Interaction Between Root and Leaf Disease Development in Barley Cultivars after Inoculation with Different Isolates of Bipolaris sorokiniana

The relationship between root and leaf infection in 11 cultivars of barley ( Hordeum vulgare ) by different isolates of Bipolaris sorokiniana was investigated in young plants. Roots of 10-day-old seedlings, grown in filterpaper rolls, and the third leaf of 17-day-old seedlings were inoculated with the different isolates and a Disease Development Index (DDI) was calculated.
The rate of lesion development in leaves was higher than in roots, indicated by generally higher DDI after leaf inoculation than after root inoculation. Significant differences in resistance were found among the barley cultivars. Inoculation with different isolates of B. sorokiniana caused significant differences in DDI for both roots and leaves. In the leaves, but not in the roots, a significant cultivar–isolate interaction was found. No significant correlations, neither in isolate aggressiveness nor in cultivar reaction between root and leaf, were observed.     

Genotypic and nutrition-dependent variation in water use efficiency and photosynthetic activity of leaves in winter wheat (Triticum aestivum L.)

Effects of high and reduced NPK nutrition on the genetic variation of components of water use efficiency at the leaf and whole-plant levels were examined in pot-grown old and modern cultivars of winter wheat (Triticum aestivum L.). At the subsequent growth stages, the photosynthetic rate (A), transpiration rate (E), leaf area (LA) and gas exchange efficiency (A/E) were measured on fully developed 4th, 5th, penultimate and flag leaves. At the plant canopy level, the total amount of water transpired was recorded during the whole life cycle to determine the efficiency of water use in the vegetative (WUEveg) and grain (WUEgen) matter formation. Considerable genotypic differences were found for the characters studied. The limited NPK supply caused a decrease in LA, A and A/E, but contributed to an increase in WUEgen. Examined cultivars (C) did not interact with nutrition levels (N) for these characteristics. However, the position of leaves (L) and the C x L and N x L interactions significantly affected the variance in leaf photosynthetic characteristics. A and A/E were negatively correlated with LA, and the flag leaves were photosynthetically less active and less efficient per unit area than the lower leaves. The whole-plant components of WUE were found to be more genetically stable than the photosynthetic leaf characteristics. Some modern cultivars tended to form leaves of higher A and A/E than the older ones, and this corresponds with a more efficient use of water in grain formation (WUEgen) of the former. Stay-green duration of flag leaves and harvest index showed positive correlations with WUEgen. However, no close associations were noticed between WUE components and stress tolerance, and the modern cultivars were usually less tolerant to NPK shortage.     

The effect of early blight disease caused by Alternaria solani on shoot growth of young tomato plants

The effect of increasing spore concentration of Alternaria solani (Early blight disease) on the shoot growth of young tomato plants was analysed. Changes in growth were related to the severity of infection which increased with increasing inoculum. Leaf production was not affected but dry weights and especially leaf expansion were decreased. The effective leaf areas of the five inoculated leaves (L1-L5 numbered from the plant base) were drastically decreased by expanding necrotic lesions and, to a lesser extent, by premature leaf fall. Healthy leaves expanding soon after inoculation (L6, L7) were markedly affected by the disease on the lower leaves and had decreased specific leaf areas (ratio of leaf area to leaf dry weight) but later formed (from L8) leaves were less affected and had greater specific leaf areas than equivalent leaves on uninoculated plants.     

