Analysis of differences in growth of cucumber genotypes under low light conditions in relation to night temperature

Summary Growth of four breeding lines and two cultivars of slicing cucumber with different growth at low temperature and light intensity was analysed in relation to night temperature. Plants were grown from 17 days after sowing at 20°C day temperature and 20, 15 or 10°C night temperature (NT), a light intensity of 24 W/m² visible radiation and a daylength of 8 hours. Data from six successive harvests, ending 47 days after sowing, were analysed according to a MANOVA procedure.RGR, NAR, LAR, SLA and LWR generally decreased with time. Ln W and RGR were largely similar at 20 and 15°C NT, but reduced at 10°C NT. LAR and SLA decreased at each lower NT, whereas LWR increased. NAR was only marginally affected by NT. Significant genotypic differences occurred for 1n W, LAR, SLA, LWR, stem length and percentage of dry matter in leaves and stems at all NT's and for RGR and NAR only at 20°C. Genotypic differences for 1n W could not be explained by differences for RGR, but by differences for initial plant weight.Significant genotype × night temperature interactions were present for LWR. Breeding lines increased LWR in response to lower NT, while that of cultivars remained fairly constant. Implications for breeding are discussed.Abbreviations and definitions L plant length - LA leaf area - W dry weight of the shoot - RGR relative growth rate (the increase in W per unit of time and unit of W) - NAR net assimilation rate (the increase in W per unit of time and unit of LA) - LAR leaf area ratio (the leaf area at time t per unit of W) - SLA specific leaf area (the leaf area at time t per unit of leaf weight) - LWR leaf weight ratio (the leaf weight at time t per unit of W) - RGR NAR × LAR - LAR SLA × LWR - MANOVA multivariate analysis of variance     

Inheritance of growth characters of tomato (Lycopersicon esculentum Mill.) under low energy conditions

Summary To study the mode of inheritance of W, RGR, NAR, LAR, SLA and LWR, the growth of 15 tomato genotypes and 104 of their F1's was analyzed. The plants were grown at a 19°C day temperature and a 10°C night temperature under a light intensity of 24 Wm^-2 visible radiation and a daylength of 8 hours. Combining ability analyses of variance revealed highly significant differences in GCA values between parents for all characters studied and significant SCA values for some of the characters. GCA values for NAR and LAR, and for NAR and SLA were strongly negatively correlated. A strong positive correlation existed between GCA values for LAR and SLA. The possibilities for improving growth under low energy conditions by using growth characters in breeding are discussed.Abbreviations W dry weight of the plant - RGR relative growth rate - NAR net assimilation rate - LAR leaf area ratio - SLA specific leaf area - LWR leaf weight ratio - MANOVA multivariate analysis of variance - GCA general combining ability - SCA specific combining ability     

Growth analyses of tomato genotypes grown under low night temperatures and low light intensity

Summary In three experiments the growth of 16 genotypes of tomato was examined. The plants were raised in growth rooms at a day temperature of 19°C and night temperatures of 14, 10 or 6°C respectively under a light intensity of 24 Wm^-2 visible radiation and a daylength of 8 hours. The results were analysed by a multivariate analysis of variance.Relative growth rate (RGR), leaf area ratio (LAR), specific leaf area (SLA) and leaf weight ratio (LWR) decreased with time. The change in net assimilation rate (NAR) was small. The decrease in RGR was mainly due to the decrease in LAR.RGR, LAR and SLA were lower and LWR slightly higher at lower night temperatures. NAR was hardly affected. The lower RGR at lower night temperatures was mainly due to a lower SLA.Significant differences between genotypes were found in total dry weight, NAR, LAR, SLA and LWR, but hardly in RGR. Significant genotype × temperature interactions occurred.LAR and SLA were positively, NAR and LAR, and NAR and SLA negatively correlated.     

Growth and development of maize (Zea mays L.) seedlings under chilling conditions in the field

