首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Potato production in isohyperthermic temperature regimes (mean annual soil temperature higher than 22°C) has been considered impractical physiologically and economically. However, recent experiments with potatoes (var. Kennebec) on a clayey, kaolinitic, isohyperthermic Tropeptic Eutrustox of Hawaii during the winters of 1980 and 1981 and the summer of 1980, indicate that although seasonal variation in the tropics is minimal when compared to temperate regions, there is enough of a distinction in temperature that potato production is possible and favored during the cooler winter months. Soil temperatures, measured at 20-cm depth, in irrigated plots range from 18 to 20°C in winter and 24 to 26°C in summer. Tuber initiation in winter and summer began at 40 and 55 days after planting, respectively. Maturity was delayed by 20 days in summer. Yields in irrigated plots were 36,000 in winter and 25,000 kg/ha in summer; in nonirrigated plots, yields were 14,600 in winter and 7,900 kg/ha in summer. Nutrient uptake and water and energy use were less efficient in summer. The results indicated that winter is the most suitable season for potato production in the warm tropics.  相似文献   

2.
The DM production from INRA 200, an early maturing hybrid maize grown for silage, was 10±6 and 14 5 t/ha in mid-October 1972 and 1973 (4±2 and 5±8 tons/ac). The plant population in both years was approximately 112,000/ha (45,320/ac). Whole-crop and cob DM percentages were 18±2 and 21±3 for 1972 and 39±9 and 53±0 for 1973, respectively. The cob yields were 49 and 10±4 t/ha (2±0 and 4±1 tons/ac) in 1972 and 1973 and cob in the two years accounted for 46 and 72% of total yield. At harvest the 1973 crop was 4–6 weeks more mature than the 1972 crop. These differences were attributed to the difference in accumulated temperature recorded from May till October, which was 567°C days in 1972 and 817 in 1973. Whole-crop DM content, yield of cob and yield of cob as a percentage of total yield were studied against seasonal temperature accumulation. In the case of DM percentage there was a highly significant linear regression which showed that 627°C days were needed to mature maize to 24% DM content.  相似文献   

3.
Germination of annual pasture species was studied under controlled‐environment conditions in south‐western Australia at temperatures in the range from 4°C to 35°C. Subterranean clover (Trifolium subterraneum) and Wimmera ryegrass (Lolium rigidum) had a germination of 90% between 12°C and 29°C, whereas capeweed (Arctotheca calendula) had a high germination percentage in a much narrower temperature range with an optimum of 25°C. Growth of subterranean clover, capeweed and Wimmera ryegrass between 28 and 49 days after sowing (DAS) was also studied at two photon flux densities, 13 and 30 mol m?2 d?1, and at diel temperatures in the range from 15/10°C to 33/28°C. Pasture species grown at a density of 1000 plants m?2 accumulated at least twice the amount of shoot dry matter when subjected to temperatures of 21/16°C and 27/22°C, compared with a lower temperature of 15/10°C and a higher temperature of 33/28°C. Except at the highest temperature and at high photon flux density, capeweed had lower green area indices (GAI) than the other two species at 28 DAS. Crop growth rates between 28 and 49 DAS were higher in Wimmera ryegrass than in the other two species, whereas subterranean clover had a lower relative growth rate than the other two species at all temperatures and both photon flux densities. Subterranean clover and capeweed intercepted a greater proportion of the incident radiation compared with Wimmera ryegrass. The values of radiation interception and GAI were used to estimate the number of DAS to reach 75% radiation interception [f(0·75)]. The number of days to reach f(0·75) decreased with increasing temperature from 15/10°C to reach a minimum at 27/22°C. The time taken to achieve f(0·75) was always shorter by about 10 d when the photon flux density was 30 mol m?2 d?1 in the autumn compared with 13 mol m?2 d?1 in the winter. These results are discussed in relation to the early growth of annual pasture in the field.  相似文献   