STEM INFECTION OF COTTON BY XANTHOMONAS MALVACEARUM (E. F. SM.) DOWSON

Varying the position of stem inoculation, the concentration of inoculum and the age of plant affected the reaction of cotton, Gossypium sp., to infection with Xanthomonas malvacearum (E. F. Sm.) Dowson.
The extent of stem discoloration, internal and external, and the probability of disease ocurring in leaves by bacteria moving within the plant increased ( a ) the nearer the point of stem inoculation was to the apex, and ( b ) the higher the concentration of inoculum. The leaf symptoms were not the angular spots typical of primary leaf infection. Instead, bacteria seemed to lodge in, discolour and blacken sections of leaf veins. Then tissue next to the affected veins became water-soaked and leaf sectors dependent upon these veins died and dried. These symptoms usually developed 14 to 55 days after inoculation in the expanding leaves.
The amounts of stem discoloration and the probabilities of leaf symptoms developing were less when hypocotyls of old plants were inoculated than when hypocotyls of young plants were inoculated. The probabilities of leaf symptoms developing were similar, however, when young tissues in young and old plants were inoculated.
American cotton, Gossypium hirsutum , was less affected by stem inoculation than Egyptian cotton, G. barbadense. Of the resistance factors against primary leaf infection only B_6m gave appreciable stem resistance.     

Senescence and net photosynthesis of the flag leaf and grain growth of wheat in response to fungicide

Green leaf area and net photosynthesis of the flag leaves of Avalon and Maris Huntsman winter wheat crops were studied in relation to grain growth following the application of the fungicide propiconazole at flag leaf emergence. Disease levels were low during grain-fill, and were not significantly affected by the fungicide. Propiconazole significantly maintained green leaf area and photosynthesis per unit area during the period of rapid flag leaf senescence, but it had no effect on stem weight, grain growth or yield.     

Effects of Bean Leaf Age on Pathogenicity by Botrytis fabae

Leaves from field bean plants grown out of doors were inoculated with conidia of B. fabae immediately after detaching from stems. The oldest leaves developed more lesions than youngest ones, although they were not chlorotic. On intact plants at high humidities, established lesions on young leaves increased in size at only half the rate of those on old. but still green leaves. Seven days after inoculation a higher proportion of lesions on old leaves bore conidia than those on young leaves, but leaf age had no significant effect on numbers of conidia per mm² of lesion area. Young leaflets from bean plants grown in a controlled environment or in the field challenged with β. cinerea accumulated more phytoalexins than did old ones.     

Antibodies raised against yeast HSP 104 cross-react with a heat-and abscisic acid-regulated polypeptide in rice

Antibodies raised against yeast heat shock protein (HSP) 104 recognized a heat-inducible polypeptide with a molecular mass of 110 kDa in shoot tissue of young rice seedlings. Root tissue of the same age showed no immuno-reaction with yeast HSP 104 antibodies. The 110 kDa polypeptide of rice was also shown to be abscisic acid-inducible in young seedlings. Though this polypeptide was seen to be constitutively present in the flag leaf of 90-day-old field-grown plant, it was not much affected by either heat shock or abscisic acid in this case.     

Effects of Leaf Age, Inoculum Dose and Freezing on Development of Chocolate Spot (Botrytis fabae) Lesions on Field Bean (Vicia faba) Leaves

Botrytis fabae spore suspensions containing c. 1, 10, 10², 10³, 10⁴, 10⁵, or 10⁶ spores/ml were used to inoculate 5, 17 or 30-day-old field bean leaves. The percentages of the leaf areas covered by, chocolate spot lesions and the percentages of the leaf areas bearing conidiophores were assessed 1, 6, 12, 14, and 19 days after inoculation. The percentage of the area covered by lesions and the percentage of the area bearing conidiophores (logit-transformed) increased linearly with increasing spore concentration (log₁₀-transformed). The proportions of leaf areas covered by lesions and bearing conidiophores were both greater on 17 and 30-day-old leaves than on 5-day-old leaves. The rate of lesion growth increased with both increasing inoculum dose and increasing leaf age. Generally there was no interaction between the effects of leaf age and the effects of inoculum dose on either lesion growth or sporulation. Two days after inoculation with suspensions of either 10⁴ or 10⁶ spores/ml, 7-day-old leaves grown at 15°C were transferred to –16°C or 2.5°C or kept at 15°C for 4 days. Two days later more spores had been produced on leaves which had been frozen (–16°C) than on, leaves kept at 2.5°C.     

