition to the reaction mixture did not significantly change the phenylalanine‐ammonia‐lyase activity in the homogenates.

There was no statistical correlation between the phenylalanine‐ammonia‐lyase activity and any micronutrient content in leaves.

A high accumulation of ortho‐diphenolics appeared in B‐deficient leaves only after 28 days of differential culture and may be responsible for the drop in phenylalanine‐ammonia‐lyase activity noted at this time.     

Estimation of sulfate and amino acid sulfur in plant material by X‐ray spectrometry

Abstract

The SKα shift between the valences of sulfur has been used to determine by X‐ray spectrometry the two main forms of sulfur present in plant material, viz: oxidised S (S⁶⁺) and covalently bonded sulfur (S^c). S⁶⁺ and S^c were shown to correlate closely with sulfate, as determined by reduction with hydriodic acid, and cysteine+methionine S, respectively. The method is rapid and reliable provided the X‐ray spectrometer is stable and has high reproducibility in goniometer setting. The use of S⁶⁺ and S^c is recommended as an alternative to chemical methods for assessing the sulfur status of crops and the sulfur amino acid content of diets.     

Photosynthesis and metabolic changes in leaves of rapeseed grown under long‐term sulfate deprivation 1

The effect of prolonged sulfur (S) deficiency on photosynthesis and S‐containing compounds in leaves of rapeseed (Brassica napus L.) plants, grown in nutrient solution, was studied under greenhouse conditions. The rate of photosynthetic activity and stomatal conductance of water and CO₂ in treated plants decreased significantly after 3 months of treatment. The total chlorophyll content decreased after one month of S deprivation, after which it remained constant. The total S. content and both the water‐soluble and non‐protein soluble S fractions in the leaves showed a marked decrease. Whereas, the total protein soluble S remained unaffected during the period of observation. In the treated plants, the content of two major S compounds, e.g., cysteine and glutathione, were as a result of deprivation, although in the control it showed a trend to increase. Sulfur deficiency also decreased appreciably the activity of ATP sulfurylase. After the three‐month period of S deprivation, this enzymatic activity was about four times lower than that in the control plants. The data reported in this paper suggested that plants grown under S deficiency were capable of adjusting their S metabolism to maintain a sufficient protein and glutathione synthesis by lowering their photosynthetic activity.     

Effect of moist‐incubation and microbial inhibition on changes in DTPA‐extractable Mn

Abstract

Effect of incubation and microbial inhibition at field capacity level on changes in DTPA‐extractable Mn in acidic, neutral, and alkaline soils was examined. Incubation decreased and microbial inhibition increased the level of Mn in soils with high pH (>5.7) and high microbial activity. The change was apparently partially associated with microbes since the level of Mn did not change in soils with low microbial activity and/or low pH.     

Effect of peduncle‐perfused nitrogen,sucrose, and growth regulators on barley and wheat amino acid composition

Abstract

Nitrogen (N) or growth regulator application to small grain cereals near anthesis has been demonstrated to alter grain fill and grain yield, the protein yield and nutritional quality may also be modified by these management factors. The objective of this study was to determine whether delivery of N, growth regulator, or sucrose solutions into greenhouse‐grown barley (Hordeurn vulgare L. cv. Leger) or wheat (Triticum aestivum L. cv. Katepwa), plants through peduncle perfusion altered the amino acid composition of the grain. The following treatments were tested: N (25 and 50 mM), chlormequat (30 μM), ethephon (15 μM), N + chlormequat, N + ethephon, detillering + N, sucrose (250 mM), distilled water check, and non‐perfused check. Perfusion lasted 30 d beginning 5 to 8 d after spike emergence. Addition of N via peduncle perfusion increased protein concentrations and concentrations of all amino acids in both barley and wheat when expressed in terms of grain dry matter. Protein yield and lysine content were also increased. However, the increase in essential amino acids such as lysine, methionine, threonine, isoleucine, arginine, and leucine was relatively small, and the proportions of these amino acids in the grain protein were actually reduced. The sucrose treatment only affected wheat, increasing lysine concentration and decreasing the total protein concentration. Growth regulators used in this study did not alter protein yield or amino acid composition in either crop.     

