Secondary Tillers Research Articles

Effects of Foliar and Root-Applied Benzylaminopurine on Tillering of Rice Plants Grown in Hydroponics

Many studies have confirmed that exogenous cytokinins increase tillering in grasses as wheat, oat and barley. In this study, the effects of benzylaminopurine (BA) on tillering of two rice cultivars, North Rose with low tillering ability and Sasanishiki with high tillering ability, were examined using hydroponics. Foliar spray of BA was applied to both cultivarsat the 6-leaf stage. Root application of BA was used to Sasanishiki at the 8-leaf stage. Both root-applied and foliar-sprayed BA retarded the increase of tillers and resulted in significant decrease in tiller numbers per plant. The result indicated that primary tillers were much more affected than secondary tillers. Leaf production on the main stem was also temporarily inhibited with the exception of foliar spray to plants of cv. Sasanishiki. The effective concentration of BA on tillering was over 0.01μM for root application and 100 μM for foliar spray. Magnitude of effect of root application was greater than that of foliar spray in cv. Sasanishiki. Foliar-sprayed BA mainly inhibited tillers that are at the stage of differentiation of tiller buds from appearance. Root-applied BA could further inhibit the growth of tiller buds into tillers. In conclusion, BA inhibited the tillering of rice plants rather than promoting it, whichis inconsistent with general description of cytokinin roles.

Freezing of barley studied by infrared video thermography.

Freezing of barley (Hordeum vulgare), Hordeum murinum, and Holcus lanatus was studied using infrared video thermography. In the field, ice could enter H. lanatus leaves through hydathodes. In laboratory tests with barley, initially 0.4% of the leaf water froze, spreading in alternate strips of high and low freezing intensity longitudinally at 1 to 4 cm s(-1), and simultaneously spreading laterally at 0.3 cm s(-1). Similar results were obtained in the field with H. lanatus. A distinct second, more intense, freezing event spread slowly from the margins of the leaves toward the midrib. Organs of uprooted barley tested in the laboratory froze in this order: nucleated leaf, roots, older leaves, younger leaves, and secondary tillers. When ice spread from one leaf to the rest of the plant the crown delayed spread to the roots and other leaves. There was a longer delay above than below -2 degrees C, helping to protect the crown from freezing during mild frosts. Initial spread of freezing was not damaging. However, the initial spread is a prerequisite for the second freezing event, which can cause damage. The route of the initial spread of ice may be extracellular, drawing water from more gel-like parts of the cell wall.

Which Roots Penetrate the Deepest in Rice and Maize Root Systems?

Deep penetration of an axile root is one of the important factors that allow crops to form deep root systems. In this study, the nodes from which the deepest penetrated roots had emerged were examined at the heading stage in upland rice and maize grown in large root boxes and in the field. Both experiments were designed to measure the direction, length, and rooting nodes of each root. In maize, the growth angles of axile roots increased with vertical elongation as rooting nodes acropetally advanced. The roots that emerged from the lower nodes, namely from coleoptilar to the second node, exhibited conspicuously horizontal elongation in the field, reaching 2.3 m in width at the maximum. The roots that emerged from higher than the fifth node were too short to penetrate deeply. Thus, these roots became the deepest root in less or no probability under field conditions. On the other hand, the fourth nodal root, which had an intermediate growth angle and length, had the highest probability. In upland rice, the deepest roots emerged from the nodes lower than the forth node on the main stem in the root boxes. In the field, however, the deepest roots emerged at later stages, that is, the roots from the middle nodes on the main stem and from the low nodes on the primary and secondary tillers were the deepest roots. Five out of nine of the deepest roots were from the prophyll nodes in three field-grown upland rice. The deepest roots from the same plant were estimated to have emerged and grown at approximately the same stage.