4.
Summary In pot culture experiments over 2 consecutive years, 20 potato genotypes of varying heat tolerance were grown under long day conditions and heat stressed by being exposed to high (38 °C/21 °C mean day/night) temperature. The percent increase in mean internode length of heat stressed plants over those grown at normal temperatue (25°C/16°C day/night) was correlated with the percent tuber dry matter yield of the heat stressed plants (r=0.618, P=0.01). In the same 20 genotypes, grown under short day conditions at normal temperature, the fraction of leaf bud cuttings exposed to high night temperature (23°C) that produced tuber initials correlated with the percentage increase in internode elongation in stem cuttings exposed to 25°C compared with those exposed to 15°C (r=0.680. P=0.01). Thus the relative changes in internode elongation are related to thermal tolerance, and it is suggested that this can be used as a selection criterion for heat tolerance.  相似文献   

5.
Scenarios of global climate change forecast an increase in air temperature of 3°C over the next 100 years in eastern Canada. Growth and nutritive value of cool‐season grasses are known to be affected by air temperature. It is also believed that grasses grown at high latitude have a greater nutritive value. The objectives of this study were to assess the effect of four combinations of day/night temperature and photoperiod (15 h–17/5°C; 15 h–22/10°C; 15 h–28/15°C; and 17 h‐17/5°C) on dry‐matter (DM) yield, in vitro true DM digestibility (IVTD), in vitro digestibility of neutral‐detergent fibre (NDF), and concentrations of NDF, acid‐detergent fibre (ADF), lignin, minerals and non‐structural carbohydrates (NSC) in timothy grown under controlled conditions. Furthermore, herbage was harvested in the morning and in the afternoon to assess the impact of the time of harvest. The dietary cation–anion difference [DCAD = (K+ + Na+) ? (Cl? + 0·6 S2?)] and the grass tetany index [GT index = K+/(Ca2+ + Mg2+)] were also calculated. Higher temperature regimes significantly decreased IVTD and digestibility of NDF but had a limited effect on concentrations of NDF, ADF and lignin. DM yield of herbage was less and the concentration of NSC was greater in timothy grown under a temperature regime of 28/15°C than the 17/5°C and 22/10°C regimes; this effect is mainly explained by a response to temperature stress. Values of DCAD and the GT index of herbage were also lower under the 28/15°C than the 17/5°C and 22/10°C regimes as a result of a decreased plant K concentration. Under the 17/5°C regime, an increase in 2 h of photoperiod resulted in increased DM yield, decreased concentrations of K, Ca, Mg, Cl and N, and an increased starch concentration; IVTD or digestibility of NDF were not affected, although lignin concentration was reduced. Harvesting timothy in the afternoon rather than in the morning resulted in higher NSC, mainly sucrose, concentrations, and decreased ADF and NDF concentrations. The forecasted increase in air temperature in eastern Canada over the next 100 years will result in lower yields and nutritive value of timothy.  相似文献   

6.
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.  相似文献   

7.
The effect of forage removal on the growth of five winter and five spring triticale genotypes was studied in 1992 and 1993 in field experiments in north-eastern Spain. When cut, winter triticales produced more biomass and leaf area than spring types owing to their higher tillering capacity. The leaf area index (LAI) at anthesis was similar in both groups in both clipped and uncut plots, but spring triticales had a greater leaf area on the main stem than winter types. Winter types had a greater leaf area on the tillers than spring types. Spring and winter types had a similar physiological response to forage removal, except for modifications in flag leaf area. In spring types triticale flag leaf area was reduced by clipping, whereas in winter types flag leaf area was increased. Forage removal resulted in less dry-matter accumulation in all plant parts, maximum weight of the plant being reduced by about 20% and the rate of growth by around 13%. LAI at anthesis decreased by 37% as a result of clipping, and the leaf area duration from anthesis to maturity decreased by 36%. The duration of growth increased after clipping. Heading, anthesis and maturity dates were delayed by clipping, but grain filling duration was not affected.  相似文献   

8.
Summary

Atmospheric carbon dioxide (CO2) concentration has risen from about 270 mmol (CO2) mol?1 (air) (i.e., mole fraction of dry atmospheric air basis) before 1700 to about 370 mmol mol ?1 currently. General Circulation Models (GCM) have predicted a global temperature rise of 2.8 to 5.2°C for a doubling of CO2. This review examines evapotranspiration and water-use efficiency responses of plants to rising CO2 and climatic changes, especially temperature. Doubling of CO2 will decrease leaf stomatal conductance to water vapor about 40%. However, water use by C3 crop plants under field conditions has usually been decreased only 12% or less for two reasons. Firstly, feedbacks in the energy balance of plant foliage cause leaf temperatures to rise as stomatal conductance is decreased. Increases of leaf temperature raise the vapor pressure of water inside the leaf, which increases the leaf-to-air vapor pressure difference. This increased driving force for transpiration offsets in large part the decreased leaf conductance caused by elevated CO2. Secondly, CO2 enrichment tends to cause leaf area to increase more rapidly in many crops. This increased leaf surface area for transpiration also offsets part of the decreased stomatal conductance per unit leaf area on the whole canopy evapotranspiration, but the energy budget feedbacks are more important.

