Relationship between leaf gas exchange characteristics and productivity of potato clones grown at different temperatures

The rate of dark respiration (Rd) and net photosynthesis (Pn) at various leaf temperatures was examined in three potato clones (Solatium tuberosum L.) differing in heat tolerance. Plants were grown at low (25/12 C, day/night) and high (35/25 C) greenhouse air temperatures for five weeks, beginning two weeks after tuberization. Gas exchange characteristics were measured by manometric and infrared gas analyzer techniques. Respiration:photosynthesis ratios were calculated as indicators of leaf carbon balance. High greenhouse temperature reduced whole plant and tuber growth rate of all clones, however, the reduction was highest in the cultivar Russet Burbank (heat sensitive). Gas exchange characteristics did not explain differences in heat tolerance. The heat tolerant cultivar Desiree had Rd similar to Russet Burbank, while the clone DTO-28, also heat tolerant, had lower Rd of mature leaves than Russet Burbank or Desiree. However, all clones had similar Rd of immature leaves. There was no apparent relationship between heat tolerance and Pn for the three clones. DTO-28 had lower respirationrphotosynthesis ratios of immature and mature leaves than Russet Burbank 4 weeks after the start of the high temperature treatment. Desiree had respiration:photosynthesis ratios as high as Russet Burbank. At different sampling times, Rd increased in a linear and curvilinear manner with increasing leaf temperature up to 40 C. Heat tolerant and sensitive clones had similar rates of increase in Rd with increasing leaf temperature. Simultaneous measurement of Rd and Pn did not help explain differences in heat tolerance among clones. However, determination of respirationrphotosynthesis ratios may help explain the physiological basis for heat tolerance of some clones.     

Influence of heat stress on dry matter production and photo-assimilate partitioning by four potato clones

Partitioning patterns of¹⁴C labeled assimilates were studied to determine their relationship to dry matter accumulation and distribution in four potato clones (Desiree, DTO-28, LT-1 and Russet Burbank). Plants placed in growth chambers at 35/25 C day/night temperature and 12-hour photo-period two weeks after tuber initiation were compared with plants grown continuously at 25/12 C. Two weeks after temperature treatments were begun, the most recently expanded leaf was labeled with¹⁴CO₂ for 30 minutes, and plants were harvested 20 hours or 15 days later. High temperature reduced total dry matter production and altered dry matter distribution in favor of vines at the expense of tubers. Partitioning of¹⁴C assimilates generally followed the pattern of dry matter distribution. Potato clones exhibited variation in¹⁴C assimilate export from labeled leaves and in partitioning to vines and tubers. Assimilate partitioning to tubers was not consistently higher in clones considered heat tolerant.     

Dry matter accumulation in potato clones under seasonal high temperature conditions in Pakistan

The effects of seasonal high temperatures on potatoes were investigated under field conditions near Peshawar, Pakistan. Five potato clones (A79196-1, Desiree, DTO-28, LT-1, Russet Burbank) were grown during the spring season at two locations. Canopy development, vine dry weight and tuber dry weight were determined at 13-day intervals, starting 68 days after planting (DAP). Tuber yield was higher in heat tolerant clones compared to heat susceptible clones. Location significantly affected tuber dry weights. Tuber dry weights of Russet Burbank were consistently lower than those of DTO-28. Ground canopy cover of DTO-28 occurred earlier and reached maximum at 75 DAP, compared to 90 DAP for Desiree. DTO-28, because of its high tuber yield under cool as well as hot temperatures, and its relatively early bulking, should be a promising clone for a short duration crop in hotter regions.     

Potato Stem Density Effects on Canopy Development and Production

Controlled environment studies with potato frequently assume responses from single-stem potato plants can be extrapolated to the field where multiple-stemmed plants are common. Controlled environment studies were conducted to characterize differences in canopy growth, development, and dry matter production between single- and multiple-stemmed potted potatoes. Leaf area distribution was influenced by stem density, with main stem and apical lateral branch leaf area being 150% to 200% larger in triple-stemmed (3S) versus single-stemmed (1S) pots (P < 0.01), while basal lateral branch leaf area was 50% less (P < 0.01). Basal lateral branches were more developed in 1S pots with longer branch lengths, more leaf area, and higher orders of branching. In a second experiment, more leaves were initiated in higher-density pots; however, individual leaf areas were approximately 50% smaller than those in 1S pots. Total leaf area and total, vegetative, and tuber dry matter production were unaffected by stem density in either experiment on a per pot basis. Development and growth of lower basal lateral branches in the 1S potato canopy offset any initial advantage in leaf numbers in the multiple-stemmed plants. These results appeared to validate the assumption that, given a late maturing cultivar and adequate nutrition, responses from single-stemmed plants can be extended to multiple-stemmed plants when expressed on a production area basis. These findings have practical considerations for potato researchers who conduct growth chamber experiments and potato modelers.     

