Tall Cultivars Research Articles

Effect of interrow spacing and weeding frequency on the performance of selected rice cultivars on hydromorphic soils of West Africa

Field experiments were conducted on hydromorphic soils at the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria to determine the effects of crop-management practices on rice yield. The performances of three rice cultivars at different crop densities and weeding regimes were investigated. Weed weight decreased significantly as the interrow spacing was decreased from 45 cm to 15 cm. Tillering and the number of rice panicles also decreased with reduction in interrow spacing. When rice was kept weed free, there was no significant difference in yield between rice planted at 15, 30 and 45 cm interrow spacing. However, when the crop was weeded once only at 30 d.a.s., yield was significantly reduced at the widest spacing. Yield reduction caused by weed competition at the wide interrow spacing was more pronounced in the semi-dwarf cultivar than in the taller cultivars. All cultivars competed better with weeds when grown at 15 and 30 cm interrow spacing than at the wider spacing used by most peasant rice farmers in West Africa.

Competition for water and nutrients in mixed stands of spring wheat

Grain yields, moisture extraction pattern, water use efficiency and NPK uptake were studied with three spring wheat cultivars grown in pure and mixed stands under three irrigation levels. The three spring wheat cultivars produced similar grain yields. None of the mixed stands yielded more than pure stands. Soil moisture extraction pattern of the three cultivars and their binary mixed stands was similar from the top layers, however, more moisture was extracted from deeper layers by the tall cultivar C 306 and mixed stands having C 306 as a component cultivar. The water use efficiency of the dwarf cultivar HD 2160 was higher than the other two cultivars. Two mixed stands, namely, 3 : 1 and 1 : 1 Kalyansona: C 306 had a higher water use efficiency than their pure stands but all other mixed stands were intermediate. The grain yield and NP uptake of the dwarf cultivar HD 2160 were less when it was grown in mixed stands, while that of semi-dwarf cultivar Kalyansona and tall cultivar C 306 were more when grown with cultivar HD 2160 than when grown alone or together. The K uptake of all the three cultivars was adversely affected when they were grown in mixed stands. Two or three irrigations increased the moisture extraction from top layers but decreased the water use efficiency as compared to one irrigation. Grain yield and NPK uptake of the cultivars and their binary mixed stands were more with two or three irrigations than with one irrigation.

Host-pathogen interaction between spring wheat and Septoria nodorum with reference to resistance breeding

Host-pathogen interaction between spring wheat and Septoria nodorum Berk. with applications for wheat breeding were studied. Ultrastructure of interactions was studied using electron microscopic techniques. Following inoculation, conidia of S. nodorum germinate, form appressoria anda penetration peg which directly penetrates through the cell walls. It is suggested that most penetration attempts fail because of cellular defence reactions, formation of papillae and cell wall alterations. Inoculation with low spore concentration reduced grain yield of Hankkija’s Taava cultivar by 10 % and 1000-grain weight by 14 %. Inoculation with high spore concentration on large plots of Tähti cultivar reduced grain yield by 32 % and 1000-grain weight by 18 %. Inoculation with high spore concentration on normal breeding plots of Tähti cultivar reduced grain yield by 35 % and 1000-grain weight by 21 % and the grain yield of Kadett cultivar by 27 % and 1000-grain weight by 20 %. Inheritance studies on F2 progenies of spring wheat crosses involving susceptible and moderately or highly resistant parents suggest that heredity component of symptom expression is moderate level and breeding success depends mainly on efficient screening techniques. Resistance was associated with tallness in crosses, and cultivar trials suggest that resistance is positively associated with late maturation time. Field screening techniques based on small plots and artificial inoculation showed that the most resistant entries were wild Triticum species and late and tall cultivars. Seedling plant tests based on attached seedling leaves and detached leaves revealed easily the most resistant and most susceptible cultivars. The overall correlation between seedling tests and field tests was quite high. The results are discussed in relation to wheat breeding strategies for resistance to S. nodorum.

