Gametocidal properties of RH-531, RH-532, RH-2956, and RH-4667 on spring wheat (Triticum aestivum L.)

Summary Several chemicals were evaluated for their gametocidal properties to control pollination in hybrid wheat (Triticum aestivum L. em Thell.) seed production. In a preliminary study, four chemicals were applied to three cultivars of spring wheat at two application times. RH-532 was the most effective of the four gametocides, reducing fertility to a 0 10% level for all three cultivars.In a second experiment, RH-532 was applied to one cytoplasmic male-sterile and three normal spring wheats at four rates (0.56, 1.12, 2.24, and 4.48 kg/ha) and at two times of application. Alternate strips of pollinator were planted throughout the experiment. All treatments decreased fertility. plant height, and spike length of the three normal wheats. RH-532 did not inhibit spike emergence of two semidwarf cultivars or one of conventional height. Cultivars did not respond similarly to treatments.Yields of cross-pollinated seed were only 1 21% of the normal yield when fertility levels on treated plants reached 0 10%. Hybrid seed content of the harvested seed ranged from 2 55%. On the treated male-sterile line, yield was significantly reduced in comparison with the open-pollinated check. Inhibitory properties of this chemical suppressed the fertilization potential of the female as well as inducing male sterility.The differential response of genotypes to treatments indicates that cultivars should be screened for male and female sensitivity to this chemical. If differential sensitivity is found, breeding and selection to improve this trait may be possible. Different environmental conditions may alter the response of cultivars to this chemical, with less effect on the female structures.Published with the approval of the Director, North Dakota Agricultural Experiment Station, as journal article No 71a.     

Genetic Variation for Seed Yield in Perennial Ryegrass (Lolium perenne L.)

In perennial ryegrass seed yield is low and unreliable and little is known about the seed-yielding capacity of different cultivars. Therefore, genetic variation for seed yield was studied for therefore, genetic variation for seed yield was studied for three years at two locations. Twelve trials consisting of drilled plots of nine diploid, late-flowering cultivars in four replications were harvested for seed. Significant gentic differences for seed yield and seed weight weight were detected. The ranking of the cultivars for seed yield differed from that for seed weight. The levels of seed yield and seed weight were affected by such environmental factors as year, soil type and crop production year, but interactions of these factors with cultivars were generally not significant. Variation in seed yield was more related to variation in seed number than to variation in seed weight. There were no significant cultivar differences for yield stability. The highest yielding cultivar was superior over a wide range of environments and the seed yield of the poorest cultivar was on average only 64% of that of the best cultivar.     

Path analysis of the relationships between seed yield and some morphological and phenological traits in safflower (Carthamus tinctorius L.)

Path analysis was performed on plant characters of six safflower genotypes grown in a two year field experiment to determine for seed yield, the direct and indirect effects of the following traits: total biomass, stem yield, number of primary branches/plant, number of secondary branches/plant, number of seeds/m², number of seeds/capitulum, number of capitula/plant, capitulum diameter, 1000-seed weight, seed weight/capitulum, distance between ground level and the first fertile branch, plant height, number of days to the beginning of branching, number of days to the beginning of flowering, number of days to 50% flowering, number of days to full flowering and flowering duration. Seed yield was significantly correlated with the following traits: total biomass, stem yield, capitulum diameter, 1000-seed weight, seed weight/capitulum, distance between ground level and the first fertile branch, number of days to the beginning of branching and flowering duration. Total biomass, seed weight/capitulum, distance between ground level and the first fertile branch, 1000-seed weight and flowering duration had substantial direct effects, in that order, on enhancement of seed yield. The significant positive correlation coefficient of capitulum diameter with seed yield resulted from positive indirect effects of total biomass, seed weight/capitulum and 1000-seed weight. Conversely, the significant negative correlations between number of days to the beginning of branching and distance between ground level and the first fertile branch and seed yield resulted from negative indirect effects of the same three traits. Stepwise multiple regression analysis showed that 94% of the total variation in seed yield could be explained by variation in total biomass and by number of days to the beginning of branching (84 and 10%, respectively). Results suggest that total biomass and number of days to the beginning of branching are primary selection criteria for improving seed yield in safflower.     