Leaf photosynthetic rate and mesophyll cell anatomy changes during ontogenesis in backcrossed <Emphasis Type="Italic">indica</Emphasis> × <Emphasis Type="Italic">japonica</Emphasis> rice inbred lines

The high-yielding indica rice variety, ‘Takanari’, has the high rate of leaf photosynthesis compared with the commercial japonica varieties. Among backcrossed inbred lines from a cross between ‘Takanari’ and a japonica variety, ‘Koshihikari’, two lines, BTK-a and BTK-b, showed approximately 20% higher photosynthetic rate than that of ‘Takanari’ for a flag leaf at full heading. This is a highest recorded rate of rice leaf photosynthesis. Here, the timing and cause of the increased leaf photosynthesis in the BTK lines were investigated by examining the photosynthesis and related parameters, as well as mesophyll cell anatomy during ontogenesis. Their photosynthetic rate was greater than that of ‘Takanari’ in the 13th leaf, as well as the flag leaf, but there were no differences in the 7th and 10th leaves. There were no consistent differences in the stomatal conductance, or the leaf nitrogen and Rubisco contents in the 13th and flag leaves. The total surface area of mesophyll cells per leaf area (TA_mes) in the 13th and flag leaves increased significantly in the BTK lines due to the increased number and developed lobes of mesophyll cells compared with in ‘Takanari’. The mesophyll conductance (g _m) became greater in the BTK lines compared with ‘Takanari’ in the flag leaves but not in the 10th leaves. A close correlation was observed between TA_mes and g _m. We concluded that the increased mesophyll conductance through the development of mesophyll cells during the reproductive period is a probable cause of the greater photosynthetic rate in the BTK lines.     

不同遗传背景下杂交籼稻功能叶与产量构成因素的相关性

为明确水稻功能叶与产量构成因素间的相关性,以不同遗传背景下籼稻的10个不育系和16个恢复系为亲本,按照NCII设计配制两套双列杂交组合,对水稻12个功能叶性状与8个产量性状构成因素进行了相关分析,结果表明：3片功能叶叶长与叶面积、剑叶宽、倒2叶宽等性状之间均存在极显著正相关,功能叶夹角之间也存在极显著正相关,但不同遗传背景对夹角性状与9个形态性状之间的相关性则存在明显差异,在第1套组合中,其相关系数均为负值,且相关均不显著;而第2套组合则相反。8个产量构成因素中,单株穗数与平均穗长、着粒密度、穗实粒数以及穗着粒数之间存在极显著负相关,平均穗长与穗着粒数、结实率与单株产量呈显著或极显著正相关,遗传背景对产量组成上有较大影响,在第1套组合中单株产量主要由结实率、单株穗数以及穗实粒数等性状决定,而在第2套中则主要由穗实粒数和结实率等性状决定。在功能叶与产量构成因素的相关中,叶长、叶面积、剑叶宽、倒2叶宽与着粒密度、穗实粒数以及穗着粒教等3个性状之间存在显著或极显著正相关。12个水稻功能叶性状与8个产量构成因素之间的主成分分析表明,在不同的遗传背景下,产量构成因素均主要受叶面积和叶夹角影响,两种不同遗传背景中其累积贡献率分别为69．8％和84．0％。     

Probenazole-induced accumulation of salicylic acid confers resistance to Magnaporthe grisea in adult rice plants

Probenazole (PBZ) is the active ingredient of Oryzemate, an agrochemical which is used for the protection of rice plants from Magnaporthe grisea (blast fungus). While PBZ was reported to function upstream of salicylic acid (SA) in Arabidopsis, little is known about the mechanism of PBZ-induced resistance in rice. The role of SA in blast fungus resistance is also unclear. The recommended application period for Oryzemate is just before the Japanese rainy season, at which time rice plants in the field have reached the 8-leaf stage with adult traits. Thus, the involvement of SA in PBZ-induced resistance was studied in compatible and incompatible blast fungus-rice interactions at two developmentally different leaf morphology stages. Pre-treatment of inoculated fourth leaves of young wild-type rice plants at the 4-leaf stage with PBZ did not influence the development of whitish expanding lesions (ELs) in the susceptible interaction without the accumulation of SA and pathogenesis-related (PR) proteins. However, PBZ pre-treatment increased accumulation of SA and PR proteins in the eighth leaves of adult plants at the 8-leaf stage, resulting in the formation of hypersensitive reaction (HR) lesions (HRLs). Exogenous SA induced resistance in adult but not young plants. SA concentrations in blast fungus-inoculated young leaves were essentially the same in compatible and incompatible interactions, suggesting that PBZ-induced resistance in rice is age-dependently regulated via SA accumulation.     