Maize inbred lines of different origins were grown in spring (for 2 years at early and usual sowing dates) in northeastern Switzerland (latitude 47°27′ N; 550 and 720 m a.s.l.) until five to six leaves were fully developed. Averaged over all observation periods, the group of inbred lines used in hybrids for cool temperate regions (CT lines) showed better heterotrophic and autotrophic shoot growth and faster development than the group of lines adapted to warm tropical regions (CS lines). The more efficient autotrophic shoot growth of CT lines was expressed by higher rates of relative growth (RGR) and relative leaf area expansion (RLGR) and was related to a higher net assimilation rate (NAR) and a lower leaf area ratio (LAR). CT lines had better radiation use efficiency (RUE), higher rates of net photosynthesis (P_N), and lower specific leaf area (SLA) than CS lines. The greater RGR and RLGR of CT line Z 7 as compared to the CS line Penjalinan were related to a higher assimilation rate but not to a better use of carbohydrates; in Z 7 the balance between assimilation production and use resulted in a greater accumulation of soluble carbohydrates and starch. Genotypic variability existed for most growth parameters and was greatest for NAR. Growth responses of inbred lines under field conditions in spring were influenced mainly by temperature. Of all parameters, NAR was correlated best with temperature. Under decreasing temperature, RGR, RLGR, the rate of leaf appearances (RLA) and NAR decreased, whereas LAR, leaf area partitioning (LAP), and SLA increased slightly. The soluble carbohydrate content of Z 7 and Penjalinan also increased. RUE showed the best correlation with the daily minimum air temperature. Within the temperature limits of this experiment, no significant interactions were found between inbred line and temperature.     

低温胁迫下籽用西瓜幼苗生理变化与耐冷性的研究

以三叶一心期的籽用西瓜幼苗为材料,采用10℃低温胁迫的方法,研究了黑籽瓜兰州大片(wb10)和红籽瓜巢湖红(wb7)随着处理天数的延长幼苗的耐冷性、光合特性、生理特性的变化规律,以探讨籽用西瓜耐低温的生理机制,从而为籽用西瓜的引种栽培和抗寒品种选育提供理论依据。结果表明:不同品种籽用西瓜幼苗的叶绿素含量、Pn、Tr、Gs、Ci随低温胁迫时间的延长而逐渐降低;Pro、MDA、相对电导率随低温胁迫时间的延长而升高。两品种的冷害指数存在一定差异,耐冷性表现为wb10>wb7。低温胁迫下,耐冷性较强的wb10幼苗叶片中的叶绿素含量、Pn、Tr、Gs、Ci均高于耐冷性较弱的wb7,而耐冷性较强的wb10幼苗叶片中MDA含量、脯氨酸含量、相对电导率均低于wb7。综合试验中各项指标认为,耐冷性与品种的来源、类型及在低温下植株的冷害指数、光合特性和细胞膜稳定性有关。     

Differences between spring wheat cultivars in early growth

Summary Twelve spring wheat cultivars were grown as isolated plants in the field and their pre-anthesis growth was interpreted in terms of plant growth analysis. Relative growth rate (RGR) decreased steadily with time due to a decline of leaf area per unit plant weight (LAR), which could be explained by the reduction of the portion of leaf weight in total plant weight (LWR). Growth per unit leaf area (NAR) and leaf area per unit leaf weight (SLA) changed only little with time.Differences between cultivars for NAR and LAR were of similar magnitude: both 8% when measured by the genetic coefficient of variation. Because both quantities were negatively correlated, the genetic variation of RGR was only 5%. Genetic variation for LWR and SLA were also of similar size, both about 4%. Estimates of genetic variances and covariances based on cultivar means appeared to be biased strongly when the error variation of the means was neglected.Special attention is paid to the methodology of plant growth analysis.     

Primary Growth Parameters of Three Alfalfa Cultivars Adapted to Highland Climatic Conditions

An irrigated field study was conducted to determine the relative importance and inter‐relationships of growth parameters of three dormant alfalfa (Medicago sativa L.) cultivars grown in the highlands of Eastern Anatolia, Turkey, in 2000–2003. The fast‐growing cultivar Savas had the greatest dry matter (DM) yield at the final sampling date with the greatest mean crop growth rate. In addition to a greater relative growth rate (RGR), this cultivar had more stem branching and greater leaf area in the canopy, which resulted in greater leaf area index (LAI) and greater leaf area duration. Despite the considerable increase in leaf area ratio (LAR: leaf area per unit shoot DM), the reduction in RGR of all cultivars over time was the result of a large decline in net assimilation rate (NAR) due to increasing specific leaf area (SLA). Intracultivar variation in the RGR of alfalfa is mainly determined by NAR and SLA, and both were significantly higher for Savas than the other two cultivars. The relative importance of NAR and SLA to RGR changed due to increasing self‐shading as the LAI of the canopy increased, creating a trade‐off between NAR and SLA.     

