Physiological changes during seed development of cuphea

Cuphea (Cuphea viscosissima Jacq. x C. lanceolata W.T. Aiton, PSR23) is a new oilseed being developed in the north-central USA. Cuphea oil is high in medium-chain fatty acids suitable for detergent/cleaner applications and has potential for use in cosmetics. The objectives of this study were to determine the effect of seed development on seed moisture, weight, oil content, fatty acid composition, germination, and vigor. Two thousand cuphea flowers were tagged at anthesis in the field each year at Prosper, ND, in 2004, 2005, and 2006. Each flower that developed into a seed capsule was tagged and labeled with the date of anthesis. Two hundred developed capsules from the labeled flowers were harvested at 3 to 4-day intervals from 5- to 35 days post anthesis corresponding with 37 to 295 growing degree days (GDD). The GDD were calculated using a base temperature of 10 °C. Seed development required approximately 253 GDD or 30 days post anthesis to reach physiological maturity. Maximum seed germination was reached at 33 days post anthesis. Seed oil content increased and oil composition changed as seed matured. Seed oil was high in linoleic and palmitic acids from 0 to 10 days post anthesis and declined thereafter while capric acid began to accumulate at 10 days post anthesis and reached above 70% at physiological maturity.     

Seed physiological maturity in Cuphea

Cuphea (Cuphea viscosissima Jacq. × C. lanceolata f. silenoides W.T. Aiton, line PSR23) is a new crop being developed in the North Central United States, as an industrial oilseed crop. Cuphea PSR23 seed oil is rich in medium-chain-length fatty acids such as capric acid used to manufacture soaps and detergents. The objective of this research was to determine the time when physiological maturity of cuphea seed is reached and how seed development affects seed moisture, weight, oil content, fatty acid content, germination, and seedling vigor. To evaluate seed development, 2000 cuphea flowers were tagged at anthesis in the field at Prosper, North Dakota in 2004 and 2005. Each flower was tagged when open and the position on the main stem or branch was recorded. Two hundred capsules from the tagged flowers were harvested at 3- to 4-d intervals from 5- to 48-d post anthesis (DPA). Seed weight increased as a function of growing degree days (GDD) and the days from anthesis. Physiological maturity occurred when maximum dry seed weight was attained. Seed weight increases followed the Gompertz function with a R² = 0.90 (2004) and R² = 0.95 (2005). All capsules, regardless of their position on the stem, followed the same growth function for seed weight. The maximum dry seed weight estimated by the Gompertz function was 3.61 for 2004 and 3.58 mg seed⁻¹ for 2005. Physiological maturity estimated with a quadratic function occurred at 38 DPA or 270 GDD in 2004. In 2005, physiological maturity occurred at 26 DPA or 265 GDD. As a visual indicator when the capsules split-open seeds inside that capsule are physiologically mature. Seed moisture decreased from 900 g kg⁻¹ at 37 GDD post anthesis to 450 g kg⁻¹ at 319 GDD post anthesis in 2004; however, in 2005 seed moisture decreased from 850 to 81 g kg⁻¹ at 293 GDD post anthesis. Seed germination increased as seed developed and it was 83% when harvested 234 GDD post anthesis. Oil content increased from 98 g kg⁻¹ at 37 GDD post anthesis to 279 g kg⁻¹ 319 GDD post anthesis. Fatty acid composition varied throughout seed development. Seed development for 111 GDD and greater had more than 66% of capric acid (10:0). Cuphea should be harvested after 265 GDD post anthesis when most capsules on the main stem are split-open, have attained maximum seed weight, germination, seedling vigor, and oil content.     

SELECTION FOR SEED RETENTION IN S48 AND S51 TIMOTHY (PHLEUM PRATENSE L.)

Seed shedding was studied in 50 clones each of S5I and S48 timothy during 1961–3. Some clones retained on average during 2 or 3 seasons from 80–90% of their maximum seed weight until 42 days after peak anthesis; this was up to 28% above the varietal mean. The results suggest that clones which retain their seed also produce high yields of seed and of dry matter; they can also be easily threshed.     