Phenotypic Variability for Bio-Agronomical Traits in Berseem (Trifolium alexandrinum L.) Populations of the Meskawi Botanical Group

The phenotypic variability and adaptability for bio-agronomic traits in berseem populations (Trifolium alexandrinum L.), was evaluated. The number of genotypes was 32 (26 of southern Italy origin and 6 Egyptian). They were evaluated under field conditions for two years (1989–90) in Foggia (Italy) adopting different cutting regimes: at 7–8th inter-nodes stem length, beginning of flowering, and no cutting. The genotypes of the Italian origin appeared to be better adapted when the cut was applied in the early stage of development, and more productive in seed yield. The Egyptian populations were most productive in forage in the later cuts and had a higher seed weight. The range of variation among the bio-agronomical traits was higher when the cut was applied at early flowering. The traits with wider range of variation were: dry matter, plant height at cut, regrowth at the fourteenth day after cut, tiller density and seed yield. Considering a multiplicative selection index, 6 populations were well adapted and could be used as parents in breeding programs and in extended farm cultivation.     

Variation within improved cultivars and landraces of lucerne in Central Italy

Summary A variety must be distinguishable, uniform, stable and of sufficient productivity to be officially registered. In Italy landraces of lucerne are still widely used because they are characterized by a good persistence and productivity in their area of origin and adaptation.The landrace from Casalina (20 km south of Perugia, Central Italy) has higher dry matter production than many other commercial cultivars. The objective of this paper was to measure the variation of the landrace Casalina and compare it with that of the commonest cultivars available on the market and with some lines selected from the landrace Casalina.The experiment consisted of 11 entries: Casalina, two selections from Casalina (one for high seed yield and one for frequent cuttings), the registered landrace Italia Centrale and 7 registered cultivars. Each entry was represented by 80 genotypes transplanted in the field 60×40 cm apart in a randomized block design with 4 replications. In 1991 the following characters were recorded on a single plant basis: time of first flowering, height, number of shoots and dry matter yield at the first harvest, time of second flowering, leafiness, height, number of shoots and dry matter yield at the second harvest, height, number of shoots and dry matter yield at the third and fourth harvest. Height, number of shoots and dry matter yield at the first harvest, dry matter at the second and third harvest were recorded during the 1992 season.Casalina was as variable as the other entries in 77% of the comparisons; it was more variable in 8% of the comparisons and less variable in 15% of the comparisons. In conclusion, the variation of landrace Casalina is equal to or less than that of registered varieties so that it could be directly registered at the National Registry of Varieties.     

纳罗克非洲狗尾草结实性及适宜收种时间的研究

纳罗克非洲狗尾草在昆明市的抽穗持续时间较长，抽穗高峰期为7月下旬至8月中旬；抽穗后3天内多数花序进入开花期。开花高峰期为始花后第10～15天，开花期前25天内所开小花约占总数的87．5％。开花后10天种子具备正常发芽能力，此时小穗风干物质含量〉60％。始花至成熟种子脱落时间平均为18天，95％种子脱落持续时间平均为45．4d；种子开始脱落后的第15～30天为脱落高峰期，此阶段饱满种子脱落占总数的54．5％。适宜的收种时间为抽穗后第5周。根据本次所有观测结果的变异系数，非洲狗尾草结实性个体间差异极大，是导致种子收获率低的重要原因。     

Physiological responses of chickpea genotypes to terminal drought in a Mediterranean-type environment

Two field experiments were carried out to investigate the effects of terminal drought on chickpea grown under water-limited conditions in the Mediterranean-climatic region of Western Australia. In the first experiment, five desi (small angular seeds) chickpeas and one kabuli (large round seeds) chickpea were grown in the field with and without irrigation after flowering. In the second experiment, two desi and two kabuli cultivars were grown in the field with either irrigation or under a rainout shelter during pod filling. Leaf water potential (Ψ_l), dry matter partitioning after pod set and yield components were measured in both experiments while growth before pod set, photosynthesis, pod water potential and leaf osmotic adjustment were measured in the first experiment only.