Effect of zinc levels on phosphorous and zinc content in sand‐cultured soybeans

Soybeans (Glvcine max L.) cv. “Clark”; were grown in the greenhouse in sand‐filled plastic pots sub‐irrigated with Hoagland No. 1 solution to determine the possible inhibitory effects of Zn on the uptake of P. Zinc rates used were 0.05 (control), 0.25, 0.5 and 2.5 ppm. Yields equalled the control at Zn levels of 0.25 and 0.5 ppm, but plants grown in solutions containing 2.5 ppm Zn were stunted severely. Foliar Zn and P levels differed very little among Zn treatments. Zinc levels were highest and P levels were lowest, however, in the roots and stems of soybeans grown in solutions of 2.5 ppm Zn. Zinc and P uptake was significantly inhibited in the leaves, stems and roots of plants grown at the highest Zn rate. The recycling of wastes containing high Zn content could adversely affect plant growth by a suspected antagonism with P.     

Polyphenol oxidase activity and ortho‐diphenolic content in sunflower leaves in relation to boron nutrition.

Homogenates were prepared from the leaves of hydroponically cultivated sunflowers (Helianthus annuus, L.) under deficient, normal and toxic B conditions and the polyphenol oxidase activity together with the ortho‐diphenolic and micronutrient content was measured every week from one month to flowering.

B deficiency slightly depressed polyphenol oxidase activity and B toxicity decreased it significantly at all times, the response fitting a line versus the logarithm of the B concentration in solution. We found a positive correlation between polyphenol oxidase activity and the B content in leaves.

B action on enzymatic activity seemed not to be caused by direct interaction with substrates as the infiltration of B into deficient leaves did not restore the normal activity

According to our results we suggest that polyphenol oxidase activity may be a valid functional parameter to indicate the nutritional status of B in sunflower plants, if its specificity for B can be demonstrated.

The ortho‐diphenolic content did not change with the B levels used in our experiments. Neither did we find any correlation between enzymatic activity and the o‐diphenolic content of the leaves.     

Impact of tillage and intra-row spacing on cotton yield and quality in wheat–cotton system

Farmers normally practice conventional tillage ((CT), disk plowing, cultivator, rotavator, and leveling) in cotton (Gossypium hirsutum L.) with 15 cm intra-row spacing to avoid risks of poor plant stand and obtain higher yield. However, CT is costly besides it has adverse effects on soil and crop when sown after wheat. Conservation tillage [zero tillage (ZT) or reduced tillage (RT)] with suitable spacing can reduce production cost, increase cotton yield and quality, and it has favorable effects on soil properties. Field experiments were conducted to evaluate cotton response to tillage (ZT, RT, and CT) and intra-row spacing (15.0, 22.5, 30.0, 37.5 cm). Results revealed that RT produced higher bolls plant^?1, boll weight, seed cotton yield, ginning out turn, fiber length and strength than ZT and CT. Mean boll weight, seed cotton yield, earliness, and fiber qualities were optimum at 22.5 cm spacing. Tillage × spacing interaction showed optimum boll weight, earliness, and fiber strength with 15.0–22.5 cm spacing under RT. CT with 22.5 cm spacing also performed better in terms of boll weight and fiber strength; however, 15.0 cm spacing resulted in earlier maturity. RT with 22.5 cm spacing is an alternative to CT for higher yield, earliness, and quality of cotton besides environmental safety.     

Effect of micronutrients on B‐N‐Oxalyl l‐α, β‐diamino propionic acid level and its biosynthesis in Lathyrus Sativus

The detoxification of L. sativus grains by spraying of 0.5 ppm cobalt (nitrate) and 20 ppm molybdehum (ammonium molybdate) salts at the maximun flowering stage ‐ a suggestion based on preliminary findings ‐ has been confirmed in this investigation. Regulatory mechanisms of these micronutrients at the enzymatic level were also studied. On the basis of these observations, the involvement of a hitherto unknown biosynthetic pathway of BOAA cannot be ruled out.     

