Osmoregulative capacity in birdseed millet under conditions of water stress. I. Variation in Setaria italica and Panicum miliaceum

Experiments involving 14 accessions of Panicum miliaceum L. (Proso millet) and 11 accessions of Setaria italicaL. (Foxtail millet) have demonstrated variability in the degree of osmoregulative capacity among these accessions. Birdseed millet is generally claimed to be sensitive to drought stress, apparently because of a shallow root system. Accessions with high osmoregulative capacity demonstrate at least some drought tolerance. Osmoregulative capacity was measured on flag leaves of headed millet plants in pots undergoing water stress in a controlled environment chamber. Osmoregulative capacity was determined from the relationship between osmotic potential and leaf water potential; and the logarithmic relationship between osmotic potential and relative water content. The group of accessions of S. italica showed an overall level of osmoregulative capacity which was greater than that observed for the group of P. miliaceum accessions. Four accessions of S. italica(108042, 108463, 108541 and 108564) and one accession of P. miliaceum (108104)demonstrated high osmoregulative capacity. Differences of 1.05 MPa or more between observed and estimated osmotic potential were found at relative water contents of80 % among these accessions. The extent of osmoregulative capacity was associated with osmotic potential at full turgor and the rate of decline in osmotic potential as leaf water potential declined. This revised version was published online in August 2006 with corrections to the Cover Date.     

Grain yield and its components in spring barley under row and hill plot conditions

Twenty homozygous barley lines were grown in row and hill plots at two locations in Ontario in 1973. The hill plots were of two spacings –30×30 cm and 45×45 cm between hills. Within each spacing, three seeding rates were used i.e. 15, 25 and 35 seeds per hill. Grain yield and three of its components, namely; number of seeds per spike (NSS), number of spikes per plot (NSP) and seed weight (SW) were studied. It was concluded that both NSS and SW could be evaluated in hill plots. NSS was found to be an important component of grain yield and its relationship with grain yield was unaffected by plot types and locations. SW also remained unaffected by plot types and seeding rates but as a component of grain yield it was the least important of the three components measured. The correlation between SW and grain yield could be changed by locations. NSP was as important as NSS as a component of grain yield, and was highly correlated with grain yield. Unlike NSS, NSP could not be efficiently evaluated in hill plots since its correlation between row and hill plots was generally lower.     

Traditional maintenance and multiplication of foxtail millet (Setaria italica (L.) P. Beauv.) landraces in China

Summary Foxtail millet (Setaria italica L. P. Beauv.) has been one of the most important cereals in northern China. A large number of landraces have formed under natural and man-made selection since domestication. Farmers in China have developed various traditional methods of maintenance and multiplication of foxtail millet seeds for next generation. Panicle selection was often done in fields. The selected seeds were generally stored at dry places. Archaeological and historical evidence of the origin of foxtail millet in China and the geographical distribution of landraces is also presented.     

Selection for yield in Lolium perenne. II. performance of spaced plant selections under competitive conditions

Summary The performance of six lines of perennial ryegrass (Lolium perenne L.) which had been selected for three generations for production under spaced plant conditions were assessed under increasing levels of competition, namely spaced plants, drills, miniplots and large sown plots. Successful selection for yield under spaced plant conditions was not accompanied by comparable production patterns in the alternative managements. The extreme situation occurred in swards where a significant decline in production was encountered. Negative or no relationships were found in the establishment year between spaced plant production and yield in the alternative conditions whereas in the first harvest year positive correlations occurred between spaced plants, drills and miniplots and only the latter with plots. These varying patterns of performance are considered in relation to the prediction of sward behaviour and the appropriate environment for selection.INIA. CRIDA 01, La Coruna, Spain.     

Variation in flower abscission of peppers under stress shading conditions

Summary Seedlings from 77 accessions including inbreds, F₁ hybrids and seven F₂ populations were exposed to approximately 60% shading for 35 days following transplanting into the field.Most of the lines did not set fruit under the shading due to heavy abscission of flowers. A few exceptional lines, hybrids and F₂ segregants showed resistance to abscission and set normal fruits under the shading regime. This procedure is suggested for screening against stress-induced flower abscission. An association is suggested between resistance to shading and to high temperatures and its genetic control.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel No. 1209-E, 1993 series.     