Assessment of heat tolerance in potato (Solanum tuberosum ssp.tuberosum) under controlled environmental conditions: the ‘cutting technique’

Summary The ‘cutting technique’ or ‘tuberisation stimulus’ (TS) technique was investigated as a method of identifying heat tolerant clones ofSolanum tuberosum ssp.tuberosum. TS levels were assessed, using leaf cuttings, for 100 experimental clones growing under heat stress in a controlled environment (35/15°C day/night temperatures, 16 h photoperiod). No correlation was found with the tuber yields of these clones when grown in an irrigated trial in Israel. The relationship between TS levels and tuber production was investigated using early and later maturing cultivars grown with and without heat stress. These experiments showed that the cv. Blanka had high TS levels in all environments and high tuber fresh weights when grown under heat stress. However, the correlation between TS levels and tuber fresh weight for all cultivars was weak (r=0.45). The results indicated that this TS technique is unlikely to be an accurate method of screeningtuberosum clones for heat tolerance.     

Effects of Drought and Shading on Non-structural Carbohydrate Stored in the Stem of Potato (Solanum tuberosum L.)

Abstract

Most studies on non-structural carbohydrate (NSC) are concentrated on the leaf and tuber, and little is known about NSC in the stem and its function. To test the hypothesis that NSC stored in stem contributes to stable tuber bulking under stress conditions, we grew plants in pots in a greenhouse under drought and shading conditions for 17 d during tuber bulking. Compared with the control, drought and shading significantly reduced leaf and stem dry weights (DW) and total NSC concentration in the main stem base. However, tuber DW increased by 77% in drought and by 46% in shading conditions relative to the control. The contributions of NSC loss in the stem to tuber DW increase in drought and shading conditions were 37% and 54%, respectively. This study suggests that NSC stored in the stem base is supplied to tuber under stress conditions to support tuber bulking.     

玉米杂交种苗期耐热性评价

以24个适宜黄淮海地区种植的玉米杂交种为试验材料,采用水培试验,人工模拟高温条件,测定玉米株高、茎粗、叶面积、根条数、胚根长、地上部干物质量、根系干物质量、总干物质量、根冠比和叶绿素相对含量等10个性状,以各性状的耐热系数作为参数,运用主成分分析、聚类分析和逐步回归等对其耐热性进行综合评价。结果表明,总干物质量、根冠比、茎粗、叶面积、叶绿素相对含量和胚根长这6个性状可作为玉米杂交种苗期耐热性鉴定指标。根据综合耐热能力的大小,把24个玉米杂交种划分为高度耐热型、中度耐热型、弱耐热型和热敏感型4类。     

马铃薯器官生长发育与产量形成的研究

马铃薯叶面积、叶干重以及块茎干物重和块茎体积的变化动态均符合三次曲线变化 ,地上茎干重、茎粗、株高符合S型曲线变化 ,其中 ,叶干重的峰值早于叶面积的峰值 ,块茎体积的增长则在出苗后 5 5～ 70d内最快。马铃薯地上茎的生长主要是伸长与充实 ,但伸长较充实缓慢、持续时间更长。匍匐茎与块茎的形成是马铃薯产量形成的前提条件 ,二者的建成与植株其它器官的生长发育密切相关 :匍匐茎和块茎的形成与叶片和地上茎形成时期并进 ,所以 ,马铃薯块茎的建成与地上营养器官的生长发育存在着光合产物的竞争 ,但地上部器官的建成依然是产量形成的物质基础。     

Influence of the growth retardant B 995 on growth and yield of potatoes

Summary Stem elongation in a potato crop can be reduced by spraying the growth retardant B 995 on the foliage. This treatment generally did not change the total dry matter production. Only in the last period of growth did B 995-treated plots show a higher total dry weight than the untreated ones. This was caused by a slightly later senescence of the treated plots. The B 995 treatment caused a marked change in the dry matter distribution: stem weight was decreased and tuber weight increased, but leaf weight was generally not influenced. With plants showing considerable vegetative growth, these effects resulted in an increased tuber yield. High nitrogen plots treated with B 995 combined a long productive periode with a favourable dry matter distribution, producing a very high tuber yield at the end of the growing period.     