Experiments point to a yield enhancement of 30 to 35% for C3 crops for the direct effects a doubling of CO2 (without ancillary climate change). If temperature rises, this yield enhancement may be greater for vegetative growth but less for seed grain yield. Experiments on both ambient and elevated CO2 treatments in sunlit growth chambers showed that transpiration rates increased 20% when air temperature was changed from 28 to 33 °C and increased 30% when temperature was increased from 28 to 35 °C. Thus, under well-watered conditions, evapotranspiration will increase about 4 to 5% per 1°C rise in temperature.

Crop model predictions of yields of soybean and maize showed a reduction due to temperature increases by two GCM models. Under Southeastern USA conditions, doubling CO2 in the Goddard Institute for Space Studies (GISS) climate change scenario resulted in an 12% increase in yields, but yields decreased 50% in the Geophysical Fluids Dynamics Laboratory (GFDL) climate change scenario. Optimum irrigation for both models gave yield increases of about 10%. These model results illustrate the critical requirement of water for production of crops. Under rainfed conditions, crop yields could suffer tremendously if growing season precipitation is decreased, but yields could increase moderately if growing season precipitation is increased. Under the high growing season rainfall scenario (GISS), irrigation requirements for optimum soil water were increased 22%, but under the low rainfall scenario (GFDL), irrigation requirements were increased 111%.

Without the effects of climate change, rising CO2 will cause an increase in crop water-use efficiency (WUE). Most of the increases in WUE will be due to increases in dry matter, with little or no contribution from decreases in water use per unit land area. Growers could produce higher yields per unit land area with higher total production, or maintain the same total production with less land and less total water use. However, if temperatures rise, transpirational water use will increase, and WUE will decline. Higher temperatures, and especially less rainfall, would raise the irrigation requirements of crops. Competition for water resources from other uses could result in less water available for irrigation.  相似文献   

9.
A study was conducted to establish a growth rate response of potato plant (Solanum tuberosum L.) tops to exposure to 72-hr periods of six constant temperature treatments (10, 15, 20, 25, 30, 35°C) and to determine a thermal optimum for vegetative potato growth rates. The plants were maintained under “no stress” soil moisture conditions throughout the study. The temperature treatments were accomplished by inserting the plants into a growth chamber for 72 hours at selected temperatures. Maximum growth (as measured by percent change in leaf area) occurred at 25°C with temperature growth differences significant at the 5% level. Plant height measurements (percent change occurring during treatment time) showed maximum stem elongation at 30°C during an early growth stage and 25°C during stage 2 (4 weeks later). Predictive models developed from the data indicate maximum rates of leaf area increase in both growth stages occur at 24.7°C and that maximum rates of stem elongation occur at 31.3 and 27.4°C for growth stages 1 and 2, respectively. Leaf water potential and stomatal resistance measurements taken at the end of each treatment period indicated that no water stress occurred.  相似文献   

10.
Chinese yam (‘yam’) was grown at different carbon dioxide concentrations ([CO2]), namely, ambient and elevated (ambient + 200 μmol mol?1), under low- and high-temperature regimes in summer and autumn, separately. For comparison, rice was also grown under these conditions. Mean air temperatures in the low- and high-temperatures were respectively 24.1 and 29.1 °C in summer experiment and 20.2 and 24.9 °C in autumn experiment. In summer experiment, yam vine length, leaf area, leaf dry weight (DW), and total DW were significantly higher under elevated [CO2] than ambient [CO2] in both temperature regimes. Additionally, number of leaves, vine DW, and root DW were significantly higher under elevated [CO2] than under ambient [CO2] in the low-temperature regime. In autumn experiment, tuber DW was significantly higher under elevated [CO2] than under ambient [CO2] in the high-temperature regime. These results demonstrate that yam shows positive growth responses to elevated [CO2]. Analysis of variance revealed that significant effect of [CO2] × air temperature interaction on yam total DW was not detected. Elevated-to-ambient [CO2] ratios of all growth parameters in summer experiment were higher in yam than in rice. The results suggest that the contribution of elevated [CO2] is higher in yam than in rice under summer. Yam net photosynthetic rate was significantly higher under elevated [CO2] than under ambient [CO2] in both temperature regimes in summer. Elevated [CO2] significantly affected on the rate in yam but not in rice in both experiments. These findings indicate that photosynthesis responds more readily to elevated [CO2] in yam than in rice.  相似文献   