SEED PRODUCTION STUDIES ON PERENNIAL RYEGRASS, TIMOTHY AND PRAIRIE GRASS

This paper considers the sequence of seed development by measurement and observation of ehanges in seed moisture content, weight, colour, endosperm consistency, germination capacity and yield in perennial ryegrass Grasslands Ruanui, timothy Grasslands Kahu and a New Zealand strain of prairie grass (Bromus unioloides). Seed moisture content was high (60–70%) after anthesis and declined at different rates, depending on the species and the weather. Maximum seed dry weight (maturity) was reached approximately 30 days after peak anthesis in all species and was influenced by N application and grazing. Colour changes in the seedhead and endosperm solidification proved unsatisfactory as measures of maturity. Endosperm solidification was reached 4, 11 and 12 days before maximum seed dry weight in ryegrass, timothy and prairie grass, respectively. Seeds removed from the plant as little as 7, 10 and 4 days after anthesis in ryegrass, timothy, and prairie grass, respectively, germinated, provided that dormancy was broken; but they did not retain viability after 3 months storage. Maximum viability of ryegrass, timothy and prairie grass seed tested immediately after harvest occurred 30, 38 and 16 days after anthesis, compared with 17, 35 and 12 days, respeetively, when germination testing was delayed for 3 months. In ryegrass, grazing caused a significant increase in seed yield in the second year while N application alone did not significantly increase yield. In timothy, grazing and to a lesser extent N, were both detrimental to seed yield in the second year. Highest yields were obtained in treatments not receiving either grazing or N. In prairie grass, grazing depressed and N application increased yields in both years. In all species similar or increased yield could be obtained by mowing the crop at, or slightly prior to, seed maturity and allowing seed development and ripening to continue on the cut straw for up to 10 days. Using this technique higher seed yields were obtained in ryegrass and timothy than when seed was direct-harvested. In prairie grass similar yields were obtained whether the erop was direct-harvested or threshed following drying in the swath for 10 days. The use of ‘drying curves’ for the prediction of correct cutting time of seed crops is suggested for ryegrass, timothy and prairie grass.     

Seed development and seed shedding in North Italian ecotypes of Lolium multiflorum

Seed development and seed shedding were studied in seven populations of Lolium multiflorum. Five of these populations were from the North Italian Plains, two from the Piedmont area and three from the Lombardy region. The remaining populations were Delecta, a variety derived from ecotypes from the Lombardy Plain, and RvP Lemtal. Seed shedding was greatest in the three ecotypes from the Lombardy Plain and lowest in RvP Lemtal. The two ecotypes from the Piedmont Plain, and Delecta, gave intermediate values. Moisture loss during ripening was greatest in the Lombardy ecotypes but there were no differences in the time taken to reach maximum 1000-seed weight. Germination values had reached a maximum 27 d after anthesis in all populations. It is suggested that the North Italian ecotypes, or varieties derived from them, should be harvested by direct combining at a moisture concentration of 450 g kg^-1 (≡45%) to obtain the maximum weight of germinable seed.     

Seed growth of three perennial ryegrass cultivars sown on two dates and treated with trinexapac ethyl straw shortener

First‐year crops of diploid perennial ryegrass (cvs. Meridian, Bronsyn and Grasslands Impact) were sown on 1 April and 14 May 2008. Applications of trinexapac ethyl (TE) plant growth regulator at 0, 200 and 400 g a.i. ha^?1 were used to shorten stems to examine the impact of seed growth. Seed filling followed a consistent sigmoidal growth pattern with a lag phase of 127°C days, and linear duration of 390°C days. Time to 95% of final seed weight was 517°C days. Seed yield increases from TE were from higher numbers of first‐grade seeds m^?2, achieved by a higher rate of seed filling during the linear phase of 0·115 mg per °C day per spike. For all cultivars, the maximum stem dry weight occurred at 310–400°C days post‐anthesis, which suggest the stem was a strong sink. As seeds developed, their demand for assimilate increased and they drew more from the stem. At harvest, stem weights from TE treatments were 25% heavier than at anthesis, while untreated ‘Bronsyn’ and ‘Grasslands Impact’ stems were similar to those at anthesis. Thus, stems treated with TE contributed assimilates to increase seed yield but were still a net sink with assimilates in the stem at harvest. Trinexapac ethyl rate induced an inverse relationship between seed yield and stem height. This showed that competition for assimilate between stems and growing seeds limited the seed yield. Management or genetic factors that reduce stem height are likely to increase seed yields of perennial ryegrass.     