Acid‐soil‐stress influence on mineral‐ion contents of sorghum leaves and juvenile panicles

Sorghum [Sorghum bicolor (L.) Moench cv RTX430, SC214, SC574, SC599, TAM428, and SC326xSC103] were grown on soils of pH 4.2 or 6.2–6.5. Leaf and nonexserted juvenile panicle tissues were collected at 75 days after planting. Fresh and dry weights were measured and element contents [sulfur (S), phosphorus (P), magnesium (Mg), calcium (Ca), potassium (K), zinc (Zn), iron (Fe), and copper (Cu)] were measured by atomic absorption. Significant cultivar differences in ion concentration (μmol/g dry weight) were found. Juvenile panicles had higher ion concentration (μmol/g dry weight) [S, P, Mg, Ca, K, Zn, and Cu) than leaves. Within leaf tissue, ion concentration (μmol/g dry weight) was correlated with tissue water content (g water/g dry weight).     

Response of no‐tillage and conventional‐tillage cotton to starter fertilization on loess soils

Starter fertilizers have been utilized to improve cotton (Gossypium hirsutum L.) yields, but yield increases have differed with soil type, application method, application rates, and tillage. Starter fertilizer tests were conducted from 1991 through 1993 on a Gigger silt loam (Typic Fragiudalf) in Louisiana and on a Loring silt loam soil (Typic Fragiudalf) in Tennessee to evaluate methods and application rates of 11–37–0 liquid fertilizer for cotton. Treatments were evaluated under conventional‐tillage (CT) and no‐tillage (NT) production systems. Application methods included in‐furrow application at planting (IF), spraying a 4‐inch wide surface band behind the planter (SB), and banding fertilizer two inches to the side and two inches below the seed at planting (2×2). The IF treatments were applied at 1.5, 3.0, and 4.5 gal/A. The SB and 2×2 treatments were applied at 7.5 gal/A. Starter fertilizer treatments were supplemented with broadcast granular fertilizers to achieve a total fertilization rate of 80–40–60 (N‐P₂O₅‐K₂O lb/acre). Starter fertilizer treatments were compared to broadcasting 80–40–60 and 80–0–60. Soil test levels for phosphorus (P) were high on both soil types. In‐furrow applications of 3.0 and 4.5 gal/acre usually reduced plant population for both tillage systems on both soil types. The 1.5 gal/acre IF treatment was less detrimental to stand establishment than the higher IF rates. The effect of starters on plant height varied from year to year. Starter fertilizers usually did not affect early‐season plant height relative to broadcast treatments. In several experiments starter fertilization increased plant height compared to one, but not both, of the broadcast fertilization treatments. High IF rates (3.0 and 4.5 gal/acre) reduced plant height in one experiment. The 2×2 starter fertilizer treatment increased leaf area per plant relative to the broadcast fertilization treatments in two of six experiments on the Gigger soil. Responses for NT and CT studies were similar. In one CT experiment on the Loring soil, the 1.5 gal/acre IF treatment increased leaf area relative to the broadcast treatments. Lint yield responses to starter fertilization were inconsistent. Starter fertilization increased lint yield in one of six experiments on the Gigger soil and in two of six experiments on the Loring soil. Increased yields from starters varied with year and application method, however, the 2×2 and SB treatments tended to provide better responses than IF treatments. Starter fertilizer responses for NT and CT tests were generally similar.     

Effect of N‐form on growth and nutrient content of creeping bentgrass 1

Abstract

The primary nitrogen forms utilized by plants are ammonium and nitrate. Although the importance of nutrients other than nitrogen for proper turfgrass growth is well established, the amounts of these nutrients in the plant tissue in relation to the use of different N‐forms has not been clearly documented. This study was conducted under greenhouse conditions to determine the effect of N‐form and cutting regime on growth, macronutrient, and micronutrient content of creeping bentgrass (Agrostis palustris Huds. ‘Penncross'). Treatments consisted of 100% NO3^? (calcium nitrate), 100% NH₄ ⁺ (ammonium sulfate), and a 50:50 ratio of NH₄ ⁺:NO₃ ^?. Half the turfgrass plants were maintained at a height of 1 cm (cut), while the other half of the plants were not cut until the end of the study (uncut). The uncut 50:50 treatment yielded the highest shoot, verdure, and total plant dry matter, while the uncut NO₃ ^? treatment produced the highest root dry matter. The uncut NH₄ ⁺ treatment yielded the least shoot, root, and total plant dry matter. Plants of the uncut NO₃ ^? treatment had greater accumulation of macronutrients in the shoot and root tissue compared to plants of the NH₄ ⁺ treatment. The uncut NO₃ ^? and 50:50 treatments had higher total accumulation of micronutrients compared to the uncut NH₄ ⁺‐treated plants. The cut NO₃ ^? treatment resulted in the highest macronutrient and micronutrient contents in the root tissue in comparison to other cut treatments. The cut treatments had the highest percentage accumulation of nutrients in the verdure tissue, while the uncut treatments had the highest percentage accumulation of nutrients in the shoot tissue.     