Free‐Air CO2 Enrichment Effects on Apex Dimensional Growth of Spring Wheat

Although primordium initiation in wheat (Triticum aestivum L.) has been extensively researched, a complete description of the growth dynamics of the apex at elevated CO2 concentrations is lacking. This study determined the rates of main stem and tiller apical elongation and widening in plants grown under two levels of CO2 concentration. Spring wheat was grown at the University of Arizona's Maricopa Agricultural Center at elevated (550 μmol mol−1) or ambient (370 μmol mol−1) CO2 concentrations. Individual plant samples were collected at different developmental stages and dissected. After dissection, the lengths and widths of the apices of the main stem (MS), coleoptile tiller (TO), primary tillers (T1, T2, and T3), and secondary tillers (T00, T01, T02, T10, Tll, and T12) were measured with a stage micrometer. Apex dimensions were fitted to an exponential model. Elevated CO2 increased the apex lengths of T2 at the double ridge stage, and of T3 and T10 at the double ridge and the terminal spikelet stages, and the apex widths of T2 at double ridge stage, and of T2, T3, T10, and Tll at the flag leaf appearance stage. Combining these results with a parallel study, the longer apices did not have more spikelet primordia, but wider apices had more floret primordia. Elevated CO2 changed apex elongation or widening patterns within a plant by enhancing elongation or widening rates of the MS, and laterformed tillers. Earlier‐formed tillers were less responsive to elevated CO2 levels. This information will be used in modeling wheat apical development and grain production in the elevated atmospheric CO2 environments of the future.

Varietal Difference in the Relationship between the Number of Panicles per Hill and the Number of Spikelets per Panicle on the Main Stems and on Primary and Secondary Tillers of Rice.

Varietal differences in the number of panicles per hill and in the relationship between the number of spikelets per hill and the number of spikelets per panicle on each order tiller in the rice plant were investigated. The number of panicles per hill among the rice varieties studied ranged from 18 to 30. Although this difference was due to the number of panicles on the primary and secondary tillers, it was more greatly influenced by the latter. No significant relationship was observed statistically between the number of panicles per hill and the total number of spikelets per hill. However, the number of panicles per hill showed a significant negative correlation with the number of spikelets per panicle on each tiller and also with the average number of spikelets per panicle on the hill. The slope of the regression line for the relationship of the number of spikelets per panicle on each order tiller to the number of panicles per hill was in the following order : main stem < primary tiller < secondary tiller. The varieties with a larger number of panicles per hill showed smaller differences in the number of spikelets per panicle among each tiller. The number of spikelets on the main stems showed a significant positive correlation with the number of spikelets per panicle on the primary and secondary tillers. Thus the varieties that had larger numbers of spikelets on the main stems also had large numbers of spikelets per panicle on the primary and secondary tillers.

Vulpia ciliata Dumort. ssp. ambigua (Le Gall) Stace &amp; Auquier (Vulpia ambigua (Le Gall) More, Festuca ambigua Le Gall)

<i>Vulpia ciliata</i> Dumort. ssp. <i>ambigua</i> (Le Gall) Stace &amp; Auquier (<i>Vulpia ambigua</i> (Le Gall) More, <i>Festuca ambigua</i> Le Gall)

Free‐Air CO2 Enrichment Effects on Rate and Duration of Apical Development of Spring Wheat

Rates and durations of individual phases of wheat (Triticum aestivum L.) apical development are among the most important factors that determine yield components. Because atmospheric CO2 has been increasing steadily, it is important to evaluate the effects of elevated CO2 on wheat development. This study was conducted to determine rates and durations of leaf, spikelet, and floret primordium initiation in a Free‐Air Carbon Dioxide Enrichment (FACE) system. Spring wheat (cv. Yecora Roja) was planted at the University of Arizona Maricopa Agricultural Center. The two CO2 concentrations were 550 (elevated) and 370 (ambient) μmol mol−1 CO2. Individual plant samples were collected every 3 to 4 d. We dissected the main stem (MS), coleoptile tiller (T0), primary tillers (T1, T2, and T3) and secondary tillers (T00, T01, T02, T10, Tll, and T12) and counted primordia. Apex primordium data were fitted to a four‐piece linear‐spline segmented regression model with the SAS proc NLIN. No influence of elevated CO2 (550 μmol−1 on leaf primordium initiation of MS was detected. Nevertheless, CO2 enrichment significantly increased rates of spikelet primordium initiation of MS, T1, T2, T10, and Tll, and diminished the durations of spikelet development phase of MS, TI, T2, T3, T10, and T11. Within the floret phase, CO2 enrichment significantly increased rates of floret primordium initiation of MS, TO, T1, T2, and T3, and diminished the time to the completion of floret primordium initiation of MS, T0, T1, T3, and T11. The information from this study will be utilized to predict wheat apical development and grain production in the elevated atmospheric CO2 environments of the future.

