Seed yield,oil content and fatty acid composition of Oenothera biennis L. affected by harvest date and harvest method

Evening primrose (Oenothera biennis L.) has become a subject of agricultural interest because of the potential market for γ-linolenic acid, which is useful in medicine and nutrition. O. biennis has good potential for agricultural production, but due to its indeterminate growth it can not be harvested at once as seed are formed and ripened heterogeneously. As a result there is high seed wastage due to shattering. Field experiments were carried out to verify the influence of the harvest time (early, middle and late) and harvest method (conventional harvest method, defoliation by herbicide and defoliation by flame) on the seed yield, seed yield components, oil content, fatty acid composition and protein content of the O. biennis L. cv. “Anothera”. From the results of the three harvest times in the autumn-sown experiment, a significant influence on seed yield was observed in the late harvest. Of all the three harvest times in the spring experiments, not showed any significant influence on seed yield. However, the harvest method did produce a significant influence on seed yield in the first spring experiment. Different harvest times did not have significant influence on oil content except the second spring trial. The harvest method led to significant differences on the oil content when the plants were sown in autumn. In the second spring experiment seed protein content was significantly influenced by harvest time. In all experiments, the content of γ-linolenic acid (GLA) was influenced by harvest time. Based on obtained results, it can be concluded that 75–80 and 100 days after flowering could be recommended as harvest times for spring and autumn-sown O. biennis L. cv. “Anothera” in Germany, respectively. Desiccation as a harvest technique in some cases tended to influence on seed yield, PDM, SDM, oil content, stearic acid, oleic acid and linoleic acid. Defoliation by herbicide was more effective than those of flame in our experiments.     

Sowing date, harvest date and the yield of forage brassica crops

The effect of sowing date, within the period from late May to mid-August, on the DM yield of five leafy forage brassica crops sown to a stand was examined over the period 1976–78. Kale was the crop most sensitive to variation in sowing date and yields declined progressively with later sowings. There was no yield benefit from sowing rapes or stubble turnips earlier than mid- to late-June. Raphanobrassica produced yields as good as rape when sown in June. In 1978, DM yields of rape, kale and Raphanobrassica increased from September to early November, largely as a result of stem growth; kale was slower to accumulate DM than rape in late summer but continued growing longer into the autumn. The DM concentrations of all crops increased from September to December. Rape had a higher DM concentration than stubble turnip. Raphanobrassica was 10–25 g kg^-1 lower in DM concentration than rape or kale. Raphanobrassica produced 23–59% flowering plants from late-May to early-June sowing. Harvest date affected DM yield and concentration, leaf: stem ratio and flowering percentage. The effects of sowing dale on DM concentration were small.     

Bumper harvest of super rice in south and north China

Recently. a great progress was made in breeding and cultivation of super rice in China. The South Demonstration Acceptance Meeting of China Super Rice was held in Oct 17. 2000 in Xinchang County, Zhejiang Province. Yield monitoring group organized by the Department of Science,Technology and Education, Ministry of Agriculture, China, was consisting of famous rice research scientists, agricultural technology extension experts, and government officials. In the demonstration meeting, the group investigated the rice growth of the demonstration field of the improved integrated cultivation technology of super hybrid rice, Xieyou 9308. Four representative demonstration fields from 6.87 ha of the demonstration were harvested after the current investigation of the group.     

Effect of harvest date on the chemical composition and nutritive value of Cerastium holosteoides

Abstract Cerastium holosteoides is a short‐lived plant often found in small proportions on dry and mesotropic semi‐natural, species‐rich grassland communities. To obtain more information about its nutritive value, two experiments on Arrhenatheretum elatioris grassland were carried out to examine the effect of harvest date on in vitro organic matter digestibility (IVOMD), neutral‐detergent fibre (NDF), acid‐detergent fibre (ADF), acid‐detergent lignin (ADL), estimated net energy for lactation (NEL) and crude protein (CP) concentrations of C. holosteoides, and selection of this plant by dairy cows grazing on semi‐natural grassland. C. holosteoides starts flowering in spring and continuously develops new flowers on new branches throughout the summer. Harvests were made in relation to particular growth stages of Dactylis glomerata present in the sward: (A) tillering; (B) stem elongation; (C) ear emergence; (D) flowering; and (E) ripening. Chemical composition and nutritive value were evaluated in 1998 and 1999. With advancing maturity, IVOMD of C. holosteoides decreased from 0·771 at growth stage A to 0·485 at growth stage E. At the same time, CP concentration decreased from 153 to 69 g kg^?1 dry matter (DM) and estimated NEL concentration from 6·00 to 4·07 MJ kg^?1 DM. With advancing maturity, there was a significant increase in NDF, ADF and ADL concentrations. In the summer harvest season, C. holosteoides contained significantly higher NDF, ADF and ADL concentrations, lower NEL concentration and had a lower IVOMD value than in the spring. Differences between years were also found for IVOMD and for NDF, ADF, ADL and NEL concentrations. In a grazing experiment in the year 1999, at growth stage B, Simmental cows grazed an A. elatioris sward in which the main species was D. glomerata (0·092), and the proportion of C. holosteoides was 0·034. C. holosteoides was, on average, grazed by cows to the same relative extent as other species in the sward.     

