Studies in the Nutrition of Apple Rootstocks The Effect on Growth and Mineral Composition of Supplying Iron Through the Leaves

Apple rootstocks were grown with either 0.02 ppm Fe (Fe₀) or5 ppm (Fe₃), to give very chlorotic or dark-green plants. Toinvestigate whether iron can be supplied through leaves insteadof roots the shoots of half the plants in each treatment weredipped periodically in solutions of iron. This prevented chlorosisin Fe₀ plants and increased their growth, which did not, however,equal that of Fe₃ plants supplied with iron through the roots.Growth of Fe₃ plants was reduced by dipping. Iron was not translocated from leaves to roots, although theconcentration in leaves was greatly increased by dipping. Dippingreduced the amount of manganese in Fe₀ roots to one-quarterof that in roots of undipped Fe₀ plants. Effects of treatmentson nitrogen, potassium, calcium, magnesium, and copper levelsare also described.     

Salt and Mineral Nutrient Levels in Fruits of Two Strand Species, Cakile maritima and Arctotheca populifolia, with Special Reference to the Effect of Salt on the Germination of Cakile

Nutrient and salt (NaCI) levels were examined in fruits of twostrand species, Cakile maritima and Arctotheca populifolia,collected near Perth, Western Australia. Nutrient levels inseeds of C. maritima and achenes of A. populifolia were relativelyhigh when compared to those in seeds of Australian native speciesor introduced crop plants, despite the very low nutrient statusof the strand habitat. The high levels of organic and essentialinorganic nutrients in seeds would be of especial value in seedlingestablishment. The upper seed of the two-segmented fruit ofCakile was heavier than the lower seed, but both seeds had verysimilar levels of nutrients. Concentrations of N, P, and micronutrientswere very much higher in seeds of Cakile and Arctotheca thanin other parts of the fruit. Cakile leaves had similar levelsof N and P to seeds, but higher levels of micronutrients, especiallyNa and Cl. In Cakile, concentration ratios for Na levels inleaves, silicule and seeds were 359: 74: 1 respectively, thosefor Cl were 200: 30: 1, suggesting very restricted loading ofNa and Cl into the phloem stream destined for fruits, and selectiveuptake by developing embryos. Cakile seeds germinate within their fruit segments, and levelsof NaCl in recently-matured fruits would be high enough to suppressgermination. The top segment of the fruit had a higher concentrationof NaCl than the bottom, and it is likely that this is responsiblefor the lower germination of seeds within top segments. Theliterature on seed dormancy in Cakile is reviewed briefly, andit is concluded that salt levels in the fruit wall and strandsoil are the major determinants of dormancy in Cakile seeds. Cakile maritima, Arctotheca populifolia, germination, sodium chloride, mineral nutrient levels, micronutrients, macronutrients     

Temperature Controls a Dependence of Barley Plant Growth on Mineral Nutrition Level

The effect of temperature regime on growth and other morphological characteristics of barley plants (Hordeum distichum L., cv. Andrei) as dependent on the level of mineral nutrition was investigated in a controlled experiment. Plants were raised hydroponically at a high (0.22 g/(g day)) and low (0.05 g/(g day)) relative rates of the addition of mineral nutrients (R _A). Mineral nutrients were daily added to the nutrient solutions in exponentially increased amounts to provide steady-state plant growth. At the optimum temperature regime (21/17°C, day/night), the plant relative growth rate (RGR) was proportional to the preset R _A during the entire exponential period. Low R _A led to a decrease in the nitrogen content in plants, plant weight, and respiratory activity, as well as to the increase in the relative root weight. Biomass accumulation at lowered temperature regime (13/8°C) and a high R _A was 1.8-fold lower than at optimum temperature regime. Although under these conditions, the ratio of respiration to gross photosynthesis reduced threefold due to the decrease in the respiration rate, RGR of plants was equal to 0.11 ± 0.02 g/(g day), which was twice lower than the preset R _A. These pointed to the decrease in plant ability to maintain a certain ratio of photosynthesis to respiration within a day. At a deficiency of mineral nutrition and low temperature, RGR reached the preset R _A. Plants adapted to lowered temperature by a shift of the temperature optimum of their metabolism (heat production) to lower values. As a whole, a low variability of such growth parameters as RGR, C/N, and root to shoot weight ratio at different R _A and lowered temperatures testified to the lessening of growth limitation by the mineral nutrition.__________Translated from Fiziologiya Rastenii, Vol. 52, No. 3, 2005, pp. 384–391.Original Russian Text Copyright © 2005 by Garmash.     

