BREEDING NEW COTTON VARIETIES TO FIT THE DIVERSITY OF CROPPING CONDITIONS IN AFRICA: EFFECT OF PLANT ARCHITECTURE, EARLINESS AND EFFECTIVE FLOWERING TIME ON LATE-PLANTED COTTON PRODUCTIVITY

2008 ◽  
Vol 44 (2) ◽  
pp. 197-207 ◽  
Author(s):  
EMMANUEL SEKLOKA ◽  
JACQUES LANÇON ◽  
ERIC GOZE ◽  
BERNARD HAU ◽  
SYLVIE LEWICKI-DHAINAUT ◽  
...  

SUMMARYIn most cotton-growing regions of West and Central Africa where rainfed conditions prevail, cropping conditions are highly diversified since the crop is planted over an extended period. We studied production and development patterns in 10 cotton (Gossypium hirsutum) varieties to determine the most efficient strategies that could be transformed into breeding traits. Four trials were carried out between 2002 and 2003 in two cotton-growing areas in Benin to compare the 10 varieties at three stand densities and two planting dates. The parameters monitored were the mean first flower opening date (FF), effective flowering time (EFT), plant height at harvest (HH), height to node ratio (HNR), length of fruiting branch (LFB), number of vegetative branches (NVB) and average boll retention at the first position of the fruiting branches (RP1). We identified two ideotypes that yielded better than the others: (i) Mar 88-214 performed well under late planting–high stand density conditions and was characterized by low vegetative growth and early flowering onset, a short flowering period and low RP1; (ii) H 279-1 performed especially well under early planting–low stand density conditions and was characterized by high vegetative growth, late flowering, long EFT and high RP1. We propose a breeding strategy for both ideotypes based on seven indicators with high heritability (FF, HH, HNR, and LFB) or medium heritability (NVB, EFT, and RP1).

2007 ◽  
Vol 43 (2) ◽  
pp. 173-182 ◽  
Author(s):  
EMMANUEL SEKLOKA ◽  
BERNARD HAU ◽  
ERIC GOZÉ ◽  
SYLVIE LEWICKI ◽  
GRÉGOIRE THOMAS ◽  
...  

Effective flowering time in Gossypium hirsutum cotton plants was studied with the aim of enhancing decision making on the best varieties to plant according to the planting date under rainfed cropping conditions. Trials were conducted at two sites in a cotton-growing area of Benin in 2002 and 2003. A split-split plot design with three replicates was used to compare 10 cotton varieties, with different growth cycle lengths and morphology, at three stand densities (42 000, 125 000, 167 000 plants ha−1) and two planting dates (standard planting in June and late planting). The flowering period was characterized by the mean first flower opening date (FF), which is an indicator of flowering earliness, and by the opening date of the last flower giving rise to a first-position boll on fruiting branches (LFP1). Effective flowering time (EFT) was calculated as the difference between LFP1 and FF. EFTs differed markedly in the 10 cotton varieties tested and this parameter could not be predicted on the basis of flowering earliness. Late planting and high planting rates delayed first-flower opening, accelerated last-boll development and reduced the effective flowering time. This latter factor should be taken into account in cotton breeding programmes so that varieties adapted to local rainfall constraints can be recommended to growers while also enhancing crop management sequences.


1998 ◽  
Vol 130 (4) ◽  
pp. 451-462 ◽  
Author(s):  
D. ROUSSOPOULOS ◽  
A. LIAKATAS ◽  
W. J. WHITTINGTON

The growth and development of cotton was studied on cotton plants grown in pots in growth rooms under constant day/night temperature (C) and varying temperature regimes throughout the day and/or night (V) The V-treatments had a common mean temperature of 22°C. The objectives were to determine the thermal requirements of three cultivars and to observe the extent of genotype×thermal environment interactions throughout the entire growth period.Vegetative growth was found to be almost exclusively time and temperature dependent, varietal differences being largely insignificant. Plant material was found to accumulate four times faster under the warmest C-regime, which was 7°C warmer than the coolest. The C-treatments caused variation in the number and size of lateral shoots and leaves, causing leaf area to be larger at the squaring stage in cool environments but at maturity in warm regimes. Relatively cool nights lowered the position of the first floral or fruiting branch, whereas warm days shortened flowering intervals and thus promoted earliness. However, the effect of temperature in altering the position of the first floral branch seems to be less important than its effect on the shedding of early squares.The effects of fluctuating temperature (V) on vegetative growth and earliness were similar to those from constant temperature environments. Growth and development rates were low in the low minimum V-regimes, especially when the maximum temperature was also low. Temperature variation affected vegetative growth to a greater extent in the early than in the later stages of development. At squaring, leaf area and dry weight were lowest under the regime with the highest minimum and maximum temperatures. Later on, only leaf area at flowering and total dry weight at maturity significantly differed between treatments. High maximum or minimum temperatures produced effects similar to a higher or lower mean temperature, respectively. The low minimum raised the node number of the first floral or fruiting branch, whereas in the case of boll dry weight it acted in the same way as a further drop in temperature, decreasing the weight, regardless of the maximum temperature. Boll period was affected mainly by the temperature variation itself rather by than the type of variation.The inverse of time to a certain stage and the corresponding mean temperature were linearly related and allowed threshold temperatures (T0) and thermal time requirements to be estimated. T0=12°C, except for the initial stage, when it was lower. A cotton growing season cooler on average by only 1°C will considerably delay maturity.