Surface Structure of Leaves in Heat Tolerant Plants

The objective of our studies was to investigate the effect of high temperature on cabbage cultivars which were different in heat tolerance in terms of head formation.
We determined whether there were cultivar differences in the properties of epicuticular wax, growth parameters such as leaf number, leaf area and dry weight and whether these factors contribute to head formation under stress.
Four cabbage varieties including the Japanese heat tolerant cultivar Sousyu, were grown in pots at different temperatures in growth chambers.
The stability of the wax differed with the varieties. The wax of Kinsyun melted at a temperature of 32 °C during the day and 29 °C during the night, while the wax of the other varieties was more stable. The density of the tubes, plates or fibrils could be observed by light reflection. For Kinsyun as the low density caused a low reflection, the leaf colour was green, while for Sousyu the leaf colour was blue/white for Akiou, green/ blue and for Braunschweiger, blue.
We conclude that the function of cuticular wax in limiting cuticular transpiration is a product of the architecture of the deposits and the quantity of wax per unit area of leaf surface. Neither the wax structure nor the amount of eight varieties could be correlated with heat tolerance in terms of head formation.     

晚籼稻抽穗期冷害生态适应性评价

选择生育期相近的迟熟高产杂交稻组合或水稻品种（品系）,在自然条件下分期播种,寻找水稻抽穗期冷害相关的形态评价指标,并对参试材料进行抽穗期耐冷生态适应性评价。抽穗期遭受低温冷害胁迫后,主要农艺性状中受冷害程度大小顺序依次是每穗实粒数、单蔸产量、结实率、每穗总粒数、株高、穗长、千粒重;单蔸产量相对受害率（ＲＤＰ）与每穗实粒数ＲＤＰ、结实率ＲＤＰ、剑叶叶色分、抽穗期延尺天数分成极显著正相关。在低温冷害胁迫条件下,水稻不同基因型的抽穗期耐冷能力存在明显的差异。将判别水稻抽穗期耐冷能力的形态指标－－每穗实粒数ＲＤＰ、结实率ＲＤＰ、剑叶叶色、抽穗期延迟天数、苞穗率增加值进行量化,综合判别参试材料抽穗期对低温冷害的生态适应性。研究结果表明：籼穗交材料９５ＬＲ１０２后期耐冷能力强;带有部分粳稻血缘、正在生产中大面积种植的杂交稻     

Phenological development of East African highland banana involves trade-offs between physiological age and chronological age

The phenology of East African highland banana (Musa acuminata AAA-EA, hereafter referred to as ‘highland banana’) is poorly understood. We tested three hypotheses: (1) the physiological age at flowering is independent of site effects, (2) there is no difference in threshold size at flowering between sites with different growth potential, and (3) morphological and physiological components of highland banana relative growth rate (RGR) contribute equally to mitigate growth reduction in response to limiting supply of water, K or N. The physiological age of highland banana plants from field trials at Kawanda (central Uganda) and Ntungamo (south-western Uganda) was computed from daily temperature records. Growth analysis was conducted using RGR, net assimilation rate (NAR), specific leaf area (SLA) and leaf mass ratio (LMR) estimated from allometry. Growth response coefficients were used for quantifying the relative contribution of NAR, SLA and LMR to RGR. Physiological age at flowering was delayed by 739 °C d at Kawanda compared with that at Ntungamo whose chronological age at flowering was in turn 51 d older. At both sites a threshold total dry mass of 1.5 kg per plant was required for flowering. Faster absolute growth rate and NAR fostered by wet conditions, K input and cooler temperatures enabled plants at Ntungamo to attain the threshold total dry mass sooner than those at Kawanda, hence the phenotypic plasticity in age at flowering. Net assimilation rate contributed at least 90% to RGR increase due to wet conditions at both sites. The contribution of NAR to RGR increase in response to K at Kawanda reduced to 38% while that for SLA increased to 49%. Net assimilation rate contributes more to highland banana RGR modulation than SLA except when warmer conditions reduce NAR. Differences in crop growth rate cause phenotypic plasticity in highland banana rate of phenological development.     

Evaluation of chilling sensitivity in different rice varieties. Relationship between screening procedures applied during germination and vegetative growth

Summary Rice varieties were screened for chilling tolerance during germination and vegetative growth using different techniques. The effects of temperature during germination were investigated from 10 to 25°C. The screening was most effective at 10°C. Time of data collection has to be considered in order to discriminate slow germinating from chilling sensitive varieties. Chilling survival tests (10°C) applied at the 2-leaf stage revealed that different chilling durations brought complementary results: the longer treatments allowed to identify the most tolerant varieties, while shorter treatments allowed to distinguish intermediate from most sensitive rices. Results of chilling tests applied at the 2- and the 8-leaf stages showed a high correlation. Low-temperature electrolyte leakage and low-temperature fluorescence were also highly correlated to each other and to survival tests applied at the same development stage. By contrast, weak correlations were observed between low-temperature germination and plantlet chilling survival. It is concluded that low-temperature electrolyte leakage and low-temperature fluorescence are good indicators of chilling tolerance during the vegetative growth. The possibility to use a chilling screening procedure applied at this stage in order to predict the chilling tolerance at other development stages is discussed.     