The effects of density, date of inflorescence emergence, date of harvesting and temperature upon seed quality in tetraploid hybrid ryegrasses

Thousand-seed weight, germination and seedling dry weight were measured in some tetraploid hybrid ryegrasses to study variations in seed quality. In cv. Sabrina, seed from spaced plants had a higher 1000-seed weight and seedling dry weight, and a slower germination rate than seed from narrow drills. Seed from later emerging groups of inflorescences had a low 1000-seed weight and seedling dry weight, but a high germination rate. Seeds of cv. Sabrina, Leri and Augusta harvested at between 10 and 25 d after peak anthesis had low 1000-seed weights, low germination rates and low seedling dry weights. Air temperatures between inflorescence emergence and seed maturity also affected seed quality; an increase in temperature from a 15°/10°C regime to a constant 25°C environment reduced 1000-seed weight and seedling dry weight, but increased germination rate. It is concluded that year-to-year variation in seed characters will occur because of temperature and other climatic changes, but seed quality can also be influenced by the time at which the seed is harvested. If combine harvesting is carried out at a moisture concentration of about 400 g kg^-1 (≡40%) then maximum yields of seed of a high quality should be obtained.     

啤酒大麦种子在成熟过程中品质形成的研究

以 4个啤酒大麦品种 ,研究啤酒大麦种子在种子发育过程中啤酒大麦品质的形成 ,结果表明 :啤酒大麦种子的千粒重随种子的成熟呈直线上升的趋势 ,而蛋白质的含量在种子成熟过程中变化较小 ,呈波状变化 ;抽穗后 36d内随种子的发育成熟 ,发芽率呈上升的趋势 ,抽穗后 36d是大麦种子最佳收获时间 ,此时收获的大麦种子具较高的发芽势与发芽率相对应的 ,此时收获的大麦种子活力、POD和a -淀粉酶活性也最高     

VARIATIONS IN SEED QUALITY BETWEEN CERTIFIED SEED LOTS OF PERENNIAL RYEGRASS, AND THEIR RELATIONSHIP TO NITROGEN SUPPLY AND MOISTURE STATUS DURING SEED DEVELOPMENT

Ten Certified Seed lots of S23 perennial ryegrass produced in different counties in England during 1966, and ten lots produced in 1972, were examined for differences in characters affecting seed quality. The 1966 seed lots differed significantly in 1000–seed weight, germination rate, N content of the seed and seedling dry weight, and there was a significant correlation between seed N content and the seedling weight of the progeny. In both S23 and S24 perennial ryegrass N applied at inflorescence emergence or at anthesis increased N content of the seed and seedling dry weight. In S24 application of N at anthesis increased 1000–seed weight also. When plants of S23 perennial ryegrass were subjected to reduced moisture supplies their seed N content was increased. It is concluded that late N applications to grass seed crops may affect seed quality.     