Physiological Aspects Related to Tolerance of Spring Wheat Cultivars to Septoria tritici Blotch

ABSTRACT The susceptible wheat cultivar Miriam exhibited tolerance under severe infection of Septoria tritici blotch (STB). Nethouse and greenhouse trials confirmed former field results in which losses in grain weight of 'Miriam' wheat due to STB infection were significantly lower than those of the susceptible cultivar Barkai, under equivalent severity and the same disease progress curve. Several physiological mechanisms that may explain this tolerance of 'Miriam' wheat were studied. A comparison between protected and infected plants proved that carbohydrate reserves in the culms and other vegetative plant parts did not account for the lower losses in grain weight of 'Miriam'. Each tiller was shown to be independent in its supply of carbohydrates to its grains, and no import from secondary tillers was observed. Differences in the ratio between grain weight and vegetative biomass could not explain the sustained grain filling of infected plants of 'Miriam'. The daily balance of CO(2) exchange of the ears was negative, since carbon fixation by the spike in the light was more than counterbalanced by night time spike respiration. Radioisotope studies revealed that mature, infected 'Miriam' plants maintained as large a percentage of the carbohydrates fixed at the vegetative stage and early grain filling as healthy plants. On the other hand, under the same conditions, infected 'Barkai' plants lost a larger fraction of these carbohydrates. The rate of carbon fixation per unit of chlorophyll and per residual green leaf area of infected 'Miriam' was higher than in healthy plants. It is proposed that this enhancement of photosynthesis in residual green tissue of infected plants of the tolerant cultivar Miriam compensates for the loss of photosynthesizing tissue due to STB.

Effects of Combined Practice of Nitrogen Application Regime with Sparse Planting on the Growth and Yield of Rice.

Rice cultivars Akitakomachi and Hitomebore were cultivated in the field using an on-farm developed system ; no basal dressing of nitrogen combined with sparse planting (Exp plots). Their growth and yield were analyzed as compared with rice cultivated by general practice (Cont plot) with respect to the improvement of yield. In the Exp plots, nitrogen application was omitted at basal dressing but carried out as top dressing from 8th leaf age onward. Compared with the Cont plot, leaf expansion and tillering in the Exp plots were slower, the maximum leaf area index being about 4, whereas it was about 6 in the Cont plot. In the Exp plots, the percentage of fruitful culms was relatively large, but the panicle number m-2 was small, which resulted in a small spikelet number, less than 30, 000. The percentage of ripened grains was significantly larger, but the yield was 5-10% lower than that of the Cont plot. The panicle number per hill of primary tillers was not largely different among the plots, but that of secondary tillers was relatively large in the Exp plots. The fruitful culms of both primary and secondary tillers appeared to develop from upper node orders in the Exp plots as compared to the Cont plot. The panicles of secondary tillers in the Exp plots were larger than those in the Cont plot with respect to panicle weight, panicle length and leaf weight per panicle. Relative light intensity in the canopy was significantly larger at both booting and middle ripening stages in the Exp plots as compared to that in the Cont plot.

Panicle emergence of tiller types and grain yield of tiller order for direct-seeded rice cultivars

Grain yield of rice ( Oryza sativa, L.) tillers is critical to rice crop yield and quality but relatively little is known about variations that occur among panicles and grains for tiller types and emergence orders of direct-seeded rice cultivars. The objective of research was to examine how tillering may affect yield and quality at low plant population densities with profuse tillering. Single rice plants were grown in pots in a greenhouse in 1990 and in 1992 and in the field in 1991. The aim was to maximize tillering and thus better see effects of tiller emergence order and type on yield and panicle emergence. Culm and panicle emergence dates were successively later for primary, secondary, and tertiary tillers but with a smaller delay among panicle emergence dates than was observed for tiller emergence. Grain yield of tillers was related more to emergence order than to tiller type. Secondary and tertiary tillers in sufficient numbers could cause delays in crop grain maturity. Specifically, the beginning of grain-filling (closely following top anthesis) was 1 to 5 d later for primary tillers and 3 to 9 d later for secondary tillers, compared to main stems. These data indicate direct-seeded rice cultivars have partial but not complete synchrony of panicle emergence. Consequently, production strategies that increase preflood N to increase tillering in thin (sparsely populated) rice stands, could potentially delay maturity of the crop as well as increase yields.