In the first experiment, total dry matter accumulation, water use, both in the pre- and post-podding phases, Ψ_l and photosynthesis did not vary among genotypes. In the rainfed plants, Ψ_l decreased below −3 MPa while photosynthesis decreased to about a tenth of its maximum at the start of seed filling. Osmotic adjustment varied significantly among genotypes. Although flowering commenced from about 100 days after sowing (DAS) in both experiments, pod set was delayed until 130–135 DAS in the first experiment, but started at 107 DAS in the second experiment. Water shortage reduced seed yield by 50 to 80%, due to a reduction in seed number and seed size. Apparent redistribution of stem and leaf dry matter during pod filling varied from 0 to 60% among genotypes, and suggests that this characteristic may be important for a high harvest index and seed yield in chickpea.     

Seed yield related to crop development and to yield components in nine cultivars of perennial ryegrass (Lolium perenne L.)

Summary We had previously found differences for seed yield among nine perennial ryegrass cultivars which were not associated with variation for seed weight. To detect the physiological basis of these genetic differences for seed yield, growth analyses were carried out. We related crop development and components of seed yield to seed yield during three years on clay and sandy soil. No significant differences occurred among cultivars for accumulation and partitioning of dry matter or the pattern of tiller production. Seed yield of the cultivars was not associated with ear number or total dry matter yield of the seed crop. Seed yield was more correlated with the number of seeds per unit area than with seed weight. The number of seeds as calculated after harvest from seed yield and seed weight was much lower than the number of seeds as estimated prior to harvest from seed yield components. The number of spikelets differed significantly among the cultivars, but the ranking was different from that for seed yield. The physiological basis of the genetic differences for seed yield is not clear. Implications for breeding perennial ryegrass are discussed.     

Response of four winter wheat cultivars to triallate

Summary Genetic variation among four winter wheat cultivars for response to treatment with triallate was examined. The cultivars showed differential tolerance based on stand count, however, differential tolerance was not seen for any of the other traits examined including visual score, and the mature plant traits, tiller count and yield. Significant effects due to increasing the rate of chemical were observed. An increase in yield was seen at the 0.5 and 1.0 kg/ha rates of triallate. This yield increase was paralleled by trends toward increasing seed number/head and tiller number/unit area. The results indicate that the effect of triallate on wheat has two components. The first component, toxicity, is seen on all cultivars, but the extent of damage varies significantly among cultivars. The second component is positive and leads to an increase in yield without interacting significantly with genotype.     

Characterisation of aromatic rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) germplasm and correlation between their agronomic and quality traits

Eighty-eight aromatic cultivars collected from Maharashtra state were assessed for determinants of kernel quality (kernel size-shape, test weight and aroma) and grain morphology such as awning, lemma and palea characters, pubescence, colour of sterile lemma and apiculus colour. We, report seven cultivars—‘Girga’, ‘Kothmirsal’, ‘Kala bhat’, ‘Chimansal’, ‘Jiri’, ‘Kalsal’ ‘Velchi’ and ‘Kali kumud’ as indigenous to southern India. Of the 69 cultivars characterized for agronomic traits 36 cultivars were exquisite genotypes and possessed one or more superior traits such as early flowering, dwarf stature, higher number of productive tiller per plant; long panicles; higher number of filled grains per panicle and strong aroma. Variability in aromatic cultivars was assessed on the basis of nine traits placed aromatic rice cultivars in five clusters. Number of cultivars in each cluster ranged from 1 to 33. 27 significant correlations were obtained in the physical, agronomic and grain morphology traits. Aroma was found to be negatively associated with days to 50% flowering as well as with filled grains per panicle. However, correlation between panicle length and effective tillers with aroma was not observed. Therefore, to increase the yield, improvement in length of panicle and increasing number of productive tillers in medium or mild scented cultivars would be the best strategy.     