Studies in the Nutrition of Apple Rootstocks: III. Effects of Level of Magnesium Nutrition on Growth, Form and Mineral Composition

One-year rooted shoots of apple M. VII rootstock were grownfor a single season by spraying their roots continuously withnutrient solutions containing <3, 10, 45, and 135 ppm Mg.These treatments respectively produced plants with a severeMg deficiency (Mg₍₀₎), a mild deficiency (Mg₍₁₎), normal foliageand growth (Mg₍₂₎), and a high level of Mg (Mg₍₃₎). The effectof Mg nutrition on the leaves can explain most of the observedeffects on vegetative growth. Depression of growth of Mg₍₁₎)plants was not detected until late in the season although necrosis,typical of Mg deficiency, occurred on the lower leaves by mid-July.This loss of photosynthetic area of leaf was to a large extentcompensated for by increased efficiency of the remaining greenleaves; as the deficiency symptoms progressed, the loss of leaf,and therefore of carbohydrate production, predominated and totalgrowth was affected. The form of the plant was little altered. Symptoms were apparent on leaves of severely deficient Mg₍₀₎plants by late June, and reductions in growth and modificationsin form by August. The poor root systems and thin shoots arelargely attributed to loss of leaf rather than to the low Mgconcentration in these organs. No symptoms of toxicity developed on the Mg₍₃₎ plants althoughby the end of the season the total dry weights were less thanthose of the Mg₍₂₎ controls, and the plants also produced thickershoots. Plant dry weight, and more especially Mg uptake, increasedfrom Mg₍₀₎ to Mg₍₂₎ but above this level the gradient of Mguptake in relation to supply was less steep. The excess Mg takenup at the Mg(j) level led to the relatively lower weights ofthese plants. Much of the excess Mg accumulated in the leaves,especially in the older ones. Mg moved from, or accumulatedin, the lower leaves of the shoot according to the level ofMg supplied to the plants. Thus the shoot apex tended towardsnormality both in the concentration of Mg and in its growth. In general, growth of the plant, and of individual componentparts, governed the uptake of elements other than Mg, althoughmore K, Ca, and Mn and less Fe per unit of plant dry weightaccumulated at the lower levels of Mg than at the higher levels.     

The Effect of Mineral Nutrition on the Distribution of Growth in Lolium perenne

Ramets of Lolium perenne from the same genotypes were grownin nutrient solutions of two concentrations. Additional mineralnutrition increased the rate of production of new tillers, therate of increase in size of tillers and the rate of productionof new roots, but not the rate of growth of individual mainroots. The genotypes differed considerably from each other intheir rates of growth, especially of shoot growth. When thegrowth-rate of the same population of genotypes was alteredby changing the environmental conditions it was found that thelower the mean rate of shoot growth, the greater its coefficientof variation. Variation in the rate of shoot growth, due tomineral nutrition and genetic constitution of the plants growingin a dilute nutrient solution, was accompanied by a similarbut smaller variation in the number of roots.     

Studies in the Nutrition of Apple Rootstocks: IV. The Effect on Growth and Mineral Coomposition of Supplying Magnesium through the Leaves

One-year rooted shoots of M.VII apple rootstock were grown fora single season by spraying their roots continuously with nutrientsolutions containing either < 3 ppmMg(Mg₍₀₎) or 45 ppm(Mg₍₀₎)to give, respectively, potentially very deficient or healthyplants. The new shoots of half the plants in each of these treatmentswere dipped periodically in a 2 per cent solution of MgSO₄.₇H₂O plus ‘wetter’. Mg₍₀₎ undipped plants developed severe symptoms of Mg deficiency,growth was poor, and the shoot/root dry-weight increment ratiowas high; none of these characteristics was found in Mg₍₀₎ dippedplants, whose growth was not appreciably less than that of Mg₍₂₎undipped controls. There was little translocation of Mg from leaves to roots: theconcentration of Mg in roots of Mg(0) dipped plants was as lowas that of the undipped. The large accumulation of Mn and, toa less extent, of Fe in Mg₍₀₎ dipped roots was not apparentlydetrimental to growth. Growth of Mg⁽²⁾ dipped plants was similar to that of the undipped. Dipping had little effect on the chemical composition of leaves,except to raise the concentration of Mg.     