Genotypic variation for root pulling resistance in potato and its relationship with yield under water-deficit stress

Summary An extensively distributed root system may reduce the probability of crop failure during periods of restricted water supply. A quantitative measure of root distribution in the soil profile, i.e. pulling resistance of roots (PR), was tested at two moderately droughted tropical field sites. A total of 250 genotypes were evaluated for PR, 45 days after planting and for tuber yield at harvest at separate sites and years. The need to use genotypes adapted to a specific location for comparisons, across sites or seasons was shown by the results of a random analysis of variance model partitioning across site-season, location, and year effects for PR and tuber yield.A combined PR and growth analysis on 31 early-maturing clones, 7 of which had tubers at the time of sampling, gave significant correlations between PR and root length, dry weight of pulled and residual roots, plant height, number of stems, and in the case of the 7 genotypes with tubers, tuberlet weight and number. A regression model to predict PR based on growth analysis data is presented. Neither tuberlet weight nor number contributed significantly to the prediction once root characters and vigour-related characters were incorporated. Variation for PR among clones was significant and the means ranged from 0 kg/plant to 37 kg/plant during the 3 trials. High PR was evident in both early and late maturing clones. Drought resistance (DR), defined as high yielding ability and high PR under water deficit conditions, of the clones Huinkul and MS-35.22.R was superior to that of the high-yielding and adapted LT-7 check, while moderate levels of DR were confirmed for the clones BR-63.15, Cruza 27, Haille, and MEX-21. Tuber yield and PR under moderate drought were significantly correlated (r=0.569^***), which suggests that the PR method can be utilized to assist in the selection of high-yielding, drought resistant, potato genotypes adapted to tropics.     

Adaptation and yield stability of selected lines of Lathyrus spp. under rainfed conditions in West Asia

Summary Sixteen promising lines (selections) of Lathyrus spp. (chicklings), comprising 11 L. sativus, four L. ochrus, and one L. cicera, were evaluated under rainfed conditions in Syria. Two locations in each of four years were treated as separate environments, to give eight environments altogether. Genotype x environment (G×E) interactions were analysed using linear regression.There was considerable variation in herbage and seed yields within both lines and environments. Genotype x environment interactions were present for both herbage and seed yields; a little over half was accounted for by the linear regression. The non-linear component was also significant, although it was smaller than that of the linear component.The most stable herbage and seed yields were obtained from L. sativus. Two selections, 347 and 311, origmating from Syria and Turkey respectively, combined both high herbage and seed yields with wide adaptation and stability, and could be considered the most widely adapted lines. Other lines were identified as suitable for favourable and unfavourable environments; in particular, all four lines of L. ochrus have great potential in frost-free climates. The importance of genotype x environment interactions in future breeding strategies is discussed.     

Molecular identification of Pm12-carrying introgression lines in wheat using genomic and EST-SSR markers

The traditional process of obtaining maize hybrids involves the generation of inbred lines through successive generations of selfing and subsequent testcrosses in order to identify the best combining ability by allelic complementation. A fast alternative to obtain inbred lines is to induce the formation of haploids followed by chromosome doubling. However, even with the aid of haploid-inducing genetic sources, this strategy has not been widely used in maize breeding programs, partly due to difficulties inherent to haploid generation and identification. In order to evaluate the possibility of using dihaploids to generate homozygous maize tropical lines, we used the androgenetic haploid inducer line W23 as a female parent in crosses with the tropical single-cross hybrid BRS1010. Within the progeny of these crosses, 462 seeds were phenotypically selected as putative haploids by the purple-colored endosperm and colorless embryo conditioned by the R1-nj gene. Among these, only four individuals were confirmed as being haploids using SSR markers, chromosome counting and flow cytometry, showing that the phenotypic marker was not efficient in detecting haploids in the tropical maize genotype used. All four haploids as well as some diploid plants presented reduced size, corroborating the difficulties for haploid identification by phenotypic evaluation. Genetic diversity analysis revealed by SSR markers divided the haploids in two groups represented by flint and dent maize inbred lines, which could be helpful in identifying complementary dihaploid lines. The present article demonstrates that a combination of haploid production and SSR fingerprinting is a feasible strategy for maize hybrid development in tropical germplasm.     