Phenological Development–Yield Relationships in Dry Pea in Semiarid Mediterranean Conditions

Dry pea (Pisum sativum L.) growers in the semiarid Mediterranean region require cultivars that are both early maturing and high yielding. However, negative relationships between these two characteristics limit their simultaneous improvement. A better understanding of the relative importance of the developmental stages in determining yield would assist in pea improvement. Sixteen dry pea cultivars were grown for 2 years under semiarid Mediterranean conditions (Maru, north Jordan) in order to see if differences in growing degree days (GDD) to flowering and GDD from planting to physiological maturity exist and to study their relationships with seed yield. Seed yield was negatively correlated with GDD to maturity, but not significantly correlated with GDD to flowering. Increasing GDD to flowering resulted in higher seed yield, while increasing seed fill duration had little effect. Rapid seed fill rate was positively correlated with seed weight and negatively correlated with seed fill duration. These results indicate that Mediterranean-adapted cultivars would have preflowering periods lasting as long as possible, followed by short seedfill periods. Simultaneous selection for early maturity and a relatively long time to flowering is recommended for the development of early-maturing, high-yielding cultivars adapted to semiarid Mediterranean environments.     

Spaced-plant traits related to seed yield in plots of perennial ryegrass (Lolium perenne L.)

Summary Seed yield in perennial ryegrass is low and selection criteria for high seed production are lacking. Indirect selection in spaced plants would be efficient, but spaced-plant traits need to be identified that correlate with seed yield in drilled plots. Spaced plants were studied of nine perennial ryegrass cultivars with a different seed production when grown in plots. Genotypic variation within cultivars for seed yield components and other traits was assessed in four environments in replicated clonal experiments. Extensive genotypic variation for most traits was present within each cultivar. Based on cultivar means of 25 or 50 genotypes, significant differences among cultivars were found for most traits. Cultivar-year interactions were found for most traits, but no significant cultivar-location interactions were generally found. Spaced-plant traits in general showed poor correlation to corresponding traits in drilled plots. Cultivars with contrasting seed yield in plots could not be distinguished on the basis of their spaced-plant traits and therefore no criteria for indirect selection for seed production in drilled plots could be identified in spaced plants.     

Cytology of seed development related to floret position in perennial ryegrass (Lolium perenne L.)

In seed crops of perennial ryegrass, Lolium perenne L., yields are low and only 15 to 20% of the florets produce a harvestable seed. This study was conducted to determine if seed abortion was a major cause of low floret site utilization (FSU) and therefore of low seed yield in spaced plants. Spikes of four spaced-planted genotypes of perennial ryegrass were harvested and fixed at one-week intervals one to five weeks after the beginning of anthesis. Of a total of 74 spikes, over 13,000 florets were examined with a binocular microscope and 66 whole spikelets were microtome sectioned. The histology of the pro-embryo is presented in relation to the development of the endosperm. In one low yielding, two intermediate and one high yielding genotype, biological FSU was 8, 72, 73 and 63%, respectively. In all genotypes, 90% of the unproductive florets showed ovule degeneration within a few days after flowering. A few florets were sterile or contained a degenerated embryo sac already before flowering and about 5% of the unproductive florets showed seed abortion later than one week after flowering. Within a spikelet, successful fertilization did not decline from the basal to the distal floret. Although in later stages distal florets had slightly less seeds, unproductive florets were found at all floret positions. Biological FSU decreased mainly by ovule degeneration shortly after flowering. In spaced plants, seed abortion was not important to low seed yield.     

Effect of Phenological Stages on Plant Dry Matter Partitioning and Seed Production in Berseem (Trifolium alexandrinum L.)

Berseem clover ( Trifolium alexandrinum L.) is an annual forage crop widely grown in Mediterranean environments. Dry matter partitioning in the leaf, stem and root and seed production of three populations of Egyptian as well as Italian origin were evaluated under four cutting regimes. The cutting treatments were applied to the plants at different stages of plant development: at the fourth (A) and eighth nodes elongation (B), at early flowering (C) and physiological maturity of seeds (D), After herbage, harvest plants were utilized for seed yield and evaluation of its seed yield components. Higher dry matter and seed yield was obtained in treatments D and B, respectively. In the other treatments, dry matter content was lower than in treatment D and related to the phenological development of the plant. Dry matter content in the root was higher when the cut was applied at early flowering. Cutting regimes influenced plant mortality, with the number of dead plants increasing from the cut applied in early (A) to that in the final treatment (D). Cuts applied at early stage of development depleted root reserves causing plant death. This peculiarity could be a tool for selecting populations with higher persistence and with a more tolerant physiological response to stress imposed by cuts. The populations of Egyptian origin, in comparison with the Italian ones, were more productive in dry matter in the early stage of growth and in all treatments were higher in seed weight.     