Effect of Temperature on the Growth and Development of Tomato Fruits

Tomato fruits ripened 95, 65, 46 and 42 d after flower openingwhen plants were grown under controlled environmental conditionsat 14, 18, 22 and 26 °C, respectively. A similar responseto temperature was observed when the temperature of individualtrusses was modified while the plants were grown at 20 °C.These data were used to develop a thermal time model for fruitmaturation. However, when buds/fruits were heated at differentstages in their development, the thermal time model proved tobe a poor predictor of the time of ripening. Fruits were moresensitive to elevated temperature in their later stages of maturation.Temperature also affected the rates of fruit growth in volume;these could be adequately described using a Gompertz function.Low temperatures reduced absolute volume growth rates and delayedthe time at which the absolute growth rate became maximal. However,the response of fruit growth to temperature differed when onlythe temperature of the fruits was modified. There was a tendencytowards small parthenocarpic fruits at both high (26 °C)and low (14 °C) temperature regimes which, combined withlow flower numbers and poor fruit set at 26 °C, resultedin low fruit yields. Temperature also affected the shoot drymatter content and partitioning. Copyright 2001 Annals of BotanyCompany Tomato, Lycopersicon esculentum, fruit, growth, ripening, temperature, temperature stress, parthenocarpy     

Shoot Growth and Mineral Composition of Leaves and Fruits of Apple as Affected by Relative Air Humidity

Shoot growth and water consumption of potted Golden Delicious trees were studied under a controlled environment with respect to two lewels of air humidity, soil moisture content, and the availability of nitrogen. In the high-N treatment, high air humidity and high soil moisture content promoted growth; at the low-N level, growth did not respond to the treatments. Water consumption was enhanced at low air humidity but was not afiected by the moisture centent of the soil. In potted fruit&earing Cox's Orange Pippin trees exposed to two levels of air humidity, low humidity reduced shoot growth and, but to a much lower degree, fruit growth. It increased rhe spur-leaf levels of N, Mg, and, for part of the experimental period, K and Ca, but affected hardly the mineral level in fruits. It is concluded that the amount of the minerals reaching the fruit is determined by the relative im-portance of the xylem influx during the first few weeks after fruit set and the phloem influx occurring throughout. It is suggested that the xylem supply of the various minerals does not differ greatly; it is probably the main way for the influx of Ca, but for N, K, Mg, and P the phloem influx is com-pletely dominating.     

Mineral Nutrition and Plant Growth Response to Climate Change

The limiting factor concept has often been used to describeplant growth responses to altered availability of resources.However, even preliminary experiments, where atmospheric CO₂concentrations and solution mineral concentrations were varied,demonstrated that a more complex concept was required to interpretthe potential effects of climate change and mineral availabilityon plant growth. It is proposed that these resources for plantgrowth may be better viewed as simultaneously limiting. Further,in considering the limitation in plant growth to mineral nutritionit is important to consider both the solution concentrationand the total amount of the individual minerals available tothe plant. Sustaining a positive response to increased CO₂ concentration,for example, requires an increase in plant uptake of the totalamount of minerals. Consequently, it is very difficult to predictthe plant growth response to climate change because of the largeuncertainty about mineral availability. On the one hand, increasedCO₂ concentrations should stimulate nitrogen fixation by bothfree-living organisms and symbiotic systems, and improve soilproperties for mineral availability as a result of increasedorganic matter deposition in the soil. On the other hand, increasedtemperature and altered rainfall patterns may result in increasedlosses of soil minerals. Even the direction in the net changein available soil minerals is unclear. Realistic evaluationsof the effects of climate change on plant growth will be challengedto contend with the large uncertainty and complexities in understandingmineral availability and plant mineral nutrition.     