Response to selection for grain yield and harvest index in F2, F3 and F4 derived lines of two wheat crosses

Summary Aspects of selection for yield and harvest index were investigated by simulating selection using data from random pedigreed F₂, F₃, F₄ and F₅ derived lines from two crosses grown in plots at two sites over two years.Improvement in yield through selection was obtained when the response was measured at the same site and in the same year as the selection. Selecting the best 10 per cent of F₂ to F₄ derived lines gave F₅ derived lines that outyielded random selections by 19 to 53 per cent for one cross and 5 to 23 per cent for the second cross. These lines were 41 to 50 per cent better than the mid-parent in one cross, but were less than the mid-parent in the other cross.However, the response to selection when measured in a different year was little better than random selection. The effect of different sites also reduced the effectiveness of selection.Selection of harvest index in early generations for improvement of yield was ineffective when response was measured at the same site in the same year, or in different years.Contrary to some theoretical proposals, the same improvement in yield was obtained by selecting in early or late generations. While high yielding genotypes may be lost by delaying selection, this is counteracted by the better predictive value of late generations due to their greater homozygosity and homogeneity.     

Callus induction and plant regeneration from anther and inflorescence culture of Sorghum

Summary Twenty-five inbred lines, including grain and forage types from the USA and China, two hybrids, one Sorghum almum, and one Parasorghum (S. versicolor) were tested for their response to anther culture. Three nutrient media were effective in inducing anther calli from six cultivars (Xin White, TX 403-TSB, DDY Sommer Milo, TX 2779, Brawley, and Spur Federal) and one was effective for plant regeneration for one cultivar, Xin White. Averaged over media, callus induction frequency (number of calli per 100 anthers) was highest in cultivars Xin White and TX 403-TSB (6.7 and 3.9%, respectively). The means of cultivars for media C17-2 and Ms-t-z-2, 4.3 and 3.2%, respectively, were superior to that for medium 85D3-2 (0.1%). Expressed as an average of the six cultivars and three media the mean calli induction frequency was 2.6%; however, differential responses of genotype and medium were noted. Among the 10 regeneration media tested, medium MS-d-4 containing Murashige and Skoog basal components plus 2.0 mg/l indole-3-acetic acid (IAA) and 2.5 mg/l kinetin was the most effective for plant regeneration. Numbers of albino plants and calli developing only roots increased directly with callus-induction time, whereas the frequency of plant regeneration decreased. Regenerated plants had varied numbers of chromosomes in root tip cells: 10, 15, 20, 40, and 60. The 29 regenerated plants that reached maturity, however, were highly fertile and contained only 10 bivalents in pollen mother cells. Normal chromosome number and behavior for the regenerated plants suggest that induced calli originated from cells other than microspores. However, spontaneous chromosome doubling in microspore-derived haploids may occur. The appearance of albinos also implies that haploids may have been produced from anther culture.Joint contribution of the Dept. of Agronomy and USDA-ARS, Kansas Agricultural Experiment Station, Manhattan, KS 66506-5501, USA. Contribution no. 88-566-J.     