Variation in Tillering and Geographical Distribution of Foxtail Millet(Setaria italica P. Beauv.).

Detailed analysis of tillering in foxtail millet (Setaria italica P. Beauv.) was carried out. The tiller development in 16 strains was observed throughout the growing season. Strains were classified into four tillering types, Type I, Type II, Type 111 and Type IV. Type I strains had the largest number of tillers with many primary tillers on the main culm, and further secondary and tertiary tillers. This tillering pattern is very similar to that of green foxtail (S. viridis P. Beauv.), the probable ancestor of foxtail millet. Strains of Type 11 produced only one or two primary tillers and no secondary tillers. Type 111 strains were non-tiller-ing and produced only one panicle on the main culm. It is supposed that Type I, which having high tillering capacity, was the first type domesticated from green foxtail. Types II and 111 subsequently differentiated from Type I by obtain-ing strong apical dominance.

Hypersensitive reaction and induced resistance in rice against the Asian rice gall midge Orseolia oryzae

AbstractRice seedlings of the resistant variety Phalguna showed premature tillering, browning of central leaf, and tissue necrosis at the apical meristem following artificial infestation with avirulent biotype 1 of the Asian rice gall midge, Orseolia oryzae (Wood‐Mason) (Diptera: Cecidomyiidae). Tissue necrosis representing a typical hypersensitive reaction (HR), accompanied by maggot mortality, was observed within 4 days after infestation. However, reinfestation of secondary tillers subsequent to HR in primary tiller, did not lead to HR in secondary tillers though maggot mortality was seen. Artificial infestation with the weed gall midge O. fluvialis did not result in HR either in gall midge susceptible TN 1 or resistant Phalguna rice varieties. Resistance in Phalguna against the virulent biotype 4 could be induced by either prior, simultaneous, or subsequent infestation with the avirulent biotype 1. The duration of effectiveness of such induced resistance varied with the sequence and time lag between infestations.

Studies on Lateral Buds Growth into Ratoon Tillers in Early-season Culture of Rice Plants.

The yielding ability and the effect of fertilization on yield were investigated in ratoon crop rice in early-season cultures. The total leaf number of each tiller in the ratoon crop was compared with Katayama's theoretical total number of leaves. The ratoon crop produced about 30% of the grain yield of the parent crop. Fertilization of the ratoon crop increased the panicle number per hill, resulting in an increased yield. Ratoon tillers were separated from the main stem to determine their tillering position on the stem, and to find the effect of fertilization on regrowth of tillers. Yield increase by fertilization was mainly due to the increase in the number of ripened secondary tillers. Tillers had 2∼3 more leaves than the total leaves expected from the theory of synchronous growth of leaves and tillers. The investigation of growth of lateral buds at each growth stage of the parent crop showed that the relation between growth of the main stem and lateral bud growth of ratoon tillers was not synchronized, resulting in the increase of total leaf number over the theoretical one.

Causes Of Multimodal Moisture Content Frequency Distributions Among Rice Kernels

In a greenhouse study, individual kernel moisture content was measured for the main stem, and for primary, secondary, and tertiary tillers in five plants (replicates) per harvest day for nine harvest days. One of the objectives was to determine whether the multimodal distribution of number of kernels versus moisture content observed in the field (Kocher et al., 1990; Siebenmorgen et al., 1992) could be attributed to the location where the seed was borne with respect to main stem or tillers. Results and analysis of the data revealed that the main stem and primary and secondary tillers exhibited very similar, multimodal distribution patterns. Therefore, the different moisture content peaks or modes could not be explained by main stem or tiller influence. However, a possible explanation of the multimodal frequency distribution pattern, based upon the change in moisture content of an individual rice kernel during its development, is presented.