马铃薯主要生理性状和产量性状相关性的研究

以大西洋、滇薯6号、PB04和PB08 4个加工型马铃薯品种(系)为供试材料,进行不同品种块茎形成期主要生理性状和收获时产量特性的比较及部分性状间的相关性研究。结果表明:在马铃薯的块茎形成期大西洋的光合速率最强,根系活力较强,抗逆性较强,其农艺性状和块茎产量特征均表现较好。相关分析结果显示,马铃薯的块茎数量、块茎产量、干物质含量和块茎淀粉含量与光合速率呈正相关,生物产量、块茎数量、块茎产量、干物质含量和块茎淀粉含量与叶片电导率呈负相关,而生物产量与根系活力呈正相关。     

Internodal elongation: A potential screening technique for heat tolerance in potato

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.     

Application of calcium and nitrogen for mitigating heat stress effects on potatoes

This study was designed to investigate the effect of calcium and nitrogen application during heat stress on leaf calcium concentration, transpiration rate, membrane thermostability, and biomass accumulation and partitioning. Micropropagated Russet Burbank potato (Solanum tuberosum L). plants were transplanted into 20 L pots containing 1:1 (v/v) soil: perlite and exposed to 30/20C (D/N) temperatures for four weeks (weeks 9–12 after transplanting) in a controlled-environment growth room. The maximum temperature was maintained for 6 hr during the middle of the 14 hr photoperiod. The nutrition treatments were N before stress (NBS), N during stress (NDS) and Ca and N during stress (Ca+NDS). Calcium was supplied as Ca(NO₃)₂. All treatments received the same total amount of nitrogen. Native soil Ca level without amendment (550 mg Ca/kg soil) was sufficient for potato plant growth under normal temperatures. Plants given Ca and N during heat stress had the highest leaf Ca concentration and transpiration rate during and 2 weeks after conclusion of the heat stress period. When measured after 4 weeks of heat stress, area and fresh and dry weight of the most recently mature leaf was significantly greater in NDS and Ca+NDS plants compared to NBS plants. Cellular membrane thermostability (measured as ion leakage from heat-treated leaf disks) was not affected by any treatment prior to heat stress. However, leaf tissue from Ca+NDS plants exhibited significantly higher membrane thermostability compared to NBS plants after 2 and 4 weeks of heat stress. At harvest, NDS and Ca+NDS plants had significantly higher leaf/stem (fresh weight ratio) values compared to NBS plants. Also, Ca+NDS plants had significantly greater total tuber and biomass values than NBS and NDS plants. Results of this study suggest that some detrimental effects of heat stress on plant growth and stomatal function may be alleviated by Ca and N application during heat stress. The data also suggest that mitigation of heat stress by Ca and N application during heat stress may maintain plant productivity when optimum growing temperatures are restored.     

马铃薯块茎中干物质与蛋白质、维生素C及还原糖的关系

本试验对40份材料块茎中的干物质、粗蛋白、维生素C以及还原糖进行了分析,其中包括普通栽培种(Solanum tuberosum)20份,新型栽培种(Neo-tuberosum)5份,普通栽培种×新型栽培种杂种5份,二倍体栽培种(S.Phureja)9份,二倍体杂种(Neo-tuberosum双单倍体×S.phureja)1份。结果表明,干物质(％)、干物质中粗蛋白(％)、鲜薯中粗蛋白(％)、V_c(mg/100g鲜薯,以及还原糖含量(％)的平均数和标准差分别为19.8893±2.2448,11.9805±2.0367,2.3640±0.3881,8.5288±2.04322和0.6113±0.3031;干物质和干物质中的粗蛋白含量呈极显著负相关(r=-0.4118~(**)),但和鲜薯中粗蛋白含量呈不显著正相关(r=0.2083);干物质和V_c含量呈极显著正相关(r=0.4246~(**)),和还原糖含量呈不显著负相关(r=-0.2769)。     

Comparison of the growth of potato crops grown in autumn and spring in North Africa

Summary The relationships between intercepted solar radiation and dry matter production (total and tubers) were established for four cultivars of different maturity classes and using seed tubers of two physiological ages. The crops were grown in an autumn and a spring season in Tunisia. Radiation use efficiencies were lower in autumn than in spring and the quantity of intercepted radiation at tuber initiation was more than two times greater in autumn than in spring due to retarded tuberization in the autumn caused by the relatively high temperatures. In addition, tuber dry matter, number of stems per plant, tubers per stem and harvest indices were all lower in the autumn than in the spring season which explained why tuber yields in the spring season were higher than in the autumn.     