Components of Resistance to Early Blight in Four Potato Cultivars: Effect of Leaf Position

Components of early blight resistance were quantified in leaves of different ages in four potato cultivars. The components of resistance: incubation period (IP), lesion number (LN), early blight severity, lesion expansion rate (LER), latent period (LP) and spore production by lesion area (SPLA), were evaluated separately in the lower, middle and upper leaves of four potato cultivars. Plants of cultivar Aracy (resistant), Delta (moderately resistant), Desirée (susceptible) and Bintje (susceptible) were inoculated with an Alternaria solani isolate at the beginning of the flowering stage. Disease severity varied in different plant parts. In all cultivars, regardless of resistance, the smallest values of LN, and severity were recorded on the upper leaves, suggesting that young tissues are less susceptible. In cultivar Aracy, the IP was long, with small values of LN and LER and consequently, low values of early blight severity in all leaf positions were recorded. Although IP was long in cultivar Aracy, no differences between the moderately resistant cultivar Delta and the susceptible cultivars Bintje and Desirée could be detected for this component. The IP was only influenced by leaf position in cultivar Aracy. Clear differences in resistance levels among cultivars could be detected regarding LN, severity and LER. However, neither LP nor SPLA were associated with resistance level of cultivars or with leaf position. Analyses according to plant part suggest that evaluations on leaves of the middle third part are most suitable for screening for early blight resistance in potato.     

Effect of assimilate utilization on photosynthetic rate in wheat

Summary Two weeks after anthesis, when the grain is filling rapidly, the rate of photosynthesis by flag leaves of wheat cv. Gabo was between 20 and 30 mg CO₂ dm^-2 leaf surface hour^-1 under the conditions used. About 45% of flag-leaf assimilates were translocated to the ear, and only about 12% to the roots and young shoots.On removing the ear, net photosynthesis by the flag leaves was reduced by about 50% within 3–15 hours, and there was a marked reduction in the outflow of ¹⁴C-labelled assimilates from the flag leaves.Subsequent darkening of all other leaves on plants without ears led to recovery of flag-leaf photosynthesis, as measured by gas analysis and ¹⁴CO₂ fixation, and to increased translocation of assimilates to the roots and young shoots. Minor changes in the rates of dark respiration accompanied these major, reversible changes in photosynthetic rate.After more than a week in continuous, high-intensity light, the rate of photosynthesis by flag leaves of intact plants had fallen considerably, but could be restored again by a period in darkness, or by inhibiting photosynthesis in the ears by spraying them with DCMU. The inhibition of ear photosynthesis increased translocation of labelled assimilates from the flag leaf to the ears, without affecting leaf sugar levels.The application of TIBA to the culm below the ear inhibited auxin movement throught the culm, but had no influence on flag-leaf photosynthesis.These results suggest that, at least in this system, photosynthesis by the flag leaf is regulated directly by the demand for assimilates from the flag leaf and not indirectly through action in the leaf of auxins produced by the sink organs.     