Tiller Development in Salt‐Stressed Wheat

Wheat (Triticutna estivum L. emend Thell.) grain yields are highly dependent upon the number of spike‐bearing tillers produced per plant. Salinity, drought, and other environmental stresses can greatly affect the developmeanntd v iability of tillers. Wed eterminetdh e effects of soil salinity on the occurrence and rate of tiller development and the incidence of tiller abortion in spring wheat cultivars, Anza and Yecora Rojo. Plants were grown in Pachappa fine sandy loam soil (mixed thermic, Mollic Haploxeralf)in outdoor lysimeters. Three salinity treatments were imposed by irrigating with waters containing equal weights of NaCl and CaCl2 (electrical conductivities of ≈ 1, 12, or 18 dS m−1). Salinity significantly decreased the number of primary and secondary tillers in both cultivars. Soil waters salinities ≥7.5 dS m−1 (mean electrical conductivity of the soil water in the rootzone during tiller development SW) eliminated most of the secondary tillers and greatly reduced the number of TO, T3, and T4 tillers. However, the percentage of tillers producing spikes actually increased at SW up to 8 dS m−1. Higher salinities reduced the percentage of tillers with spikes, but not as much as the reduction in tillers. Tiller and spike production per plant decreasead bout 0.13 to 0.15 organs for each unit increase in SW. Of all the potential tillers these cultivars can produce, the primary tillers on Leaves 1 and 2 (i.e., T1 and T 2) were the least susceptible to salt stress, partly because they emerged before salinity builds up during the irrigation season. Adjusting planting densities to increase the number of anticipated spike‐bearing culms per unit area could help to maintain yields on salt‐affected soils.

Irrigation and Culm Contribution to Yield and Yield Components of Winter Wheat

AbstractWater is generally the limiting factor in U.S. Great Plains wheat (Triticum aestivum L.) production. With increasing demands for limited water, improving the efficacy of irrigation is critical. One technique is to irrigate during responsive stages of crop development, but few studies have examined this approach. This 2‐yr study on a Nunn clay loam soil (fine, montmorillonitic, mesic Aridic Argiustoll) was designed to examine the effects of irrigation, based on stage of crop development, on winter wheat yield, yield components (on a plant basis), and specific culm responses. In the first year, the treatments were control (dryland), and irrigation at late jointing. In the second year, the treatments were dryland, irrigation at late jointing, irrigation at anthesis, and irrigation at both late jointing and anthesis. Irrigation at late jointing or anthesis significantly increased grain yield and the most important yield component (spikes per plant), as well as spikelets per plant, number of kernels per plant, and kernel weight per plant. The increased spikes per plant in the irrigation treatments, particularly with late‐jointing irrigation, was due to reduced tiller abortion. Increased yield was primarily due to the contribution of more secondary tillers (T10, T11, T20, T21, T30, and T31) that produced spikes. The contribution of main stems to the total yield decreased from 92% to at most 86% with irrigation, although the dry weight of main‐stem spikes increased with irrigation. The contribution to total yield of the main yield‐producing tillers, Tl and T2, decreased from 20 to 15% and 19 to 15%, respectively, with irrigation. As with main‐stem spikes, irrigation also increased T1 and T2 spike dry weight. Therefore, the production of secondary spikes due to irrigation treatments was not at the expense of main stem or primary tiller spikes. If only one irrigation can be applied, irrigation at late jointing is recommended for central Great Plains conditions, due to its greater effect on tiller survival. This implies that developmental and physiological processes at late jointing are critical in determining final grain yield, and water stress should be avoided at this growth stage.

Studies on Heading Characteristics of Primary and Secondary Tillers in Rice(Oryza sativa L.). I. Influence of leaf cutting on heading characteristics of primary and secondary tillers.