Melhoramento do trigo: XII. Comportamento de novas linhagens e cultivares no Estado de São Paulo

Foram comparadas entre si vinte e uma linhagens e quatro cultivares comerciais de trigo através de ensaios instalados em diferentes localidades paulistas, analisando-se os seguintes parâmetros: rendimento de grãos, altura de plantas, ciclo em dias da emergência ao florescimento e da emergência à maturação, porcentagem de plantas acamadas, comprimento da espiga, número de grãos por espiga e por espigueta, número de espiguetas por espiga, peso de cem grãos, resistência à ferrugem do-colmo e da-folha em condições de campo e de casa de vegetação. Em condições de laboratório, foram realizados estudos da tolerância ao alumínio, em soluções nutritivas. Nos ensaios conduzidos em Campinas, em condição de irrigação por aspersão, destacaram-se, quanto à produção de grãos, as linhagens IAC-60 e IAC-67, e, nos de Capão Bonito, IAC-66, IAC-60 e IAC-69 apresentaram maior produtividade. As linhagens IAC-64, IAC-68, IAC-71 e IAC-60 destacaram-se em Tietê, e as linhagens IAC-67, IAC-63 e IAC-64 evidenciaram alta produção de grãos em Maracaí. As linhagens IAC-52, IAC-53, IAC-54, IAC-55, IAC-56, IAC-57, IAC-58, IAC-60, IAC-64, IAC-65, IAC-67, IAC-71 e o 'Alondra-S-46' mostraram plantas de porte semi-anão, diferindo significativamente do 'BH-1146', de porte alto. Em relação à ferrugem-do-colmo (Puccinia graminis f. sp. fruir), as linhagens IAC-62 e IAC-65 e o cultivar Alondra-S-46 foram resistentes às sete raças testadas em estádio de plântula em casa de vegetação e também em condições de campo. Em casa de vegetação, a linhagem IAC-64 foi resistente a quatro raças de P. recondita, agente da ferrugem-da-folha, e IAC-52 e IAC-55, a três raças desse patógeno. Em condição de infecção natural no estádio de planta adulta, as linhagens IAC-51, IAC-56, IAC-61, IAC-62, IAC-63 e IAC-67 apresentaram menor grau de infecção dessa ferrugem, enquanto IAC-51, IAC-60, IAC-63, IAC-68 e IAC-70, bem como 'BH-1146' e 'IAC-18',foram tolerantes à presença de 10mg/litro de Al3+ na solução nutritiva.

Comparison of a new triazole retardant paclobutrazol (PP 333) with ancymidol, chlorphonium chloride, daminozide and piproctanyl bromide, on stem extension and inflorescence development in Chrysanthemum morifolium Ramat

Several experiments in glasshouses at different times of the year have demonstrated that a new growth retardant, paclobutrazol (PP 333), applied as a single compost drench or as a foliar spray, is very effective in controlling stem extension in the pot chrysanthemum ( Chrysanthemum morifolium) ‘Bright Golden Anne’, a tall cultivar. Moreover, the concentration required, 30–50 mg a.i. l −1, was much lower than with a drench of chlorphonium chloride (Phosfon/Phosfleur), or with a foliar spray of daminozide (Alar/B-Nine) or piproctanyl bromide (Alden/Stemtrol). In two trials, a comparison of paclobutrazol and ancymidol (A-Rest/Reducymol) drenches indicated that, on a weight basis, the two compounds induced approximately equal dwarfing, whereas foliar sprays of paclobutrazol were more active than those of ancymidol, particularly at the lower concentrations. As before, at least 50–100 times the concentration of daminozide was needed than of paclobutrazol or ancymidol in order to induce an equivalent response. However, the variability in lateral stem length within a pot of 12 flowering shoots was a little higher with foliar sprays of paclobutrazol than with daminozide, possibly indicating that the amount of paclobutrazol transported to its site(s) of action varied more between shoots. Paclobutrazol produced similar delays in flowering (which invariably accompany commercially adequate reductions in plant height) to ancymidol and daminozide, whereas the delays with chlorphonium chloride and piproctanyl bromide were 2–4 days greater. In an experiment with the dark pink ‘Regal Anne’, daminozide caused some loss of flower pigmentation, but paclobutrazol and the other compounds did not.

Nitrogen and phosphorus requirements of different wheat plant types under dryland and irrigated conditions1

Abstract The wheat (Triticum aestivum L.) plant type in major producing areas of the U.S. is changing rapidly from tall cultivars to high‐yielding semidwarf cultivars. Objectives of experiments were to determine if nitrogen and phosphorus nutritional requirements differ between traditional tall cultivars and modern semidwarf cultivars under dryland and irrigated conditions. ‘Larned’, a tall cultivar; ‘Newton’, a semidwarf cultivar; and ‘Plainsman V, a high‐protein semidwarf cultivar, were grown with all combinations of three nitrogen fertilizer levels (0, 84, and 168 kg N/ha) and two phosphorus fertilizer levels (0 and 90 kg P2O5/ha) at Colby, Kansas for two years. Three levels of irrigation—dryland, limited irrigation, and full irrigation—were applied. Grain yields were highest with 84 kg N/ha under dryland and with 168 kg N/ha under irrigation. Phosphorus increased grain yield under dryland conditions one year, but had no effect under irrigated conditions. Cultivar X nutrition interactions from differen...