两个超级杂交水稻品种物质生产的特性

定量分析超级杂交水稻若干群体指标的动态特征,以期为其高产栽培提供依据。于2011年和2012年在大田条件下,以超级杂交水稻准两优527、Q优6号和对照品种II优838为试材,通过连续测定干物质和叶面积,建立了水稻群体干物质和相对叶面积指数动态模型,进而以群体干物质和相对叶面积指数模型为基础,分析了超级杂交水稻作物生长率、相对生长率、光合势、净同化率、叶面积比率动态变化特征。结果表明,超级杂交水稻快增期的干物质积累量及其占总生物量的比例均高于对照。作物生长率(CGR)随移栽后时间呈先升高后下降的单峰曲线变化,其快增期的CGR较大。与对照相比,超级杂交水稻相对生长率(RGR)表现出上升快、峰值大、下降快的特点。准两优527在移栽后23 d至成熟期高于对照,Q优6号的RGR在移栽后43 d以前低于对照,移栽后43 d至113 d高于对照,两者在移栽后113 d至成熟期的RGR相差不大。不同水稻净同化率(NAR)随移栽后时间呈先上升后下降的单峰曲线变化,最大NAR出现在移栽后43~53 d。总光合势与快增期光合势及与快增期绿叶面积持续时间均呈极显著正相关。2个超级杂交水稻叶面积比率(LAR)在移栽后23 d至43 d迅速下降,移栽后43 d至73 d缓慢下降,移栽后73 d至成熟期快速下降,其快增期的LAR较大。     

Growth Analysis of Onion (Allium cepa L.) in Relation to Irrigation and Nitrogen Fertilization

Studies were carried out at the Indian Institute of Horticultural Research, Bangalore during winter seasons of 1982—83 and 1983—84 to analyse the growth rhythm of onion in relation to irrigation and N fertilization. It was observed that irrigation at 0.45 to 0.65 bar soil water potential recorded higher dry matter accumulation and distribution, leaf area index (LAI), leaf area duration (LAD), leaf area ratio (LAR) and crop growth rate (CGR) during most of the stages, while net assimilation rate (NAR) and relative growth rate (RGR) were not markedly affected. Highest harvest index was noticed with irrigation at 0.65 bar.
Nitrogen fertilization significantly increased dry matter accumulation and distribution into different parts, LAI, LAD, LAR, CGR and harvest index. Although NAR and RGR showed an increasing trend with N fertilization, the effect was not significant during most of the stages. There was no significant interaction between soil water potential and N fertilization on any of the growth parameters.     

玉米新品种‘裕丰303’的商业育种问题讨论

在大田生产中,‘先玉335’等美系新品种在耐密植、抗倒伏、抗南方锈病、抗大斑病、抗高温热害等方面的能力都较弱。为了通过育种手段解决以上问题,本研究以玉米新品种‘裕丰303’为试验材料,通过对其在国家（黄淮海夏播、东华北中晚熟、西北春播）以及各省区域试验和生产试验中的产量、抗旱性、耐高温热害、耐密性、籽粒品质等品种特性进行分析。结果表明‘裕丰303’不仅具备美系新品种的优良特征特性,还具有耐旱、耐高温热害、抗倒伏、抗南方锈病等性状优势,实现并大幅度超越笔者原定的育种目标。以此为基础,讨论了今后种质扩增、改良、创新的技术路线和避免遗传脆弱性风险出现等相关商业育种问题。强调在育种实践中应高度重视耐高温热害性状和耐旱性状的选育,特别要注重通过不断提升基因型与环境互作的正向超正常表达选育具有广泛适应性的新品种。     

Methods for evaluation of soybean chilling tolerance at the reproductive stage under artificial climatic conditions

Several evaluation methods for soybean chilling tolerance at the reproductive stage were examined under artificial climatic conditions. Comparisons were made on plants in control and treated plots using three cultivars differing in the level of chilling tolerance. In all methods, plants were grown at 22/17°C (day/night) until first flowering, and then transferred to growth chambers at 24/17°C for control and 15/15°C for chilling treatment, respectively. A method, in which plants were grown at 20/16°C after 4 weeks of the different temperature treatments, proved comparable to the conventional one, in which chilling tolerance at the flowering stage is evaluated using natural and artificial conditions. Another method, in which the plants in chilling treatment plots were grown at 15°C until maturity, also proved usable to evaluate genotypic differences in chilling tolerance independently of maturity time.     