11.
The relationship of photosynthesis and dark respiration to reduced potato growth at temperatures above 20°C was determined. Ten potato clones were propagated in vitro from sterile plandets and grown in a growth chamber at 20/15°C and 30/25°C (day/night) with an 18 hr. daylength. Plants were harvested 26 to 30 days after transplanting. Daylength was decreased to 12 hrs. to induce tuberization and plants were harvested at 45-51 and 75-79 days after transplanting. At each harvest one plant from each cultivar was chosen from each of five blocks and selected growth (tuber number and dry weight of leaves, stems, roots and stolons, and tubers) and physiological variates [leaf area, net photosynthesis, maintenance dark respiration, and chlorophyll fluorescence parameters 0 (Initial), P (Peak), T (Terminal), P-O (Variable fluorescence) and P-T (Fluorescence quenching)] were measured. The high temperature decreased root and stolon, tuber and total dry weight and increased stem dry weight. Amongst physiological variates, the higher temperature decreased leaf area, net photosynthesis and maintenance dark respiration. The chlorophyll fluorescence parameter 0 significantly increased, which also increased the P and T parameters. Variable fluorescence (P-O) and fluorescence quenching (PT) were not significantly affected by the growth temperature. The analyses of covariance, in which physiological variates were used as covariates to remove significant differences in growth variates, indicated that the most effective covariate was the T chlorophyll fluorescence parameter. The least effective covariates were leaf dark respiration and the chlorophyll fluorescence parameters P-O and P-T. The changes in 0 fluorescence suggest that reduced photosynthetic efficiency, particularly in Photosystem II, plays a major role in reduced potato production at high temperatures.  相似文献   

12.
  相似文献   

13.
Municipal solid waste (MSW) compost is readily available in eastern Canada and may be a good source of fertility. A 3-year experiment evaluated the effects of MSW compost and fertilizer on soil fertility, elemental composition and yield of potato (Solanum tuberosum L.) grown in a sandy loam soil. Three rates of compost (MSW1, MSW2, and MSW3), one rate of fertilizer (NPK), and one mixture of 1/2 MSW1 compost and 1/2 NPK fertilizer were applied annually to plots in a three-crop rotation; each year the MSW1 rate attempted to match the rate of P applied in the NPK treatment. Mehlich-3 extracts were evaluated for 11 elements at two soil depths (0?C15 and 15?C30 cm). Potato shoots and roots or whole plants were assessed for 16 elements. Treatments had no consistent significant influence on marketable tuber yields although the NPK treatment produced mathematically the highest yields. After 3 years, treatments had influenced soil concentrations of K, Ca, S, Cu, Zn, and Na in Mehlich-3 extracts at the 0?C15 cm depth, but only the concentration of Na at the 15?C30 cm depth. The concentration of Mg in the plant tissue was consistently highest in plants fertilized with NPK; this treatment also produced higher Mn concentrations in the last 2 years. Shoot Cu concentrations were highest in the MSW3 plots. The compost did not increase heavy metal concentrations in shoot, root or whole-plant tissue and would be safe to use at agronomic rates of application.  相似文献   