Relationship among nitrogen and phosphorus contents of vegetative parts and agronomic traits of normal‐ and high‐protein wheats1

Abstract Nitrogen and phosphorus fertilizers were applied at different levels to three hard winter wheat cultivars ranging in grain protein potential to elucidate their interaction and relationship to yield components. Plant N content was higher in the high‐protein cultivar than in the normal‐protein cultivars at jointing two years and at anthesis one year. Plant P content was higher in the semidwarf cultivars than in the tall cultivar and was unrelated to protein potential. All cultivars contained similar plant N and P levels at maturity. Nitrogen fertilization increased plant N content and decreased plant P content at all stages, whereas P fertilization usually increased plant P content but did not affect plant N content. Grain protein was correlated positively with plant N content at all stages and with plant P content at maturity. Grain yield was correlated positively with plant N content at anthesis but correlated negatively with plant P content at maturity. We concluded that high plant N content at ...

Response of wheat cultivars to dates of sowing under dryland conditions

SUMMARYField experiments made for 4 years between 1976–7 and 1979–80 in a semi-arid environment of north-west India showed that the productivity of dryland unirrigated wheat can be increased considerably by adjusting the date of sowing to conducive atmospheric temperatures. Sowing in the middle of November when daily mean temperatures ranged between 19 and 21 °C produced yields ranging between 2·6and 3·5t/ha (averaged over the 4 years) compared with 1·4–3·3 t/ha obtained from the crop sown by mid-October when the daily mean temperature ranged between 24 and 26 °C. The tall cultivar C 306, a derivative of winter x spring wheat cross, could withstand sowing at higher temperatures (mid-October) more than the spring wheats. High temperatures prevailing during the seedling stage of spring wheats shortened their vegetative growth and initiated early differentiation. Night temperatures above 13 °C coupled with day temperatures of 33–35 °C in the last fortnight of October adversely affected the tillering of spring wheats sown on 15 October and produced smaller spikes with few fertile spikelets.

Effect of Rice Cultivar Height on Infestation by the Least Skipper, Ancyloxypha numitor (F.) (Lepidoptera: Hesperiidae)1

Populations of immature Ancyloxypha numitor (F.) were monitored in 1979 and 1981 on three dwarf (60 to 75 cm) and three tall (118 to 122 cm) cultivars of rice. Significant (P < 0.05) differences in the number of A. numitor larvae per 100 tillers (1979) and the number of eggs, larvae, and total immatures per 100 tillers (1981) were noted between dwarf and tall cultivars. Similarly, a significant (P < 0.05) negative correlation existed between eultivar height and x total larvae (r = −0.85,4, df), and a highly significant (P < 0.01) negative correlation existed between cultivar height and x total pupae (r = −0.92, 4 df). The hymenopterous parasites Agathis n. sp., Pediobus n. sp., and Elachertus n. sp. were recovered from infested A. numitor larvae. Overall, A. numitor parasitism varied from 3.7 to 48.0%. Agathis n. sp. was the dominant parasite, comprising from 72 to 100% of the total parasite population. The increased A. numitor immature populations and defoliation on the dwarf rice cultivars evaluated here suggest the need for identification and development of dwarf eultivars with A. numitor resistance.

Amount of Outcrossing on Different Male Steriles of Rice1

The amount of outcrossing on three short stature male steriles of rice (Oryza sativa L.) was studied when planted in alternate rows with pollinators constituted of a mixture of tall cultivars. The seed set observed on the ‘Calady’ and ‘Earlirose’ genetic male steriles was very poor, indicating that neither can be considered useful in hybrid seed production or population improvement. The ‘Bit‐Co’ cytoplasmic male sterile source showed average seed set of 5.4% in 1978 and 32.5 % in 1979. The higher seed set in 1979 apparently was due to better synchronization of flowering of male and female plants. Some selfing occurs in this source, amounting to 3.5% in 1979.