Precipitation during anthesis reduces seed set in perennial ryegrass

In perennial ryegrass seed production, the establishment of seed yield potential occurs until the point of anthesis. However, utilizing potential seed yield is predominately focused on processes after anthesis, namely seed set (%) and seed filling. In practice, seed yield is the product of the number of harvested seeds remaining after cleaning and average seed weight. For this study, the anthesis patterns and seed set were recorded in a diploid variety grown in seed production fields in three different Danish regions with contrasting weather conditions and investigated in 2013 and 2014. Increases in the total precipitation during anthesis reduced the anthesis synchrony and the seed set, which ranged from 50% to 66%. Under semi‐controlled environmental conditions in which the influence of precipitation was excluded, the seed set was found to be influenced by the floret position in the spikelet and ranged from 73% in the florets in basal positions to 25% in the distal florets. It is suggested that a lower number of florets per spikelet will reduce the anthesis period. These results may provide insights for breeding programmes focused on increasing seed yield.     

The effect of light intensity after anthesis on dry matter distribution and seed yield of Lolium perenne L.

The effect of light intensity after onset of anthesis on dry matter distribution, water soluble carbohydrate (WSC) concentration and seed filling in Lolium perenne was investigated in a pot experiment. Spaced plants of five clones were brought to flowering and exposed to four light intensities (24%, 57%, 100%, 115% of natural light) from 7 days after onset of anthesis onwards. The two oldest flowering tillers (i.e. the main and the first tiller) were separated from the rest of the plant and dissected after a seed-filling period of 450°Cd (temperature sum counting from 7 days after onset of anthesis). Their stem dry weight and WSC concentration were reduced at the lowest light intensity. WSC amount was more reduced in the first, younger, tiller. Seed yield per ear of the main tiller was reduced by 14% because seed set and average seed weight were lower at the 24% light intensity. Seed yield and seed number per ear of the first tiller were lowered by 21% and 17%, respectively, at the 24% light intensity, but average seed weight was not. The relative contribution of the seeds to total tiller weight was about 20% and was similar for both tillers and all light intensities. WSC concentration and WSC amount in the stem + rachis were reduced only at 24% light in the main tiller and at 24% and 57% light in the first tiller. It is inferred that seed yield was not limited by assimilate availability, but by the ability of the seeds to utilize fully the abundantly available reserves in the stem. The tiller can support seed yield under a wide range of tight intensities.     

壮芽灵浸种对德香4103直播群体结构和产量的影响

大田直播条件下,研究了壮芽灵浸种对三系杂交水稻德香4103群体结构和产量的影响。结果表明：（1）壮芽灵浸种可以显著提高稻种的发芽势,但发芽率提高不显著;（2）壮芽灵浸种可以缩短从始苗到全苗的时间2 d,在播种量相同的条件下,基本苗和出苗率得到显著提高,基本苗从56.67万株/hm^2提高到68.89万株/hm^2,出苗率从75％提高到91％;（3）壮芽灵浸种可以显著提高群体最高苗数和成穗率,最高苗从573.33万/hm^2提高到612.22万/hm^2,成穗率从44％提高到47％;（4）壮芽灵浸种后有效穗数、结实率、千粒重显著提高,增产达7.70％。     

Seed development and seed yield potential of Italian ryegrass (Lolium multiflorum Lam.) populations