1974 ◽  
Vol 25 (5) ◽  
pp. 723 ◽  
Author(s):  
RJ Lawn ◽  
DE Byth

Vegetative and reproductive development of a range of soya bean cultivars was studied over a series of planting dates in both hill plots and row culture at Redland Bay, Qld. Responses in the extent of vegetative and reproductive development were related to changes in the phasic developmental patterns. The duration and extent of vegetative development for the various cultivar-planting date combinations were closely associated with the length of the period from planting to the cessation of flowering. Thus, vegetative growth was greatest for those planting dates which resulted in a delay in flowering and/or extended the flowering phase. Similarly, genetic lateness of maturity among cultivars was associated with more extensive vegetative development. Seed yield per unit area increased within each cultivar as the length of the growing period was extended until sufficient vegetative growth occurred to allow the formation of closed canopies under the particular agronomic conditions imposed. Further increases in the length of the period of vegetative growth failed to increase seed yield, and in some cases seed yields were actually reduced. Biological efficiency of seed production (BE) was negatively correlated with the length of the vegetative growth period. Differences in BE among cultivar-planting date combinations were large. It is suggested that maximization of seed yield will necessitate an optimum compromise between the degree of vegetative development and BE. Optimum plant arrangement will therefore vary, depending on the particular cultivar-planting date combination. ___________________ \*Part I, Aust. J. Agric. Res., 24: 67 (1973).


Euphytica ◽  
2007 ◽  
Vol 163 (2) ◽  
pp. 167-175 ◽  
Author(s):  
Naohiro Uwatoko ◽  
Atsushi Onishi ◽  
Yuji Ikeda ◽  
Manabu Kontani ◽  
Atsushi Sasaki ◽  
...  

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 554d-554
Author(s):  
Millie S. Williams ◽  
Terri Woods Starman

Photoperiod requirements are important for optimum flower development, decreasing production time, year-round flowering, and/or for increasing vegetative growth necessary in stock plant production. The photoperiodic responses were determined for 24 vegetatively propagated specialty floral crops. Each plant species was grown at 8-, 10-, 12-, 14-, and 16-h photoperiods. Photoperiods were provided by 8 h of sunlight, then pulling black cloth and providing daylength extension with incandescent bulbs. Data collected included time to flower, flower number, and vegetative characteristics. Evolvulus nuttallianus `Blue Daze', Heliotropium arborescens `Fragrant Delight', and Orthosiphon stamineus `Lavender' were facultative short-day plants with respect to flowering. Time to flower increased as photoperiod increased. Duranta repens `Blue', Verbena hybrid `Tapien Lavender', and Verbena peruviana `Trailing Katie' were facultative long day plants with respect to flowering. Days to visible bud and first open flower decreased as photoperiod increased. Argeranthemum frutescens `Sugar Baby', Scaevola aemula `Fancy Fan Falls', and Portulaca hybrid `Apricot' had increased flower number as photoperiod increased from 8- to 16-h, although time to first flower initiation was not affected. Abutilon hybrid `Apricot', Duranta repens `Blue', Evolvulus nuttallianus `Blue Daze', Lotus berthelotii `Parrot's Beak', Lysimachia nummularia `Aurea Creeping Golden', Rhodanthe anthemoides `Milkyway', and Scaevola aemula `Fancy Fan Falls' had increased vegetative growth as photoperiod increased. All other species studied were day-neutral with regard to flowering and vegetative parameters.