Physiological Studies in Plant Nutrition: XVII. A General Survey of the Free Amino-acids of Barley Leaves as affected by Mineral Nutrition, with Special Reference to Potassium Supply

A survey by means of paper chromatography of the free amino-acidsin barley leaves at different stages of development is described.The plants were grown in sand culture, using a variety of nutrientsolutions, the most important variable being potassium supply.In general, the amino-acid distribution is not greatly affectedby nutritional differences. Potassium deficiency results in much increased contents of theamides, especially asparagine, and reduced amounts of the correspondingacids. Other acids increased under these conditions are serine,leucine, tyrosine, and phenylalanine, but the most characteristicchanges occur in -the basic constituents; lysine and arginineare increased, and an unknown basic substance accumulates verycharacteristically. Accumulation of this substance (probablyan amine) is checked by the presence of either sodium or rubidiumin the culture solution, almost as effectively as by increasedpotassium supply. Extreme potassium deficiency yields chromatogramsclosely resembling those from more moderately deficient plants. When a low rubidium supply accompanies potassium shortage thedisturbances occasioned by potassium deficiency, both in growthand in amino-acid distribution, are diminished, but a higherrubidium supply leads to toxic symptoms in the plant; largeincreases in the contents of the two amides and of their parentacids are then found, this being the only condition encounteredthat leads to simultaneous accumulation of both these typesof substances.     

贮藏温度和气体组成对苹果乙烯生物合成的影响

苹果果实贮藏在高变温条件下(10℃开始,以后降至0℃)的空气中,随着乙烯形成酶(EFE)和ACC合成酶活性的增高,果实内乙烯浓度迅速上升,ACC和MACC积累。低温(0℃)抑制乙烯生成,ACC和MACC也有积累,但保持较高的EFE,促进ACC合成酶不断上升。低温气调(CA)(3％CO_2,3％O_2)显著抑制乙烯生成和相应的酶活性。高变温情况下,先提高CO_2浓度至12％,然后,随温度变化CO_2降至6％,形成双变气调。双变气调对乙烯生物合成的抑制作用与CA相同。     

The Effect of Calcium Nutrition of Ethylene-induced Abscission

The influence of calcium nutrition on ethylene-induced abscission was studied by growing cotton (Gossypium hirsutum L. cv. Stoneville 213) and bean (Phaseolus vulgaris L. cv. Resistant Black Valentine) plants for several weeks in nutrient solutions containing 2, 10 (normal level), 15, or 20 meq/l of calcium, and then treating the plants with ethylene. Increasing the calcium level of cotton from 2 to 20 meq/l resulted in a 9-fold increase in the calcium content of the abscission zone and a maximum reduction of 25% in the amount of leaf abscission induced by ethylene (9 μl/l). Bean plants grown on 10, 15, or 20 meq/l calcium solutions showed corresponding increases in the calcium content of the abscission zone but showed no significant differences in the rate of ethyleneinduced abscission. Only at the lowest calcium level of 2 meq/l, where deficiency symptoms became apparent, was a significant effect observed. These results suggest that under normal cultural practices calcium nutrition has little influence on the rate of ethylene-induced abscission.     

A Compartment Model of the Effect of Early-season Temperatures on Potential Size and Growth of 'Delicious' Apple Fruits

A compartmental growth model was developed to describe expansionof ‘Delicious’ apple fruit diameter and the effectof early-season temperatures on potential size at harvest. Themodel was based on the assumption that growth may be describedas a function of transfer between two conceptual compartments.Under this scheme, the first compartment represented all tissuecontributing to the setting of potential fruit size (determinedas the integral of its output) whereas the second compartmentrepresented all other fruit tissue whose growth actualized thatpotential. Expansion of both compartments was assumed to havea temperature response with an optimum, whereas an aging processwith an asymptotic temperature response controlled transferto the second compartment. Model parameters were estimated byfitting to data from controlled environment experiments in whichearly-season temperature conditions were varied. Predicted fruitgrowth curves showed close agreement with measured diameterdata. The results were consistent with a two-fold impact ofearly-season temperatures on apple fruit size: an immediate,direct effect on growth rate and an enduring effect, mediatedthrough fruit cell number or resource allocation to young fruit,reflecting the establishment of a potential that subsequentgrowth actualizes.Copyright 1999 Annals of Botany Company. Malus domesticaBorkh., apples, ‘Delicious’, fruit growth, models, temperature, potential size, cell division.