Sterol composition of dwarf and tall Pisum sativum seedlings in relation to gibberellic-acid-enhanced shoot growth

Gibberellic acid (GA 3) stimulated shoot elongation in both dwarf and tall cultivars of pea, but more so in the dwarf cultivar. The sterol composition of shoots of both cultivars was similar, with sitosterol being the most abundant compound, followed by stigmasterol and campesterol. Cholesterol could not be detected. Following GA 3 application, levels of free sterols in whole shoots increased whereas glycoside levels tended to fall. The magnitudes of the changes in both classes of sterol were similar in both cultivars. Analyses of stems and leaves separately revealed a greater growth response to GA 3 in the former but no effect of the hormone on the sterol composition of either organ. It is concluded that GA 3 enhancement of shoot growth in pea is not mediated through quantitative changes in cell sterols.

Sterol composition of dwarf and tall Pisum sativum seedlings in relation to gibberellic-acid-enhanced shoot growth

Gibberellic acid (GA 3 ) stimulated shoot elongation in both dwarf and tall cultivars of pea, but more so in the dwarf cultivar. The sterol composition of shoots of both cultivars was similar, with sitosterol being the most abundant compound, followed by stigmasterol and campesterol. Cholesterol could not be detected. Following GA 3 application, levels of free sterols in whole shoots increased whereas glycoside levels tended to fall. The magnitudes of the changes in both classes of sterol were similar in both cultivars. Analyses of stems and leaves separately revealed a greater growth response to GA 3 in the former but no effect of the hormone on the sterol composition of either organ. It is concluded that GA 3 enhancement of shoot growth in pea is not mediated through quantitative changes in cell sterols.

Influence of Growth Stage and Cultivar on Symptom Expression in Marigold, Tagetes sp., Infected by Pseudomonas syringae pv. tagetis1

Abstract The reaction of 39 marigold cultivars to Pseudomonas syringae pv. tagetis Young, Dye &amp; Wilkie was determined. Three new symptoms were observed in addition to large necrotic leaf spots with or without apical chlorosis: flecks and leaf spots both surrounded by chlorotic halos and apical chlorosis without leaf spots. Symptoms develop only on vegetatively growing tissue; new symptoms do not develop on mature tissue. Tall cultivars generally were more susceptible than dwarf cultivars.

Inheritance of Dwarfness in Three Oat Crosses and Relationship of Height to Panicle and Culm Length1

A stiff‐strawed, dwarf oat (Avena sativa L.) line (CI 8447) was crossed to its parental line (NC 2469), a medium‐height cultivar (‘Otee’), and a tall cultivar (PI 258595). All F1 plants were semidwarf for plant height, and all F2 distributions for height were skewed toward the dwarf‐parent mean. Variation for plant height was continuous in the F2 populations from all crosses, but F3 families were readily classified into discrete dwarf, tall, and segregating families. The ratios of parental to segregating families fitted those expected for a model with a difference for one gene. The continuous variation for plant height in the F2 and minor variation within parental type F3 families was attributed to minor effects of modifying genes plus environment. The symbol Dw‐7 was assigned to the single, partially dominant gene. This gene may be useful in developing semidwarf, lodging‐resistant cultivars.In all three crosses, panicle and culm length were correlated with total plant height and the relationship was linear.

Effects of acute gamma irradiation, developmental stages and cultivar differences on yield of gamma-2 plants in wheat and sorghum

Plants (gamma-1) from three cultivars each of wheat (Yecora, Pari and Chenab-70) and sorghum (Pq.7.dwarf, Ks.12.medium dwarf and Ts.100.tall) were irradiated (wheat: 0.5–7 kR; sorghum: 1–10 kR) at three developmental stages (1-leaf, ear emergence and anthesis). Seeds borne by gamma-1 plants (gamma-2 seeds) were collected from three developmental stages and raised as gamma-2 plants in the subsequent year. In general, germinability and grain yield of gamma-2 seeds decreased the later the gamma-1 plants were irradiated in the life cycle. The yield of gamma-2 plants was most reduced when gamma-1 plants were irradiated at the anthesis stage. Yield of gamma-2 plants was least affected when gamma-1 plants were irradiated at the 1-leaf stage of irradiation. Significant increases in yields were observed at certain exposures in wheat (0.5 kR) and sorghum (2–3 kR in dwarf and medium dwarf cultivars, and at 1–3 kR in the tall cultivar).