Effect of d2 dwarfing gene on grain yield and yield components in pearl millet near-isogenic lines

Summary A d₂ dwarfing gene in pearl millet [Pennisetum glaucum (L.) R. Br.] is currently being extensively used for the development of hybrid parents. Its effect on grain yield and yield components is poorly understood. Twelve pairs of tall and dwarf near-isogenic lines developed in the diverse genetic background of three composites were evaluated for grain yield and yield components for 2 years at two locations in southern India. The d₂ gene or the genes linked to it, on an average, reduced plant height by 42%, grain yield by 14%, and head girth by 8% but increased head length and number of tillers per plant by about 5–6%. Large variations were observed among pairs (genetic background) for the difference between tall and dwarf near-isogenic lines for all of the above yield components resulting in no significant difference in five pairs and 17–35% less yield in dwarfs as compared to their tall counterparts in six pairs. Days to 50% flowering and seed weight were least affected by the d₂ gene with the average difference between tall and dwarf groups of near-isogenic lines being of the order of 1–2%. These results indicate that the advantageous effects of d₂ dwarfing gene can be effectively exploited by manipulating the genetic background. The difference between the average grain yields of tall and dwarf groups of near-isogenic lines showed considerable variation across environments with the dwarfs yielding as much as tall group in one environment and up to 30% less than the tall group in the other, thus, indicating that the d₂ gene effect may be substantially modified by the environments.Submitted as JA No. 979 by the International Crop Research Institute for the Semi-Arid Tropics (ICRISAT).     

Comparison of fertility between the F1, F2 and anther derived lines in the crosses of indica/japonica and japonica/indica in rice (Oryza sativa L.)

Summary Response of anthers in in vitro culture was examined in the indica-japonica hybrids of rice (Oryza sativa L.). Significant genotypic differences were observed for callus induction and regeneration among the different interracial hybrids of indica-japonica races. Induction frequency of haploids ranged from 57.7 to 72.9 per cent and doubled haploid androgenic lines ranged from 27.1 to 42.3 per cent in the anther culture of the different hybrids. The indica-japonica hybrids recorded partial pollen grain and spikelet fertility in F1 (29.9 to 41.5% and 19.4 to 48.7% respectively) as well as in F2 (42.7 to 50.6% and 37.1 to 54.4% respectively). In contrast, the androgenic doubled haploid lines recorded significant increase and the pollen grain and spikelet fertility was 76.3 and 78.6 per cent respecitively. The results suggested that the sterility barriers for realising genetic recombinants and fixation of fertile homozygous lines in indica-japonica hybridization programme could be overcome through F1 anther culture technique.Abbreviations BAP Benzyl Amino Purine - 2,4-D 2,4-Dichlorophenoxy acetic acid - MS Murashige & Skoog medium - IAA Indole Acetic Acid     

Stem solidness and its relationship to grain yield in 17 spring wheat crosses

Summary Stem solidness in the wheat plant provides resistance to the wheat stem sawfly, a pest of wheat in Montana and North Dakota, but some agronomists have been concerned that stem solidness might be related to low grain yields. We evaluated 17 spring wheat crosses for stem solidness, grain yield, and other agronomic traits in F₂ through F₄ generations from 1972 to 1975.Highly significant correlation (0.735) and regression (0.731) coefficients between F₂ and F₃ generations verify previous studies showing that stem solidness is highly heritable and that selection in F₂ should be successful. Solid-stemmed F₄ composites yielded more than hollow stemmed composites at Bozeman and equal yields were obtained at Huntley, indicating that stem solidness is not a deterrent to high grain yield.Joint contribution of Federal Research, Science and Education Administration, U.S. Department of Agriculture and the Montana Agricultural Experiment Station, Bozeman, MT 59717. Published with approval of the Director of the Montana Agricultural Experiment Station as Paper No. 815, Journal Series.     