同じ個体の主稈と分げつおよび分げつ相互間に幼穂発育及び出穂日の差が生ずるメカニズムを明らかにしようと試みた. イネ3品種, 農林1号, 日本晴, 農林8号を供試し, 水田土壌を詰めたa/2000ワグネルポットに直播土耕法によって野外で栽培を行った. 葉齢指数約70- 90の時期に伸長した葉を展開完了時に剪除し, 止葉の葉鞘から穂の先端が5 mm以上抽出したものを出穂と認め, その日付を止葉に記入した. 成熟期に抜き取り, 分げつ節位別に出穂日を記録整理した. 分げつの葉を展開完了時に剪除するとその分げつの出穂が遅れたが, それぞれの止葉葉位はほとんど変わらなかった. 出穂に対する分げつ葉剪除の影響はその分げつに著しく見られ, 葉を剪除しない分げつへの影響は少なかった. 剪葉による分げつの出穂遅延は早生品種で著しかった. 二次分げつと一次分げつの出穂日の関係は一次分げつと主稈の関係に類似しているが, 二次分げつ相互間の出穂日の異なることが分かった. 主稈とその二次分げつの出穂日の差は, 晩生品種より早生品種の方が大きかった. 剪葉処理により一, 二次分げつともに出穂が遅れたが, 二次分げつは一次分げつよりも更に遅れ, この傾向は早生品種で著しかった. また, 二次分げつの場合も剪葉処理の影響は剪葉処理を受けなかった分げつでは少なかった. 二次分げつの止葉葉位は一次分げつより増加する傾向を示したが, 剪葉処理の影響は認められなかった. 葉齢指数90の時期の分げつ別の幼穂長が長いほどそれの出穂日が早く,剪一次, 二次分げつの出穂の早晩は幼穂分化の早晩に基づいたものであると推察された.

Seasonal development of roots under perennial and annual grass pastures

Studies in the field and in a rhizotron were conducted to examine the root growth of Phalaris aquatica L. (phalaris), Dactylis glomerata L. (cocksfoot) and Lolium rigidum Gaudin (annual ryegrass). Root and tiller development of the perennial grasses in autumn was also studied. In the field, annual ryegrass developed a more extensive surface rooting system than phalaris and cocksfoot by spring in a favourable season. Early root development of annual ryegrass was poor where the first rains of the season did not occur until winter. Growth rates of annual ryegrass roots at depth were similar to phalaris in mid spring in the rhizotron. Phalaris had a higher proportion of live roots than cocksfoot prior to the first autumn rain. Cocksfoot did not regenerate a substantial new root system until it developed secondary tillers, about a month after initial rains. Collectively, these studies indicated that the seasonal development and extent of the root systems of cocksfoot and phalaris were different.

Stoffbildung, CO2‐Gaswechsel, Kohlenhydrat‐ und Stickstoffgehalt von Winterweizen bei erhöhter CO2‐Konzentration und Trocken‐streß

Abstract Dry Matter Production, CO2 Exchange, Carbohydrate and Nitrogen Content of Winter Wheat at Elevated CO2 Concentration and Drought Stress Methods of mathematical modelling and simulation are being used to an increasing degree in estimating the effects of rising atmospheric CO2 concentration and changing climatic conditions on agricultural ecosystems. In this context, detailed knowledge is required about the possible effects on crop growth and physiological processes. To this aim, the influence of an elevated CO2 concentration and of drought stress on dry matter production, CO2 exchange, and on carbohydrate and nitrogen content was studied in two winter wheat varieties from shooting to milk ripeness. Elevated CO2 concentration leads to a compensation of drought stress and at optimal water supply to an increase of vegetative dry matter and of yield to the fourfold value. This effects were caused by enhanced growth of secondary tillers which were reduced in plants cultivated at atmospheric CO2 concentration. Analogous effects in the development of ear organs were influenced additionally by competitive interactions between the developing organs. The content and the mass of ethanol soluble carbohydrates in leaves and stems were increased after the CO2 treatment and exhausted more completely during the grain filling period after drought stress. Plants cultivated from shooting to milk ripeness at elevated CO2 concentration showed a reduced response of net photosynthesis rate to increasing CO2 concentration by comparison with untreated plants. The rate of dark respiration was increased in this plants.

Effect of Water Shortage on Main Shoot Development and Tillering of Common and Spelt Wheat

AbstractWater stress was imposed by cessation of watering (CW) on bread wheats and, in some experiments two spelt wheats, during 9–17 days, starting at the 4–5 leaves stage. Main shoot foliar stages (MSS) were delayed by CW and the effect remained thereafter.The presence of side tillers (intact or partly destroyed by heat or potassium iodide (KI) was not beneficial to main shoot foliar development after the end of CW. Emergence of tillers after the onset of CW was also delayed, but the effect was small if timing was expressed in MSS. Secondary tillers were the most sensitive to water shortage, their number, size and foliar stage were drastically reduced.The two cultivars of spelt wheats were not less sensitive to CW than the bread wheat tested.