RuBP carboxylase activity in wheat following ear emergence and evaluation of the role of ear

Ribulose bisphosphate carboxylase activity and chlorophyll content were measured in the leaves and reproductive parts of two wheat cultivars after ear emergence. The chlorophyll content of the flag leaf was mostly higher than that of the awns and glumes. Awns had the highest chlorophyll content among reproductive parts. Light transmission to the lower leaves was higher in the dwarf cultivar Moti than in the medium tall cultivar Kalyansona. RuBP carboxylase activity in Kalyansona leaves was higher than in Moti leaves. In postanthesis stages there was no difference in RuBP carboxylase activity in the flag leaf and lower leaves between cultivars. Awns had the maximum activity of RuBP carboxylase followed by glumes and grains among ear parts. The relative capacity for photosynthesis in the ear parts was several times higher than in the flag leaf on a unit chlorophyll basis. It is suggested that in a crop canopy in the field, the spike(ear) may have a greater importance in grain development than has been previously estimated.

Weed Control in Cassava Cultivation in the Subhumid Tropics

Abstract Field trials were carried out over a three year period in an alfisol in a subhumid tropical environment to evaluate the effectiveness of hand-weeding frequencies and several herbicides for weed control in cassava (Manihot esculenta Crantz). Uncontrolled weed growth caused 40% reduction in root yield of short, profusely branching cassava cultivar while a 68% reduction in root yield was observed in separate studies involving a tall non-branching cultivar. Two or three properly timed hoe weedings gave crop yields that were as good as keeping the plots weed free throughout the growing season. Although pre-emergence application of fluometuron at 2.0 to 3.0 kg a.i./ha or diuron at 2.0 kg a.i./ha used singly gave good weed control and crop yield, the efficacy of these herbicides was greatly improved by tank mixing each of them with alachlor or metolachlor at 3.0 and 2.0 kg a.i./ha respectively. Excellent crop yield was also observed where atrazine and metolachlor was applied pre-emergence at 2.5 kg a.i....

Productivity of single-culm and multi-culm plants of winter wheat cultivars in field conditions

The productivity of 1-, 2-, and 3-culm plants of three winter wheat cultivars was studied under field conditions in three spatial arrangements. The treatments with 2- and 3-culm plants produced higher grain yield per unit area than the treatments with 1-culm plants. This was explained as the result of a higher interplant than intraplant competition. It seems that the interplant competition is lower with dwarf than with tall cultivars. The secondary culms may be as productive as the primary ones if there are only a few of them per plant and if they develop before the beginning of winter. If the tillering takes place mainly in spring, the differences in productivity between the primary and secondary culms are considerable. Under conditions of dry autumns and late planting not the tillering must be taken as the main factor which regulates the optimal number of spikes/m2, but the high planting rate.

Breeding Methodology in Wheat. II. Productivity, Harvest Index, and Height Measured on F2 Spaced Plants for Yield Selection in Spring Wheat1

Three crosses of spring wheat (Triticum aestivum L.) involving the cultivar ‘Glenlea’ as a common female parent were used to evaluate the use of productivity, harvest index, and height in a combined index selection procedure on F2 spaced‐plants as selection criteria to identify high‐yielding F4 bulks. A space‐planted and solid‐seeded trial of seven tall cultivars and seven semi‐dwarf cultivars (both groups including the parents involved in the crosses investigated), indicated that potentially high‐yielding tall cultivars could be selected from space‐planted populations using productivity. Semi‐dwarf cultivars (short cultivars), in contrast, could be selected from space‐planted populations using harvest index. Therefore, productivity was used as the selection criterion on tall F2 plants and harvest index was used as the selection criterion on short F2 plants for high yield potential. The results indicated that a combined index selection procedure utilizing productivity, harvest index, and height may be useful in increasing yield in spring wheat.

Chemical control of shoot growth and axillary inflorescence development inChrysanthemum morifoliumRamat with 2,3-dihydro-5,6-diphenyl-1,4-oxathiin

SummaryA substituted oxathiin (code name UBI-P293) was wholly effective as a growth retardant on pot-grown Chrysanthemum morifolium ‘Bright Golden Anne’, a tall cultivar, in a single foliar spray at concentrations up to 2 000 mg a.i.l-1. The application must be made at a later stage of growth than is normally recommended for daminozide; the delays in flowering were similar to those recorded for daminozide, i.e., less than with chlorphonium chloride or piproctanyl bromide. Unlike daminozide, UBI-P293 did not appear to change flower colour in a dark pink cv, Regal Anne. At higher levels the compound induced further decreases in stem extension and also inhibited the development of 50% or more of the axillary inflorescences, though the need for manual disbudding was not entirely eliminated. In order to achieve both height control and a substantial disbudding effect in one operation the concentration of the foliar spray and the timing of its application were critical. Too high a concentration at an ‘early’ sta...