14.
Timothy (Phleum pratense L.) is an important forage grass used for pasture, hay and silage in regions with cool and humid growth seasons. Harvesting conditions could reduce its nutritive value, particularly with extended wilting periods. To understand how daytime or night‐time wilting influences the nutritive value of timothy, this study investigated the metabolism of non‐structural carbohydrates, including fructan and starch, together with total soluble protein and amino acid patterns in timothy plants harvested at two maturity stages (heading and anthesis) and wilted under controlled conditions for 24 h at two temperatures (15°C, 20°C) and two light regimes (darkness, light) by simulating different wilting management practices. Correlation analysis with the whole dataset showed that soluble protein, glucose and starch contents declined in plant tissues concomitantly with water loss, while amino acid, sucrose and fructose contents increased. Transient increase in amino acid content suggests that the decrease in protein content was due to proteolysis during wilting. Sucrose and fructose contents generally increased in plant tissues harvested at anthesis and wilted in light whereas they were unaffected in plants wilted in darkness. Fructan content remained stable. Fructan exohydrolase (FEH) and soluble acid invertase (INV) activities were well preserved during the first 12 h of wilting and might facilitate the fermentation process at the beginning of ensiling by supplying fructose from fructans and hexoses from sucrose to the fermentive bacteria.  相似文献   

15.
《Field Crops Research》1988,19(3):153-166
The potato has only recently been introduced into isohyperthermic environments, and is grown during the dry season. There is a need to determine the optimum planting time and the range of possible planting dates. Two contrasting cultivars, ‘Cosima’ and DTO-2, were studied to determine the influence of planting date on their growth and development. They were planted on five dates from early to late dry season (October-January) during two years, at 14° N lat. in The Philippines. Another objective, studied during the second year, was to compare seed produced under hot lowland conditions and stored for 8 months, with newly sprouted seed grown under cool highland temperatures.Potato plants grew faster and tuberized earlier for later planting dates. Physiologically young seed of Cosima and DTO-2 always produced plants with superior canopies. Tuber bulking was linear up to about 70 days after planting. Total dry-matter production was highest with young Cosima seed, exceeding 100 g plant−1 for all planting dates except the last. Old Cosima and DTO-2 seed generally produced between 80 and 100 g dry matter plant−1. Final tuber yields were highest with the mid dry-season planting (December) during both years with highland seed Cosima yielding 30 t ha−1. Lowland seed of Cosima yielded over 21 t ha−1 for the first 4 planting dates, significantly less than yields from highland seed. Yield differences increased with later planting. Although highland seed is recommended, lowland seed is an alternative for poor farmers. The final tuber yield of Cosima decreased by 12% with a minimum air temperature rise from 18.5 to 21° C, while DTO-2 was more adversely affected. Based on these results, minimum ait temperatures above 21 °C are unsuitable for potato production. Total intercepted solar radiation was positively correlated with final tuber yields and total dry-matter production. Efficiency of conversion into dry matter was about 70% of that in cool temperate climates.  相似文献   

16.
Night minimum temperatures of 9°C and a regime with periods of one month at 16°C,and 5°C, followed by 13°C, were compared with a night regime of 13°C for their effects on Botrytis cinerea Pers. in an early-season glasshouse tomato crop. Day temperatures were the same in all treatments. Nine independent compartments were used in a randomized block design in which sub-plots were treated with or without a programme of fungicidal sprays of iprodione started at one of three stages in relation to the first infection by B. cinerea. The low-temperature regime of 9°C significantly increased numbers of lesions caused by B. cinerea on stems and leaves during April and May, but not in subsequent months. Increases during May and June of fallen fruits from 9°C plants were not statistically significant. Stem and leaf infections were not increased by the 16/5/13°C energy-saving regime, although losses due to fallen fruit were greater during May. Treatment with iprodione sprays caused significant decreases in disease in all night temperature regimes and was similar in effect to an increase in night temperature from 9°C to 13°C. Responses to the timing of the first application of iprodione were never significant and differed during the first month of disease assessment only. Yields were significantly lower in the first month of cropping at 9°C but there were no differences in yield between the 13°C and the 16/5/13°C regimes.  相似文献   