Greenhouse and field experiments were carried out to study the seed development and seed yield potential of three populations of Italian ryegrass (Lolium multiflorum Lam.). These included an ecotype (Bb 1276) collected in the Lombardy Plain region of northern Italy, cv. Tribune, which was derived from this ecotype, and cv. Lemtal, a widely used cultivar from Belgium. Artificial seed shedding techniques in the green-house study showed that Bb 1276 began shedding seed at a higher moisture content than cv. Tribune which in turn was higher than cv. Lemtal. The pattern and rate of shedding was similar for all three populations and generally Bb 1276 and cv. Tribune gave a greater proportion of shed seed than cv. Lemtal. Although the pattern of decline in seed moisture content was similar for all three populations, generally cv. Lemtal had a higher moisture content than cv. Tribune with Bb 1276 the lowest. Cultivar Lemtal had the highest mean 1000 seed weight, and Bb 1276 the lowest, with cv. Tribune intermediate. The field study involving cv. Tribune and cv. Lemtal showed that with the exception of 1000 seed weight, which for cv. Tribune was some 6% lower than that of cv. Lemtal, all the seed yield components were similar. Seed yields taken every 3 days after the standing crop had reached 50% moisture content showed that both cultivars increased in yield until harvest 3. After this date the seed yield of cv. Lemtal remained stable up to harvest 5 while that of cv. Tribune declined. The maximum seed yield of cv. Tribune was achieved at a seed moisture content of 42·9% while that of cv. Lemtal remained stable from 42·3% to 37·5%. The seed moisture content of the two cultivars again showed a similar pattern of decline but it was not possible to show consistent differences between cv. Lemtal and cv. Tribune. The 1000 seed weight of cv. Tribune was lower than that of cv. Lemtal, and the maximum seed weight of cv. Tribune appeared to be achieved earlier. Germination counts taken after harvest showed both populations exhibiting a high level of post harvest dormancy. Later counts taken 3 months after harvest were significantly higher than those taken earlier and there were no differences between cultivars or harvests. The results are discussed in relation to the potential for selecting for improved seed yield potential in Lolium multiflorum Lam. Populations from northern Italy and suggestions are made for maximizing the harvested seed yield of cv. Tribune.     

Optimum time of combine harvesting for amenity grasses grown for seed

The relationships between, and changes in moisture content, 1000-seed weight, germination percentage and seed yield were determined from anthesis onwards in ten amenity grasses in 1975. These relationships were used to indicate the optimum date for combine harvesting and to give some indication of the consequences which follow if harvest was not carried out at this stage. In all species seed moisture content declined, and 1000-seed weight and germination increased to a maximum value, during ripening.     

The effect of time of harvest on seed production of three red clover cultivars

Small plots of red clover cv. Sabtoron, S123 (diploids) and Hungaropoly (tetraploid) were harvested for seed production at two-week intervals from 19 August to 17 October inclusive in 1981, inflorescence appearance rate, bee density and components of yield having been monitored throughout the summer. Inflorescence appearance rate reached a maximum at the end of July/early August for Hungaropoly and Sabtoron and during mid-August for S123. Bee density followed a similar pattern. Florets and seeds per inflorescence and 1000-seed weight decreased as flowering progressed except during the first three weeks in July. Potential seed yield was calculated from the components of yield for the harvests taken on 3 and 18 September. Losses in seed yield (difference between actual and potential) up to and during harvesting, threshing and cleaning were lower in the tetraploid cultivar (27–39%) than the diploid cultivars (35–l55%). Each cultivar had an optimum harvest time before which yield was affected by immature seeds and beyond which it was adversely affected by shedding of inflorescences and seeds and sprouting of seeds on the inflorescences. The optimum time to harvest Sabtoron was early September, Hungaropoly early to mid-September and the late flowering cultivar S123 mid-September when less than 4% of the inflorescences were still unripe. Seed yield and inflorescences per unit area were lower in the tetraploid cv, Hungaropoly (maximum 542 kg ha⁻¹) than diploid cv. Sabtoron and S123 (864 and 897 kg ha⁻¹ respectively) although the tetraptoid had heavier seeds. It is concluded that the optimum time to harvest red clover for seed production is about three or four weeks after the end of the period of rapid inflorescence production and that this coincides with the time when only a small proportion of unripe inflorescences remain.     

不同成熟度京科968种子活力与种子物理化学特性的关系研究

以京科968为材料,2013年在甘肃分析授粉后35~62 d的不同成熟度种子的5个物理特性(长度、宽度、灰度、百粒重和容重)和8个生理生化特性(糖、蛋白、淀粉、油脂和MDA含量以及含水量、电导率和SOD酶活性)。结果表明,随着收获期的推迟,京科968品种5个物理特性和蛋白、淀粉、油脂、SOD酶活性逐渐增加,然后达到平台期;糖、MDA、含水量和电导率则随之下降。采用标准发芽率、人工老化发芽率、冷冻发芽率和冷浸发芽率分析不同成熟度种子的活力。结果表明,随收获期推迟种子活力不断提高,在授粉后59 d,4种评价方法的活力指标均处于最高点,该时期为该品种的最佳收获期。相关性分析发现,种子活力指标与种子物理特性和生理化学特性之间均存在显著相关性。     