Partitioning of biomass in water‐ and nitrogen‐stressed cotton during pre‐bloom stage

The partitioning of biomass between aboveground parts and roots, and between vegetative and reproductive plant parts plays a major role in determining the ability of cotton (Gossypium hirsutum L.) to produce a crop in a given environment. We evaluated the single and combined effects of water and N supply on the partitioning of biomass in cotton plants exposed to two N supply levels, 0 and 12 mM of N, and two water regimes, well irrigated and water‐stressed at an early reproductive stage. The N treatments began when the third true leaf was visible, while water deficit treatments were imposed over the N treatments when the plants were transferred into controlled‐environment chambers at a leaf area near 0.05 m². Both water deficits and N deficits inhibited total biomass accumulation and its partitioning in cotton. Water deficit alone and N deficit alone inhibited the growth of leaves, petioles, and branches, but did not inhibit growth of the stem and enhanced the accumulation of biomass in squares. When water deficit was superimposed on N deficit, leaf growth was inhibited, although to a lesser extent than when it was the sole stress factor, and the accumulation of biomass in squares was also inhibited. Yet, the dry weight of squares in plants exposed to water and N deficits was greater than that of non‐stressed plants. Water and N deficits, either alone or in combination, did not inhibit the growth of the tap root. Growth of lateral roots was not inhibited either by water deficit alone or in combination with N deficit, but was enhanced when plants were exposed to N deficit alone. Exposure to water deficit alone or in combination with N deficit decreased the shoot:root ratio through the inhibition of shoot growth. Exposure to N deficit alone decreased the shoot:root ratio through the combination of shoot growth inhibition and root growth enhancement.     

Composition of transgenic soybean seeds with higher γ-linolenic acid content is equivalent to that of conventional control

γ-Linolenic acid (GLA) has been used as a general nutraceutical for pharmacologic applications, particularly in the treatment of skin conditions such as eczema. Four transgenic soybean lines that produce GLA at high yields (4.21% of total fatty acids, up to 1002-fold) were generated through the stable insertion of the Delta-6-fatty acid desaturase gene isolated from Borago officinalis into the genome of a conventional soybean cultivar. As part of the safety assessment of genetically engineered crops, the transgenic soybean seeds were compared with their parental soybean seeds (nontransgenic) by applying the principle of substantial equivalence. Compositional analyses were conducted by measuring the fatty acids, proximate analysis (moisture, crude protein, crude fat, carbohydrates, TDF, and ash contents), amino acids, lectins, and trypsin inhibitor activity. The present results showed that the specific transgenic cultivar studied was similar to the conventional control.     

Effect of 2,3,5‐triiodobenzoic acid on calcium level in sunflower plants and incidence of bract necrosis

Experiments were conducted with sunflower (Helianthus annuus, L.) of two inbred lines and eight cultivars grown in the field, in pots in the greenhouse or growth chamber and in nutrient solution. Water solutions of 2,3,5‐triiodobenzoic (TIBA) were sprayed over the top of the plants or added to the nutrient solution TIBA treatment resulted in induction of bract necrosis in some plants, increasing the bract necrosis index with higher TIBA concentration. TIBA had little effect on element concentration in leaves but it decreased the levels of Ca, Mg and B in bracts of plants. At a low TIBA concentration (25 μM) in the nutrient solution, young plants growing in hydroponic solution at a low Ca level, the levels of Ca and Mg of young leaves were decreased but TIBA treatment did not affect significantly the levels of these elements in roots. Since TIBA produces both bract necrosis and lower Ca content in bracts, it is suggested that bract necrosis is a physiological disorder related with lower Ca levels existing in the bracts when plants are grown under stress conditions.     