17.
《Field Crops Research》1995,41(1):13-23
The objectives of this study were to evaluate effects of ambient and double ambient [CO2] at a range of growing temperatures on photosynthesis, respiration, transpiration, water-use efficiency and dry matter accumulation of cotton plants (Gossypium hirsutum L., cv. DPL 50). In Experiment I, plants were grown outdoors until first bloom, then transferred into naturally lit growth chambers and grown for 22 days at 30/18°C with five CO2 concentrations varying from 350 to 900 μl l−1. In Experiment II, air temperatures were maintained at 20/12, 25/17, 30/22, and 35/27°C day/night during a 70-day experimental period with [CO2] of 350 and 700 μl l−1 at each temperature. Photosynthesis increased with [CO2] from 350 to 700 μl l−1 and with temperature. Plants grown at 35/27°C produced fewer bolls due to abscission compared with plants grown at optimum temperatures (30/20°C). At higher [CO2], water-use efficiency increased at all temperatures due mainly to increased canopy photosynthesis but also to more limited extent to reduced canopy transpiration. Increased photosynthesis at higher [CO2] resulted in greater dry matter accumulation at all temperatures except at 20/12°C. Respiration increased as dry matter and temperature increased. Plants grown at higher [CO2] had less respiration per unit dry matter but more per unit area. These results indicate that future increases in [CO2] are likely to benefit cotton production by increasing carbon assimilation under temperatures favorable for cotton growth. Reduced fruit weights at higher temperatures indicate potential negative effects on production if air temperatures increase as projected in a high-CO2 world.  相似文献   

18.
An apparatus in which shoot and root CO2 exchange and acetylene reduction can be simultaneously measured in specific white cloverrhizobium associations is described. In mature stolonating clover there was a fairly constant ratio between net photosynthesis, root respiration and acetylene reduction. Of the net carbon fixed daily (12 h light of 80 W m-2, 400–700 nm; day/night temperature 15°C) 12% was lost during the dark period by the shoot and 17% by the nodulated root. Changes in the rate of acetylene reduction by nodulated root systems occurred more slowly than those in rates of root respiration in response to reduced irradiance. In 21·5 h continuous darkness the rate of acetylene reduction remained constant. Responses to increased irradiance were more immediate in both root respiration and acetylene reduction. In plants maintained at 15°C in a 12-h, 80-W m-2 photoperiod there was no significant diurnal variation in acetylene reduction or root respiration. Acetylene depressed root respiration by 20%. Assuming the energy requirement of the nitrogenase system to be the same when reducing acetylene and N the depression can be used as an indication of the energy requirement of fixed N assimilation, metabolism and export in the nodulated root. Of the net carbon fixed daily 3·4% was utilized in this way in plants growing in a 12-h photoperiod (80 W m-2, 400–700 nm) at 15°C.  相似文献   

19.
Non-leaf green organs of wheat plants may have significant photosynthetic potential and contribute to grain yield when the plants are subjected to stress at late growth stages. Canopy structure, change of green non-leaf organ area (e.g., ear, peduncle, sheath), the proportion of green non-leaf organs area to total green area and the contribution proportion from different organs’ photosynthate to grain yield in winter wheat (Triticum aestivum L.) were studied at Wuqiao Experiment Station of China Agricultural University, Hebei, China, in 2001-2002 and 2002-2003 using two winter wheat cultivars, Shijiazhuang8 (SJZ-8) and Lumai21 (LM-21). Four irrigation treatments used were W0 (no water applied during spring), W1 (750 m3 ha−1 water applied at elongation), W2 (1500 m3 ha−1 applied 50% at elongation and 50% at anthesis) and W4 (3000 m3 ha−1 applied 25% at upstanding, booting, anthesis and grain filling), respectively. Results showed that the area of top three leaf blades decreased and the proportion of green non-leaf organ area to the total green area at anthesis increased with the decreasing of water supply. Root weight increased in the 0-100 cm soil layer and decreased in the 100-200 cm layer when water supply increased, suggesting reducing irrigation enhanced root weight in deep soil layer. The photosynthetic contribution of non-leaf organs above flag leaf node to grain yield increased with decreasing water supply, and was significantly higher than that of the flag leaf blade contribution. Winter wheat grain yield increased, but water use efficiency (WUE) decreased, with increase in water supply. Higher light transmission ratio in the canopy after anthesis was achieved with smaller size and high quality top leaf blades, higher grain-leaf ratio and larger proportion of green non-leaf area, which lead to higher canopy photosynthetic rate and WUE after anthesis. Irrigation of 1500 m3 ha−1 applied in two parts, 750 m3 ha−1 applied at elongation and another 750 m3 ha−1 applied at anthesis, was the best irrigation scheme for efficient water use and for high yield in winter wheat.  相似文献   

20.
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.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号