Causes of variation in the rate of increase of wheat harvest index

Several crop simulation models calculate grain yield by assuming that the rate of change of harvest index (δHI/δt) is constant (at rate k) during grain growth. Such behaviour has been identified in many crops, although the literature contains many examples of variations in k. The concept is useful if it approximates the truth in most circumstances, or if departures from both linearity and constancy are predictable from either the environment or the state of the crop. In this paper we examine the hypothesis that much of the variation in k is related to both crop biomass at the start of grain filling (BGF) and the crop growth rate during grain growth (CGF). Calculations using simple partitioning rules indicated that both factors are important. We showed that k increases rapidly as BGF decreases below about 9.0 Mg DM/ha, but decreases only slowly with increases of BGF above 9.0 Mg DM/ha. The analysis also showed that the increase in HI with time is quadratic rather than linear. We analysed data from 68 field grown wheat crops with variation in cultivar, location, irrigation, ambient CO₂ concentration and sowing dates. These showed an almost three-fold variation in k (0.0058–0.0164 day⁻¹). Across all data sets, there was a negative linear relationship (y = 0.02 − 0.0006x, R² = 0.41, p < 0.001) between k and BGF. Overall, these results suggest that some of the variation in k can be accounted for by differences in BGF. We suggest that any model that uses harvest index change as a basis for calculating yield should account, at least, for variations in BGF.     

Influence of post harvest temperature treatments,storage period and harvest date on development of spraing caused by tobacco rattle virus and potato mop-top virus

Summary The frequency of PMTV-spraing and TRV-spraing increased during storage in several cultivars. The only exception was cv. Saturna, where a decrease was observed in 1992. A spraing inducing treatment of one week at 18 °C followed by one week at 8 °C immediately after an early harvest increased the frequency and provided a rough estimate of the development of spraing in untreated tubers during storage. Under most circumstances wound healing at 25 °C compared with 15 °C resulted in a lower frequency of spraing during the storage period. The date of harvest had an important influence on development of spraing during storage and on the effect of post harvest temperature treatments. Therefore, physiological processes that induce or erase spraing are strongly related to tuber maturity. The mechanisms controlling development of symptoms seemingly are identical for the two spraing inducing vira.     

蓖麻杂交组合收获指数评价

为了提高蓖麻杂交育种效率，研究杂交组合收获指数与性状之间的关系，观察和测量了133个蓖麻杂交组合的13个农艺性状，即收获指数、单株产量、生物量、百粒重、有效穗数、一级分枝数、株高、茎粗、主茎节数、主穗长、主穗位高、叶绿素含量、净光合速率。采用相关分析和回归分析研究133个杂交组合的农艺性状间的关系。结果表明，不同蓖麻杂交组合的收获指数差异较大，变幅为0.126~0.644，平均值为0.398；133个杂交组合中收获指数在0.5以上的组合仅占16.54%。相关关系结果表明，收获指数与单株产量呈极显著正相关，与主穗长呈极显著负相关。回归分析表明，单株产量、株高、主穗长、有效穗数4个性状对收获指数的影响较大。因此在育种过程中，选择主穗花序较长、植株相对较高、一级分枝数较多的个体，可提高育成材料的单株产量。     

Effect of soil temperatures at harvest on the bruise resistance of potatoes

The effect of soil temperature at harvest time on the bruise resistance of potatoes was determined by dropping a weight onto tubers, by dropping tubers, and by sampling commercially harvested potatoes. The results show that a positive linear relationship exists with bruise resistance increasing as soil temperature increases. Shifts in the regression function during the one season studied suggest that some factor or factors which were influenced by time also affected the bruise resistance rating. However temperature of the tubers (and hence, of the soil) at harvest remains the major determinant of the resistance of potato tubers to bruising. Correlation between the bruise rating and soil temperature, as found in the commercial operation, indicates that the relationship is of a magnitude to be of economic importance. An average of 20% of the Katahdin tubers sampled were bruised in the harvesting process and were a potential loss from marketing channels.     