Stability of forage yield and quality in pearl millet hybrids heterogenous for rust resistance

Summary The susceptible pearl millet hybrid Tifleaf 1, the resistant hybrid Tifleaf 2, and two experimental 3-way hybrids with different proportions of resistant and susceptible plants were evaluated for rust resistance and forage yield and quality in 1990, 1991, and 1992. Different environmental conditions were obtained by varying planting date, planting density, and fungicide applications across three years of evaluation in the field. Rust severity of forage was negatively correlated with late season green yield, dry matter yield, in vitro dry matter digestibility, and digestible dry matter yield. The stability across environments of the 3-way hybrids was intermediate between resistant Tifleaf 2 and susceptible Tifleaf 1 for rust severity and the yield and quality measurements negatively correlated with rust severity. Mixtures of resistant and susceptible plants would probably provide greater control of rust than measured in these small-plot experiments. Although a mixture of resistant and susceptible plants appears to provide an alternative to monogenic control of rust in forage pearl millets, identification and utilization of additional sources of resistance would be beneficial to improve the performance of 3-way hybrids.     

A dominant gene in rice for resistance to white-backed planthopper and its relationship to other plant characteristics

Summary The inheritance of resistance to white-backed planthopper, Sogatella furcifera Horvath, was investigated in a rice, Oryza sativa L., cultivar N22. Resistance to the white-backed planthopper in the cross IR30×N22 appears to be governed by a single dominant gene-designated Wbph. The classification for various characteristics of 397 F₃ families of the IR30×N22 cross confirmed earlier results about the monogenic dominant control of resistance to brown planthopper, green leafhopper, and bacterial leaf blight, and about the monogenic recessive control of short stature. Additionally, the genes governing plant height and resistance to white-backed planthopper, brown planthopper, green leafhopper, and bacterial leaf blight were found to segregate independently of each other in these 397 F₃ families.     

Identification of self-incompatibility (S) alleles in Latvian and Swedish sweet cherry genetic resources collections by PCR based typing

The Latvian and the Swedish sweet cherry (Prunus avium L.) genetic resources collections comprise valuable material for breeding. The collections represent local Latvian and Scandinavian genetic resources: semi-wild samples, landraces, and cultivars developed in local breeding programmes, as well as diverse germplasm from the northern temperate zone. The objective of this investigation was to determine which S ₁ –S ₆ alleles are most important in the sweet cherry genetic resources collections and to compare the identified allelic and genotypic frequencies in material of different origin. Accessions in the two collections were screened for the presence of the self-incompatibility (S) S ₁ to S ₆ alleles, using PCR based typing. Significant differences (P < 0.05) between screened collections were found in frequencies of S ₄ and S ₅ alleles. Analysis of allele combinations identified the high occurrence of selections with the S-genotype S ₃ S ₆ in both collections. Compared to the S-allele frequencies published for over 250 sweet cherry cultivars from Western and Southern Europe, the Latvian and Swedish germplasm appeared to have a high frequency of the S ₆ allele in both collections, and a relatively high frequency of the S ₅ allele in Latvian germplasm. This study represents the first comprehensive S-allele screening for the sweet cherry genetic resources collections in Latvia and Sweden. Both sweet cherry collections contain high proportion of accessions adapted to north central European growing conditions, not typical for the majority of the documented sweet cherry genetic resources, which explains differences in certain S-allele occurrence.     

Variance component analysis of plant architectural traits and fruit yield in melon

Summary  A cross was made between a unique highly branched, early flowering line, U. S. Department of Agriculture (USDA) 846-1 (P_1; 7 to 11 lateral branches), and ‘Topmark’ (P₂; 2 to 4 lateral branches), a U.S. Western Shipping melon, to produce an array of 119 F₃ families. Subsequently, a genetic analysis was conducted at Arlington and Hancock, Wisconsin in 2001 to evaluate the segregating progeny for factors likely involved in yield-formation, including days to anthesis, percentage of plants with early pistillate flowering, primary branch number, fruit number and weight per plant, average weight per fruit, percentage of plants with predominantly crown fruit set, and percentage of plants with early maturing fruit. Although, genotype × environment (G × E) interactions were important for some traits (e.g., fruit number and fruit weight), considerable additive and/or dominance variance was detected for all traits. This research provides critical data associated with highly branched melon germplasm including trait correlations and heritabilies (broad- and narrow-sense ranged between 0.28 and 0.91) that used judiciously will allow the development high yielding melon cultivars with early, basally concentrated fruit suitable for once-over or machine harvesting operations.     