Weed Science ◽  
2004 ◽  
Vol 52 (6) ◽  
pp. 905-912 ◽  
Author(s):  
Marie-Josée Simard ◽  
Anne Légère

Many conditions need to be satisfied for gene flow to occur between a transgenic crop and its weedy relatives. Flowering overlap is one essential requirement for hybrid formation. Hybridization can occur between canola and its wild relative, wild radish. We studied the effects of wild radish plant density and date of emergence, canola (glyphosate resistant) planting dates, presence of other weeds, and presence of a wheat crop on the synchrony of flowering between wild radish and canola (as a crop and volunteer). Four field experiments were conducted from 2000 to 2002 in St-David de Lévis, Québec. Flowering periods of wild radish emerging after glyphosate application overlapped with early-, intermediate-, and late-seeded canola 14, 26, and 55%, respectively, of the total flowering time. Flowering periods of early-emerging wild radish and canola volunteers in uncropped treatments overlapped from mid-June until the end of July, ranging from 26 to 81% of the total flowering time. Flowering periods of wild radish and canola volunteers emerging synchronously on May 30 or June 5 as weeds in wheat overlapped 88 and 42%, respectively, of their total flowering time. For later emergence dates, few flowers or seeds were produced by both species because of wheat competition. Wild radish density in canola and wild radish and canola volunteer densities in wheat did not affect the mean flowering dates of wild radish or canola. Increasing wild radish density in uncropped plots (pure or weedy stands) hastened wild radish flowering. Our results show that if hybridization is to happen, it will be most likely with uncontrolled early-emerging weeds in crops or on roadsides, field margins, and uncultivated areas, stressing the need to control the early flush of weeds, weedy relatives, and crop volunteers in noncrop areas.


2014 ◽  
Vol 14 (1) ◽  
pp. 1-10 ◽  
Author(s):  
T. F. Adaramola ◽  
M. A. Sonibare ◽  
A. Sartie ◽  
A. Lopez-Montes ◽  
J. Franco ◽  
...  

The literature in recent times lacks adequate report on the utilization and genetic improvement programmes on Dioscorea dumetorum. Despite the wide application of this yam species in agriculture and medicine, it suffers neglect while other species are becoming increasingly popular. Therefore, it is pertinent to focus on research that will bring this species to the limelight. The aim of the present study was to evaluate the ploidy levels, morphological traits and secondary metabolite profile of 53 accessions of D. dumetorum from six countries in West and Central Africa. Ploidy levels were determined using flow cytometry. Overall, 18 morphological traits were recorded from the above- and underground parts of the plant. The 53 accessions were subjected to statistical analyses using the data on ploidy levels, morphological traits and qualitative phytochemical screening. A total of 15 accessions from the generated clusters were selected for thin layer chromatographic and quantitative phytochemical analyses. The analyses revealed diploid (2x) and triploid (3x) levels in these accessions. The pruned dendrogram derived from agglomerative hierarchical clustering based on the distance matrix revealed three main groups, showing a relationship between sex and ploidy level in the accessions and exhibiting sufficient cluster variability that may be important in designing breeding programmes. The crop was also shown to possess metabolites such as alkaloids, saponins and flavonoids, which are known to be useful in the application of phytomedicine. Genetic variability observed among the yam accessions in this study can be used for breeding purposes and to broaden the genetic basis of the crop for efficient utilization of the genetic potential possessed by this species.


Genome ◽  
2013 ◽  
Vol 56 (5) ◽  
pp. 289-294 ◽  
Author(s):  
Mebeasealassie Andargie ◽  
Remy S. Pasquet ◽  
Geoffrey M. Muluvi ◽  
Michael P. Timko

Flowering time is a major adaptive trait in plants and an important selection criterion in the breeding for genetic improvement of crop species. QTLs for the time of flower opening and days to flower were identified in a cross between a short duration domesticated cowpea (Vigna unguiculata (L.) Walp.) variety, 524B, and a relatively long duration wild accession, 219-01. A set of 159 F7 lines was grown under greenhouse conditions and scored for the flowering time associated phenotypes of time of flower opening and days to flower. Using a LOD threshold of 2.0, putative QTLs were identified and placed on a linkage map consisting of 202 SSR markers and four morphological loci. A total of five QTLs related to the time of flower opening were identified, accounting for 8.8%–29.8% of the phenotypic variation. Three QTLs for days to flower were detected, accounting for 5.7%–18.5% of the phenotypic variation. The major QTL of days to flower and time of flower opening were both mapped on linkage group 1. The QTLs identified in this study provide a strong foundation for further validation and fine mapping for developing an efficient way to restrain the gene flow between the cultivated and wild plants.


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