The effect of harvest date and tuber-borne sclerotia on the severity ofRhizoctonia disease of potato

Experiments performed in 1976 and 1977 examined the effect of harvest date on the development of tuber-borne sclerotia and the effect of these sclerotia onRhizoctonia disease severity of potato. Results from tubers harvested at seven weekly intervals in 1975 indicate maximum sclerotial development occurred 3–4 weeks after vine killing. When these tubers were planted the following year, few differences occurred in disease severity of stems and stolons with respect to prior harvest date. However, the tubers which had remained in the ground 4–7 weeks after vine killing in 1975 produced the largest and greatest number of sclerotia on progeny tubers harvested in 1976. Experiments in 1976 and 1977 demonstrated that tubers with approximately 20% sclerotial coverage produced stems and stolons with significantly more severeRhizoctonia disease compared to tubers with no visible sclerotia. Sclerotial coverage on tubers of less than 20% did not significantly increase disease severity.     

Nitrogen fertilizatioin of potatoes for early summer harvest

Rates of N applied to sandy loam soil with wheat as the preceding years crop was studied as to the influence on tuber yields of potatoes grown for early summer harvest in Southwestern Indiana. Most of the yield response was to the first 75 lbs/acre (84 kg/ha) increment of N which increased the yield of US #1 potatoes 61 cwt/acre in 1967 and 52 cwt/acre in 1968. The total solids were not significantly decreased by the first increment of N applied which was also the N range of rapid yield increase. N fertilization increased the N content of the foliage from 3.0 to 4.0% in 1967 and 3.97 to 5.17 in 1968 and the tubers from 1.36 to 2.96 in 1968. The first 75 lbs N increment was efficiently converted to crude protein, 48% incorporation, but the succeeding increments were poorly converted.     

蔗行间种黄豆花生,获得蔗豆双丰收

简述蔗行间种黄豆、花生增产增收的效果.分析了蔗行间种黄豆花生增产原因,以及其配套栽培技术.     

春小麦穗发芽抗性鉴定及机理研究

对国内外57个春小麦品种（系）开花后不同时期进行穗发芽抗性和α-淀粉酶活性的测定，用改进的凝胶扩散法测定小麦种子α-淀粉酶活性。结果表明，不同春小麦品种的抗穗发育特性及α-淀粉酶活性具有明显差别，来自东北地区的大部分主栽品种的穗发芽抗性中等。总体上，红粒品种的穗发芽抗性比普通白粒品种强，在白粒品种中也存在抗性极强的品种。不同穗型对发芽率的结果影响不大，小麦品种的穗发芽抗性可以用开花后35－40d的籽粒发芽率为指标，不同品种的α-淀粉酶活性物降落值存在显著差异，穗发芽率与种子中α-淀粉酶活性呈显著正相关，与降落值呈显著负相关，开花25－40d期间，穗发芽总体上呈上升趋势,α-淀粉酶有下降趋势，并趋于稳定。     

Effect of variety and harvest date on tuber sugars and chip color

The major tuber sugars—glucose, fructose and sucrose — in tubers of the Red Pontiac, Kennebec and Monona potato varieties harvested five times during the 1970 growing season were determined quantitatively by a gas-liquid Chromatographic technique. Also, chips were made from tubers and chip color was measured objectively and reported as Rd values. Red Pontiac tubers produced the darkest-colored chips (Rd-15.5), and its tubers tended to accumulate the highest levels of the three sugars. The major difference between Monona, which produced chips with the lightest color (Rd-21.1), and Kennebec (Rd-19.5) was the very low level of glucose found in the tubers of Monona. Varieties produced chips lightest in color at the second (8/31) or third (9/15) harvest dates. Conversely, darkest-colored chips were obtained from each variety at the fourth harvest date (9/28). This was attributed to the cool, wet weather. Sugar content also varied during the harvesting schedule. Glucose content changed little until late in the season when an increase occurred. Fructose tended to decline until the final harvest when a distinct increase was obtained. Sucrose declined significantly through the third harvest, but changed little thereafter.     

Field harvest damage affects potato tuber respiration and sugar content

Field and laboratory experiments demonstrate that damage to potato tubers increased tuber respiration, which declined with time. Measurement of tuber respiration with an infra-red gas analyzer can be a sensitive indicator of amount of tuber damage in actual field harvests. Damage of tubers had no effect on total sugar content but decreased sucrose content when measured ten days after harvest.     

早稻穗发芽对水稻产量和米质的影响

以田间自然条件下穗发芽的早稻品种为材料,研究了穗发芽对水稻产量和稻米品质的影响。结果表明：穗发芽严重影响水稻的千粒重,千粒重降低6．91％～24．45％,同时,穗发芽导致槌米率、精米率和整精米率下降10％～90％,并使透明度和胶稠度下降,严重影响了稻米的加工品质和蒸煮品质。     

油后移栽棉的生育特点及配套高产栽培技术

通过5年的试验示范研究，分析了油后移栽棉的优势和生育特点，总结了存在的问题，提出了相应的配套高产栽培技术。