珍稀濒危植物珙桐超氧化物歧化酶活性

采用比色法测定了不同年龄和部位珙桐叶的超氧化物歧化酶(SOD)活性,以探讨不同年龄级珙桐的生理生态适应性。结果表明:不同年龄同一生长期珙桐叶的SOD活性不同,同年龄级同层珙桐叶的SOD活性随叶位增加大致呈先升后降的变化;同叶位不同层及同层不同叶位的珙桐叶的SOD活性不同。珙桐叶SOD活性对生长期敏感,其活性随叶片的生长、衰老呈先升后降变化。即珙桐叶SOD活性受生物和非生物因子共同影响,且不同年龄级、叶位、层次均存在差异。     

A new life table of leaves ofPhaseolus vulgris L. in relation to their position within the canopy and plant density

In order to demonstrate in detail the relationship between the longevity and productivity of leaves within a canopy, a new life table approach, the ‘bioeconomic life table’, was applied to the leaves of kidney bean plants (Phaseolus vulgaris L.) in relation to planting density and their position within the canopy. The net photosynthetic rate for upper leaves under full daylight tended to decline gradually due to leaf senescence from about 20 days after leaf emergence, and for the lower leaves the decrease was very rapid due to both shading and senescence about 10 days after emergence. Analysis of the survivorship curves and daily surplus production of leaves suggested that the lower and middle leaves, especially the latter, survived without surplus production of dry matter after they had reached mean longevity, and while the upper leaves at high density had a much shorter mean longevity, they had very large values of daily surplus production throughout the survival period. For the total foliage, the summed value of accumulated surplus production during the survival period was about five times as large as the summed value of the dry weight of the dead leaves, regardless of planting density. The daily rate of canopy leaf respiration was almost proportional to that of canopy gross photosynthesis for the various leaf area indices of the canopy, so that there was no optimum leaf area index that maximized canopy daily surplus production.     

The Glycine-Glomus-Rhizobium Symbiosis : VII. Photosynthetic Nutrient-Use Efficiency in Nodulated, Mycorrhizal Soybeans

Four consecutive trifoliate leaves of 56-day-old symbiotic or nonsymbiotic soybean plants were evaluated individually for CO₂ exchange rates (CER), leaf area and dry weight, and leaf N, P, and starch concentrations. Plants had been inoculated with the vesicular-arbuscular mycorrhizal (VAM) fungus Glomus mosseae and Rhizobium japonicum, with either of the endophytes alone, or with neither at time of planting. Plants lacking one or both endophytes received N and/or P fertilizers to produce plants of equal total leaf dry weight in all four treatments. Photosynthetic P-use efficiency (CER per unit leaf P) was higher in the leaves of VAM plants than in P-fertilized plants regardless of the N source (N₂ fixation or combined N). Photosynthetic N-use efficiency was also higher in VAM than in non-VAM plants, but it was affected by the N source, with higher CER in the nodulated plants. The greatest differences in CER, starch accumulation and leaf area were found between the nonsymbiotic plants and those with both endophytes. Statistical evaluations of leaf parameters for treatment or nutrient concentration (N and P) effects between the tri-partite and the nonsymbiotic treatments showed significant changes in concentration of P, but not N, with decreasing leaf age. Both endophytes apparently enhance CO₂ fixation at N and/or P concentrations lower than those of the nonsymbiotic plants. The effects of the endophytes on CO₂ fixation were additive.     

Responses of Penultimate and Flag Leaves of Wheat to Different Nitrogen Supply

Uniculm wheat (Triticum aestivum L.) was grown to maturity at four concentrations of nitrogen corresponding to 3 (N1), 6 (N2), 9 (N3) and 12 (N4) g m^–2. Penultimate and flag leaves were examined throughout the ontogeny. Sub-optimal concentrations of N resulted in sharp decline in both area and dry mass of the leaves. Decline in leaf area was due to fewer mesophyll cells. Net photosynthetic rate (P_N) increased up to full expansion, remained constant for about a week and then declined. P_N, nitrogen, ribulose-1,5-bis-phosphate carboxylase/oxygenase (RuBPCO) amount and activity, chlorophyll and soluble protein contents were similar at all the N concentrations. Both amount and activity of RuBPCO in the flag leaf were about two fold higher as compared to penultimate leaf, but P_N was similar. This indicates the presence of an excess amount of RuBPCO in the flag leaf.     