芝麻蒴果及种子的生长发育特性

通过对芝麻品种中芝11蒴果及种子的生长发育过程中蒴果长度、体积及鲜干重和种子鲜干重、活力及种子中粗蛋白、粗脂肪和脂肪酸含量的测定，获得结果如下：（1）蒴果长度和体积在24～27d达到最大值，随后进入失水收缩阶段，30d左右基本定型。（2）籽粒干重在授粉后36d达到最大值，此时种子发芽率、发芽势和活力指数均为最高，即此时种子已经达到生理成熟。（3）侧位蒴果与中位蒴果的发育基本同步，但各项指标均弱于中位蒴果。（4）种子中粗蛋白质在种子发育15d以前便已达到一定水平，随后缓慢增加，粗脂肪在种子发育的18d之前增长迅速，18d以后积累较缓慢，第33d到达最大值，不同脂肪酸含量变化不同。     

Potential of winged bean pods and their products in Papua New Guinea

Three winged bean varieties (UPS 31, 121 and 122) were grown in randomised blocks in the UPNG Agriculture Garden under two levels of nitrogren fertilizer and harvested at weekly intervals until maturity. While whole pods reached their maximum length, width and limit of suitability as a green vegetable by 21 days after anthesis, the crude fat, protein and fibre contents continued to increase further on a fresh weight basis with the ratio of pod case to seed fat and protein decreasing on a dry weight basis. The reverse was true when fibre was considered. There was a very small effect from increased N fertilizer level on fat, protein and fibre contents. There was little difference in nutrient content between varieties except that UPS 31 contained more fibre. UPS 122 showed the greatest pod length, number of seeds per pod and seed weight, followed by UPS 121, then UPS 31; the same order was apparent when ripe seed fat and protein yields were considered. The potential of winged bean as a vegetable, grain legume and oilseed crop is discussed in terms of projected commercial outlay and nutritional advantages.     

不同成熟度京科968种子活力与种子物理化学特性的关系研究

以京科968为试验材料,分析授粉后35~62 d的不同成熟度种子的5个物理特性和8个生理生化特性。结果表明,随着收获期的推迟,5个物理特性和蛋白、淀粉、油脂、SOD酶活性逐渐增加,然后达到平台期;糖、MDA、含水量和电导率则随之下降。采用标准发芽率、人工老化发芽率、冷冻发芽率和冷浸发芽率分析不同成熟度种子的活力,结果表明,随收获期推迟,种子活力不断提高,在授粉后59 d时4种评价方法的活力指标均处于最高点,为该品种的最佳收获期。相关性分析发现,种子活力指标与种子物理特性和生理化学特性之间均存在显著相关性,这些指标也有可能用来指示不同成熟度种子的活力。     

Evaluation of seed vigor in soybean germplasms from different eco-regions

Seed vigor plays an essential role in soybean production. Soybean seed is sensitive to environment and easy to get seed deterioration. Generally soybean seed vigor can be maintained for less than one year and have to be multiplied every year. Varieties with good seed vigor are essential for maintaining planting population and stable yield. In this research, 419 germplasms from three eco-regions, South China, Huanghuai region and Northeast China, were evaluated for seed vigor by assessing germination ratio, germination potential and germination index. About 34.8% of tested germplasm had germination ratio equal or more than 85%, suggested by the national soybean seed quality standard of China. Only 9 from 82 tested cultivars met the seed standard. Seed germination ratio distribution had obvious regional feature. Landraces performed better seed vigor than cultivars. Germplasms from South China had stronger seed vigor compared to those from Huanghuai and Northeast regions. Seed vigor has no significant relationship with maturity and 100-seed weight. Totally 21 germplasms with strong seed vigor, favor maturation and seed size were identified and can be used in future breeding program.