Improved seed yield in perennial ryegrass (Lolium perenne L.) from two generations of phenotypic selection

Two generations of recurrent phenotypic selection for seed yield per plant under controlled pollination were carried out to combine improved seed yield with improved forage grass performance in perennial ryegrass (Lolium perenne L.). Selected and unselected varieties (AberDartand AberElan respectively) and control varieties were grown for seed in pots in a glasshouse experiment and in two field plot experiments over 5 harvest years. Seed yield components and seed yield were measured. Significant improvements in seed yield of the selected AberDart over the unselected AberElan were observed both in individual plants grown in the glasshouse and in field plots. Detailed observations of the individual components of seed yield showed that the increased seed yield of AberDart can be attributed to a higher proportion of ovules forming seeds (% seedset), greater seed number per tiller and more reproductive tillers per plant. This improvement in seed yield of AberDart was also observed when it was grown in field plots with AberElan, experimental selection lines and commercial varieties. AberDart produced more seeds per tiller than the other commercial varieties and selection lines studied. The implication of this approach for the breeding of perennial ryegrass varieties that combine good agronomic performance and acceptable seed yields is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparative study on growth and development of some accessions of local Germplasm of Bambara groundnut (<Emphasis Type="Italic">Vigna subterrenea</Emphasis> L. Verdc.) of Nigeria in two cropping seasons

Two field experiments were conducted in April (early cropping) and August, (late cropping) 2007 at the Department of Crop Science Research Farm, University of Nigeria, Nsukka, to evaluate the agronomic and yield attributes of 13 cultivars of bambara groundnut. The results obtained showed that planting dates had significant effects (P < 0.05) on all traits measured. Significant cultivar and cultivar x planting date interaction effects were observed for days to 50% flowering. The principal component analysis showed that the first three components accounted for 85.18 and 86.81% of the total variation in the early and late planting, respectively. The traits representing the cultivars along the first principal axis were number of pods per plant and seed weight per plant for the early planting and number of leaves per plant and seed weight per plant in the late planting. Cultivars were differentiated on the basis of number of flowers per plant and plant height for the early planting and days to emergence for the late planting along the second principal axis. The cluster plot revealed that the 13 bambara groundnut cultivars were grouped into three clusters at both the early and late planting dates. In the early planting, the cultivars in cluster I are associated with high number of flowers, number of pods, and plant height, while cluster II cultivars flowered earlier and had good pod and seed yield. However, cluster III cultivars performed poorly in all the traits evaluated. During the late planting, the cluster I comprised early flowering cultivars while cluster II comprised cultivars with good vegetative growth, high number of pods per plant and seed weight per plant. Cluster III cultivars are early emerging and early flowering but have poor seed yield. The correlation coefficient for seed weight per plant was highly significant and positive with number of leaves per plant, plant height, number of flowers per plant and number of pods per plant indicating that increase in these traits will ultimately increase seed weight per plant. Thus, these traits could be considered as major seed yield contributing traits that could be given significant recognition during selection.     

Consistent Variation Across Soil Types in Salinity Resistance of a Diverse Range of Chickpea (Cicer arietinum L.) Genotypes