Influence of split‐applied nitrogen on grain yield and protein content in ten grain sorghum culti‐vars 1

More information on the response of newly developed or introduced grain sorghum cultivare to split‐applied nitrogen (N) in semi‐arid rainfed agriculture is needed. Therefore, the influence of four split‐applied N schedules (100/0, 66/34, 50/50, and 34/66) on six American (SC 283, SC 274, SC 669, B 66181, SC 33, and RTam 428), and four West African (CSm 63, 1S 6704c, 1S 7173c, and 1S 7419c) grain sorghum cultivars was evaluated. The split‐applied N significantly increased grain yield and percent protein in grain sorghum over a one‐time application of N. The increase in yield and protein content varied among varieties and schedules of N application. Varieties SC 574, RTam 428, and Csm 63 at split‐applied schedules of 66/34, 50/50, and 34/66, respectively, gave the highest yield over one‐time application of N. Similar differences in percent protein in grain among cultivars due to split‐applied N were observed.     

The evolution of glucose‐6P‐dehydrogenase and 6P‐gluconate‐dehydrogenase activities and the ortho‐diphenolic content of sunflower leaves cultivated under different boron treatments.

Both enzymatic activities increased under B‐deficient and B‐toxic treatments. The ortho‐diphenolic content did not change with B levels.

Our results suggest that the primary B action on the OPP pathway is at the first enzyme (glucose‐6P‐dehydrogenase) level and that the B effect on 6P‐gluconate‐dehydrogenase is secondary to this. The B action on the enzymatic activities seems not to be caused by any direct interaction with substrates, as B infiltration of B‐deficient culture “in vivo”; seems to result in long term effects on cell structures and/or processes not easily r

In this paper the glucose‐6P‐dehydrogenase and 6P‐gluconate ‐ dehydrogenase activities and ortho‐diphenolic content of hydroponically‐cultivated sunflower‐leaves with moderately deficient, normal and toxic B levels were measured. The change in these parameters during time was considered, together with the restoration of enzymatic activities by means of borate infiltration of deficient and normal leaves. The micronutrient content of the leaves was alsversible by B infiltration of leaves. The positive correlation found between the 6P‐gluconate‐dehydrogenase activity and the Zn content in leaves might be interpretable as and indirect B effect on that activity through modification of Zn content.     

Distribution of cations in leaves of salt‐tolerant and salt‐sensitive lines of sunflower under saline conditions

Two lines of sunflower (Helianthrus annuus L.), a salt‐tolerant Euroflor and a salt‐sensitive SMH‐24, were grown for three weeks in sand culture containing 0 or 150 mol/m³ NaCl in full strength Hoagland nutrient solution. Distribution of cations in the leaves of varying ages was determined. The older leaves of SMH‐24 contained more sodium (Na) in the laminae than the younger leaves at the salt treatment, whereas laminae of leaves of varying ages of Euroflor maintained Na concentration almost uniform. Distribution of potassium (K), calcium (Ca), and magnesium (Mg) in the laminae was strongly age‐dependent in both lines, i.e., the older leaves contained greater concentrations of these cations than did the younger leaves. The lines did not differ in concentrations of the three cations. The older leaves of SMH‐24 had significantly lower K/Na ratios than those of Euroflor, but the lines did not differ in lamina Ca/Na ratios. It is concluded that distribution of K, Ca, and Mg in the leaf laminae is age‐dependent. Salt‐tolerance in sunflower is related to exclusion of Na in the leaf laminae and to maintenance of almost uniform concentrations of this ion in leaves of all ages.     

Catalase peroxidase and IAA‐oxidase activities and O‐diphenolics contents in sunflower leaves grown with different boron levels

Cataiase, peroxidase and IAA‐oxidase activities, so as odiphenolics content in sunflower leaves grown in hydroponics with 4 B levels (0.05; 0.25; 0.5 and 2.0 ppm) were determined. The biochemical assays were made when visual symptons were clearly developed.

Cataiase activity significantly increased in B deficient leaves. Peroxidase, IAA‐oxidase activities and o‐diphenolics content did not significantly change with B levels. The lag period for IAA‐oxidase activity was significantly reduced in B deficient and toxic leaves with respect to the normal ones. These results are in accordance with the hypothesis that one of the B action could be to enhance cataiase activity, the “in vivo” decrease of H₂O₂ levels beeing the cause of the variation in other enzymatic activities related with that substrate.