Reduction in potato growth at high temperature: role of photosynthesis and dark respiration

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.     

Validation of a simple potato growth model in the North Central United States

A simple potato growth model was validated in 1985 and 1986 at two dryland sites, Grand Forks, ND and Rosemount, MN, and one irrigated site, Hancock, WI. At each site, Russet Burbank potatoes were grown to maximize yield. Leaf area index and leaf, stem, root, and tuber biomass data were collected from replicated experiments every two weeks. Soil matric potentials, minimum and maximum temperatures, and solar radiation also were measured. Among sites, crop development rates and solar radiation receipts were similar, but final tuber yields differed by as much as 35 Mg/ha. Model predictions of leaf, stem, and tuber dry weights were similar to observed data both in terms of maximum values attained and seasonal development except for the experiment in Grand Forks in 1986 where the model over-estimated final tuber yield by 23 Mg/ha (115%). Soil aeration or salinity, factors not currently modeled, may account for this discrepancy. Modeled yield responses to defoliation were compared with field data from one of the experimental locations. At levels of defoliation below fifty percent, proportional yield reductions were similar between observed and modeled crops.     

Performance of potato minitubers in a controlled environment after different storage periods

Summary Minitubers of cultivars Agria and Liseta were harvested from the same plantlets on three dates. After each harvest, tubers were dried (1 day), cured (13 days) and cold stored at 2 °C in darkness and 80 % RH. Their performance was studied 65, 128, 191, 254, 317, 380, 443, 506 and 569 days after harvest. Minitubers (1–2 g) were planted in pots and grown for 8 weeks in a controlled environment. After 191 days of storage their growth was still extremely poor. In both cultivars, tallest plants and largest leaf areas per plant were observed in plants from tubers from the second and third harvests that had been stored for 317 days. Highest stem numbers, yields (total dry matter, tuber fresh weight) and harvest indices were achieved with 443 days storage with cv. Agria and 569 days storage with cv. Liseta. Tubers from the first harvest behaved slightly differently.     

马铃薯看叶施肥技术的初步研究

摘要对不同叶龄的施肥效果表明,浙江马铃薯追肥宜早不宜迟.以6～7叶顶叶展平为标志施肥对地上茎叶生长的促进作用显著,现蕾后地下块茎生长比其它叶龄追肥为优,干物质分配合理.追肥迟不仅产量降低,而且小薯比例增加.因此,6～7叶龄期为最适追肥期.该结论在生产上已初步得到验证.     

Effects of temperature and photoperiod on early growth and final number of tubers in potato (Solanum tuberosum L.)

Summary A phytotron experiment with all combinations of two photoperiod (12 or 18 h) and four temperature (18/12, 22/16, 26/20 or 30/24 °C; 12h/12h) treatments was carried out to analyse quantitative effects on early tuber growth, dry-matter partitioning and number of tubers of two cultivars. Higher temperatures and longer photoperiod delayed the onset of expolinear tuber growth and the onset of linear tuber bulking. Higher temperatures also gave lower absolute tuber growth rates. Photoperiod did not affect absolute tuber growth rate at lower temperatures. Higher temperature and longer photoperiod gave lower relative rates of partitioning of dry matter to the tubers. Differences between treatments in numbers of tubers initiated were inconsistent. This quantitative analysis of the effects of temperature and photoperiod on characteristics of tuber growth should prove useful in potato modelling.     

马铃薯高淀粉生理基础的研究——块茎淀粉含量与单株若干性状

本试验以高淀粉品种晋薯2号、中淀粉品种内薯3号和低淀粉品种紫花白为试验材料,设置了小区试验.在生育期间,从植株茎叶淀粉含量、单株叶面积、单株干物重、单株茎数和块茎数等方面与块茎淀粉含量的相关关系进行了研究,其结果:(1)叶片和茎秆中的淀粉含量与块茎淀粉含量呈正相关.因此,生育前中期叶片和生育中后期茎秆的淀粉含量,可做为马铃薯高淀粉育种早期选择的生理指标和品质预测的依据;(2)单株叶面积和单株干物重始终与块茎淀粉含量呈正相关.因此,单株最大叶面积和任何生育时期的单株干物重,均可做为马铃薯高淀粉育种早期选择和品质预测的生理指标;(3)单株茎数、单株块茎数与块茎淀粉含量呈正相关或显著正相关.故单株茎数、单株块茎数可做为马铃薯高淀粉育种早期选择的重要生理指标和品质预测的依据.