Chickpea is considered sensitive to salinity, but the salinity resistance of chickpea germplasm has rarely been explored. This study aimed to (i) determine whether there is consistent genetic variation for salinity resistance in the chickpea minicore and reference collections; (ii) determine whether the range of salinity resistance is similar across two of the key soil types on which chickpea is grown; (iii) assess the strength of the relationship between the yield under saline conditions and that under non‐saline conditions; and (iv) test whether salinity resistance is related to differences in seed set under saline conditions across soils and seasons. The seed yield of 265 chickpea genotypes in 2005–2006 and 294 cultivated genotypes of the reference set in 2007–2008 were measured. This included 211 accessions of the minicore collection of chickpea germplasm from the International Crops Research Institute for the Semi‐Arid Tropics (ICRISAT). The experiments were conducted in a partly controlled environment using a Vertisol soil in 2005–2006 and an Alfisol soil in 2007–2008, with or without 80 mm sodium chloride (NaCl) added prior to planting. In a separate experiment in 2006–2007, 108 genotypes (common across 2005–2006 and 2007–2008 evaluations) were grown under saline (80 mm NaCl) and non‐saline conditions in a Vertisol and an Alfisol soil. In 2005–2006 in the Vertisol and 2007–2008 in the Alfisol, salinity delayed flowering and maturity, and reduced both shoot biomass and seed yield at maturity. There was a large variation in seed yield among the genotypes in the saline pots, and a small genotype by environment interaction for grain yield in both soil types. The non‐saline control yields explained only 12–15 % of the variation of the saline yields indicating that evaluation for salinity resistance needs to be conducted under saline conditions. The reduction in yield in the saline soil compared with the non‐saline soil was more severe in the Alfisol than in the Vertisol, but rank order was similar in both soil types with a few exceptions. Yield reductions due to salinity were closely associated with fewer pods and seeds per pot (61–91 %) and to lesser extent from less plant biomass (12–27 %), but not seed size. Groups of consistently salinity resistant genotypes and the ones specifically resistant in Vertisols were identified for use as donor sources for crossing with existing chickpea cultivars.     

Genotype × cropping system interaction in climbing beans (Phaseolus vulgaris L.) grown as sole crop and in association with maize (Zea mays L.)

The selection of cultivars for the predominant cropping systems of small farms in the tropics depends to a large extent on the information obtained by testing their performance across the different systems. The main objective of this experiment was to measure the genotype × cropping system (G × CS) interaction for yield and selected agronomic traits of climbing beans (Phaseolus vulgaris L.) grown as sole crop and intercropped with two morphologically contrasting maize (Zea mays L.) cultivars. A secondary objective was to identify the most efficient and productive bean–maize intercrop combinations. Seven climbing bean genotypes were grown as sole crop and intercropped with two maize varieties, BH 140 (Mix. 1) and Guto (Mix. 2), in a factorial arranged Randomized Complete Block Design with three replications at Bako Agricultural Research Center in western Ethiopia. Main effects due to genotype and cropping system (except days to flowering) were significant for all bean traits considered. The genotypes × cropping system interaction terms were also significant for the number of seeds per pod, 100-seed weight, harvest index and seed yield. While bean seed yield significantly correlated with the number of seeds per pod (in Mix. 1) and with harvest index (in both mixtures), positive and significant correlations occurred with the number of pods per plant and 100-seed weight under sole cropping system. The correlation between bean seed yields of Mix. 1 and Mix. 2 and between Mix. 2 and sole crop were positive and significant. No such relationship was found between Mix. 1 and sole crop. The results suggest that selection of suitable climbing bean cultivars for intercropping with maize varieties predominantly grown in the area should be made under the associated culture of the two crops. Intercropping contributed to a significant reduction in seed yield of the bean genotypes due mainly to its adverse effects on the numbers of pods per plant and seeds per pod. The index tLER₁ identified most bean–maize genotype combinations of Mix. 2 as biologically more efficient system than Mix. 1. On the other hand, tLER₂ values of more than 1.00 for all treatments of Mix. 2 demonstrated higher overall productivity of the intercrop system when the bean genotypes were grown in association with a late-maturing and high yielding maize hybrid BH 140.     

Genetic and environmental variation in architecture and yield components in determinate white lupin (Lupinus albus L.)

Summary Determinate architecture is of great interest for lupin production in Europe but the extent of genetic and environmental variation in the structure and yield of determinate lupins must be evaluated. Forty-three genotypes of determinate autumn-sown white lupin were studied in four environments in France in 1991/92 and 1992/93. Wide variation was observed for phenological (dates of mainstem and branch flowering, date of end of flowering and date of maturity), morphological (numbers of branch orders, branches and leaves) and seed characters (seed yield, mean seed weight, number of seeds/m²). Both genetic and environmental effects contributed to the observed variation. Heritabilities were high for all characters, and the interaction between genotype and location effects was low. There were significant positive correlations of flowering dates with vegetative plant development including the number of branches, number of leaves and number of branch orders. Seed yield and phenological and archtectural characters were significantly correlated. Distribution of yield on the vegetative orders showed important variations according the genotype, and the variations were related to variation for the architecture. There are possibilities for yield improvement using morphological characters in determinate autumn-sown lupin.