Effect of Nitrogen Fertilizer on Photosynthesis of Several Varieties of Winter Wheat

The rates of gross photosynthesis of the flag leaf and the nextleaf below (second leaf) in crops of winter wheat were estimatedfrom the ¹⁴C uptake of the leaves after exposure to short pulsesof ¹⁴CO₂. The photosynthetic rates of both leaves during thegrain-filling period decreased with increase in nitrogen fertilizerbecause the intensity of photosynthetically active radiationwas less at the surface of the leaves in the dense crops withadditional nitrogen. In addition, the rate of photosynthesisat saturating light intensity was slightly decreased by nitrogen.The effects of nitrogen, in decreasing the rate of photosynthesisper unit area of leaf and in increasing the leaf-area indexof the top two leaves, were such that the photosynthetic productivityper unit area of land of the flag leaf was increased by nitrogenbut the productivity of the second leaf was unaffected. Applying180 kg N ha^–1 increased the productivity of the top twoleaves by a factor of 2.3 but increased grain yield by only1.8. The photosynthetic productivity of the second leaf duringthe grain-filling period was about half that of the flag leaf. There was no difference in photosynthetic rate per unit areaof leaves of Cappelle-Desprez and Maris Huntsman which couldaccount for the larger yield of the latter cultivar. There wasa slight indication that the leaves of the semi-dwarf cultivarsMaris Fundin and Hobbit photosynthesized faster than those ofMaris Huntsman. Triticum aestivum L., winter wheat, photosynthesis, nitrogen fertilizer     

Epidermal conductance in different parts of durum wheat grown under Mediterranean conditions: the role of epicuticular waxes and stomata

Abstract. Epidermal (non-stomatally-controlled) conductance from the fourth leaf, first node leaf, flag leaf and ear of durum wheat (Triticum turgidum var durum L.) grown under Mediterranean field conditions has been measured, along with leaf stomatal frequency and the amount and distribution of epicuticular waxes. Measurements were carried out on varieties and land-races from the Middle East, North Africa, ‘Institut National de la Recherche Agricole’ (INRA) and ‘Centra Internacional de Mejora de Maiz y Trigo’ (CIMMYT). Significant differences were observed among genotypes in the epidermal conductances (g_e) of the four organs. For each of the four organs tested, genotypes from the Middle East and CIMMYT showed higher g_e. values than those from North Africa and INRA. Ears showed epidermal conductances that were more than four times higher than those of leaves when g_e. values were expressed per unit dry weight. The amount of epicuticular waxes was higher in the fourth leaves, intermediate in the first node and flag leaves and lower in the ears. For each organ, g_e differences among genotypes were unrelated with the amount of epicuticular waxes. Removal of epicuticular waxes by dipping the organs into chloroform significantly increased the epidermal conductance for the fourth and first node leaves and the ear. However, this did not occur for the flag leaf. For the fourth leaf, g_e of intact leaves and g_e of leaves in which epicuticular waxes were removed were unrelated (r = -0.265). The regression coefficient of this relation for the first node and flag leaves showed values of 0.666 and 0.650 (P > 0.05), respectively, and values were even higher in the ear (r > m 0.892, P > 0.01). Scanning electron microscope analysis showed that wax bloom decreased from the fourth leaf to the flag leaf, whereas the extent of amorphous wax increased. Wax bloom in leaves consisted mainly of deposits of thin wax plates. In the ears and the adaxial surface of flag leaves, fibrillar waxes predominated. In the first node and flag leaves, the wax deposits on the adaxial side cover the surface of the leaf more densely and uniformly than those on the abaxial side. There was no significant correlation between g_e and total stomatal density, or between g_e and either adaxial or abaxial stomatal density for any sample of the three different leaves. The contribution of epicuticular waxes plus total stomatal frequency only explained 42.4, 11.8, 28.3 and 16% of g_e (per unit leaf area) variations for the fourth leaf, first node leaf, flag leaf and the combined variation of the three leaves together, respectively. From these results, it is concluded that complex interrelationship between different morphophysiological characteristics probably control g_e differences among genotypes and that these interrelationships differ for each different plant part.