宁夏设施番茄主栽品种芽期和苗期抗寒性评价

以9个不同番茄品种在低温下的发芽特性及苗期的冷害指数,综合评估其耐冷性,以期为生产上筛选抗寒性强的品种提供依据。试验结果,表明“嘉粉8346”和“爱吉168”均表现为耐低温较强的品种。     

人工合成小麦幼苗耐低温特性鉴定

为了鉴定不同小麦品种的耐低温特性,筛选耐低温种质资源,本文以59个栽培二粒小麦/节节麦和硬粒小麦/节节麦人工合成小麦,在室温（18℃）和低温（4℃）处理下测定萌发15天的幼苗形态指标,采用性状相对值（各性状低温与室温下测定值的比值）和隶属函数法相结合的方法,综合评价人工合成小麦品种的抗低温特性。结果表明,栽培二粒小麦/节节麦人工合成小麦的耐低温特性总体较硬粒小麦/节节麦人工合成小麦强;筛选出一批耐低温特性强的栽培二粒小麦-节节麦人工合成小麦材料,可用于小麦耐低温育种。     

Somaclonal variation and improvement in chilling tolerance in rice: changes in chilling-induced electrolyte leakage

Excised leaves of four rice varieties, ‘Facagro 57’, ‘Facagro 76’, ‘Kirundo 3’, ‘Kirundo 9’, were chilled for six days at 10/5°C day/night, along with 11 somaclonal families arising from three of these varieties, which had been selected over four generations for improved chilling tolerance. At the end of the chilling treatment, electrolyte leakage from leaf pieces was followed for 12 h and compared with an unchilled control. With unchilled leaves, no varietal differences nor a rise in leakage over time were observed. Chilling induced higher leakages in all varieties, except in ‘Kirundo 3’ at the time of first measurement, and a continuous rise over time was found in all varieties. Varietal differences were detected, ‘Kirundo 3’ being the least affected, followed by ‘Kirundo 9’ and ‘Facagro 76’, and finally ‘Facagro 57’, which coincides with their ranking for chilling tolerance established through chilling survival tests. The leakages were generally lower in the somaclonal families than in the variety they originated from in ‘Kirundo 9’ and ‘Facagro 76’, while the opposite was observed in ‘Kirundo 3’. The significance and usefulness of electrolyte leakage measurement for chilling tolerance screening, and the potentials of somaclonal variation for chilling tolerance improvement are discussed.     

Evaluation of the Low-Temperature Tolerance of Cotton Varieties in the Huang-Huai Region during Seed Germination

[Objective] To provide a theoretical foundation and germplasm resources for low-temperature-germination cotton breeding, the germination characteristics of 38 cotton varieties novel to or formerly widely planted in the Huang-Huai Region were evaluated under different low temperature stress conditions. [Method] Analysis of variance, the fuzzy membership function method, and cluster analysis were used to comprehensively evaluate the tolerance of these varieties to low temperature stress. [Result] As the temperature was lowered, germination rate, germination index, and vigor index exhibited a decreasing trend in all cotton varieties, but resistance to low temperature was significantly different among varieties. Cluster analysis divided the 38 varieties into three categories: highly resistant, resistant, and non-resistant. [Conclusion] Early-introduced varieties and those bred from early-introduced germplasm resources had weaker resistance to low temperature stress, with Stoneville and Deltapine series showing the lowest tolerance. The new transgenic insect-resistant cotton varieties SCRC 37 and SCRC 36 had the strongest resistance to low temperature stress.     

水稻全生育期耐盐资源初步筛选

为了筛选全生育期耐盐的水稻资源,本文对500份不同来源的国内外地方品种和旱稻资源用0.3%的NaCl盐溶液进行了苗期筛选,共获得34份苗期存活率和绿叶率大于50%的材料。对上述34份材料和前人报道的121份耐盐材料用0.3%和0.5%的NaCl进行了全生育期耐盐性筛选。0.3%的NaCl共筛选到7个品种的11个全生育期耐盐存活单株,而0.5%的NaCl仅筛选到1个品种中的1个存活单株。这些材料为耐盐机理研究和耐盐育种研究提供了材料基础。