Tissue and cell culture as aids to sugarcane breeding. II. Performance and yield potential of callus derived lines

Summary Thirteen callus derivatives from the sugarcane (Saccharum sp. hybrid) varieties F156 and F164 were studied to investigate the potential of tissue culture methods to generate superior germplasm for plant breeding in a field trail conducted at a single location. Comparisons between callus derivatives and donors were made for 9 characters, viz. cane yield, sugar yield, stalk number, length, diameter, volume, density, weight/stalk, and percent fiber. Statistical analyses were run, which involved stepwise multiple regression, broad-sense heritability (H), genetic advance (G). Esterase zymogram of superior callus derivatives was examined. 70–6132 was 32, 34 and 6% higher than its donor (F164) in cane yield, sugar yield and stalk number, respectively. The differences between them for the first two characters reached the 5% probability level. 70–6132 was also higher for these 3 characters than F160, the No. 1 commercial variety, by 20, 16 and 8%, respectively. 70–6136 ranked next only to 70–6132. Its grand means for these 3 characters outdid the parental (F164) means by 21, 24 and 3%, respectively. 70–6069 was significantly higher in stalk diameter and volume than most of the callus derivatives but not higher than its donor (F156). The performances of other derivatives were either similar or inferior to both their donors and F160. Stalk number, stalk length and weight/stalk accounted for 43, 29 and 18% of the variation of cane yield, respectively. H values for the 7 characters (stalk density and percent fiber were not included) ranged from 31 (stalk length) to 66% (stalk volume). G/\-x 100 for the 7 characters ranged from 3.3 (stalk length) to 18.6% (sugar yield). 70–6132 had two bands missing, 70–6069 had two bands more whereas those of 70–6136 showed no visible change, in esterase zymogram as compared with the donors. Due to the improved yield and the genetic changes revealed by the isoenzyme patterns in callus derived lines, tissue culture methods can be used to create superior varieties for agricultural use.     

Stability of bacterial leaf spot resistance in peach regenerants under in vitro,greenhouse and field conditions

Summary Phenotypic stability of bacterial leaf spot resistance in peach (Prunus persica (L.) Batsch) regenerants, either selected at the cellular level for insensitivity to a toxic culture filtrate of Xanthomonas campestris pv. pruni or screened at the whole plant level for resistance to X. campestris pv. pruni, was investigated. A detached-leaf bioassay was used to evaluate the original regenerants again after three years in the greenhouse and also after a two to three year cycle of tissue culture propagation. Peach trees derived through micropropagation from the original regenerants were also evaluated after one to three years growth in the field. Although leaf spot resistance was retained in some regenerants over time in the greenhouse, following in vitro propagation, and under field conditions, resistance was either lost or not expressed in others. Regenerants # 19-1 and #156-6, derived from embryo callus of bacterial spot susceptible Sunhigh, were significantly more resistant than Sunhigh. High levels of resistance were exhibited in greenhouse plants and field-grown trees of regenerant #122-1, derived from embryo callus of moderately resistant Redhaven. This research provides additional evidence that selecting or screening for somaclonal variants with disease resistance is a feasible approach to obtaining peach trees with increased levels of bacterial spot resistance.Abbreviations TC Tissue-Cultured - TF Toxic culture Filtrate     

The evaluation of adult plant resistance to powdery mildew (Erysiphe graminis f.sp. avenae) in transgressive lines of oats

Summary Previously identified segregant lines of oats with levels of adult plant resistance to powdery mildew (Erysiphe graminis f.sp. avenae) better than the resistant parent maintained this high level of resistance in field nurseries over two growing seasons. This enhancement was not expressed on inoculated detached leaves under laboratory conditions where no differences between the more resistant parent cv. Maldwyn and the most resistant segregants was detected. Reduced resistance was not detected in tests where leaf segments of the transgressive lines were inoculated with trained isolates. Problems associated with selecting for adult plant resistance under both field and laboratory conditions are discussed.