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.     

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     

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.     

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.     

Temperature adaptation of tropical highland maize (Zea mays L.) during early growth and in controlled conditions

For economic and ecological reasons, the chilling tolerance of maize must be further improved. This seems to be possible by the introgression of tropical highland germplasm if chilling and heat tolerance can be combined to obtain a high yield consistency. Two adapted and two semi-exotic highland varieties were grown at 16, 25 and 30°C until the third and sixth leaf stage. Thereafter, some plants were transplanted and grown at 24°C in the glasshouse until anthesis. Exotic germplasm improved the leaf appearance and shoot growth during the early heterotrophic phase at all temperatures, with a marked advantage at low temperature. This superiority was almost completely lost during the succeeding autotrophic growth phase with some residual effects at low temperature and a marked relative retardation in leaf appearance and growth at high temperature. Relative growth rates (RGR) of exotic germplasm were not superior at low temperature or inferior at high temperature. At low temperature, their comparatively reduced leaf area ratio (LAR) was still compensated by a high net assimilation rate (NAR). Their expression of the latter trait was comparatively decreased at a high temperature, which explained the low RGR. Early growth at low and medium temperatures had similar effects on final leaf number for all varieties; a high temperature increased the final leaf number up to 20%, especially in exotic germplasm. In conclusion, the good early vigor of Mexican highland germplasm seems to be mainly restricted to the heterotrophic phase; a relation to adaptative mechanisms, such as a low LAR, must be overcome for an efficient utilization in conventional breeding programs.     

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.     

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.     

The Pattern of Dry-Matter Distribution during Development in Onion

Plant height, number of leaves, diameter and fresh weight of the bulbs, and the dry weights of the component plant parts of 3 onion cvs were measured weekly, starting 40 days after transplanting, up to maturity. Red Kano had singificantly more leaves, greater leaf area, larger bulbs and fresh and dry weights than Eclipsel Bermuda and Texas Grano.
Net Assimilation Rate (NAR), Relative Growth Rate (RGR), and Relative Leaf Growth Rate (RLGR) were generally high in the early stages of growth in all cvs and declined with plant age. Red Kano had much higher values than the other two. Crop Growth Rate (CGR) of tops was positive in the early stages of plant growth in all the cvs but decreased to negative values towards maturity which was due to a decrease in the dry weight of the leaf blades caused by decrease in leaf number. Red Kano and Texas Grano showed positive values throughout the experimental period. The higher CGR for the bulbs as compared to the blades was due to large quantities of carbohydrates which were translocated to the bulbs. Leaf Area Ratio (LAR) was constant in Red Kano , due to proportionate increase in leaf blade area and weight.
Results of all the growth characteristics showed that Red Kano was superior to the other cvs in attaining a larger bulb size due to large number of leaves and longer growing season, resulting in the translocation of more carbohydrates to the bulbs.     

Growth Analysis Using Classical and Curve-Fitting Methods in Relation to Productivity in Pearl Millet (Pennisetum americanum L. Leeke)

The factors controlling productivity (dry matter production) in a pearl millet ( Pennisetum americanum L. Leeke) hybrid BJ-104 and its inbred parents, J-104 and 5141-A , were investigated using the harvest interval and curve-fitting methods. During initial stages, the hybrid showed highest total dry weight, leaf dry weight and leaf area, than the inbred lines. However, with age these differences decreased considerably. The male parent attained total dry weight almost equal to the hybrid by d 45, whereas the female parent attained it by d59.
The derived growth parameters like RGR, LAR, LWR and SLA showed strong ontogenic decline. Further, considerable cultivar variations were also recorded. Importance of the growth parameters in determining productivity is discussed and it is emphasized that higher accumulation of dry matter during initial seedling stages may be an important factor.     

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 Using Classical and Functional Techniques in Relation to Soil Moisture in Mustard

A Reid experiment was conducted to study the effect of soil moisture on growth of two mustard cultivars using classical and functional techniques of growth analysis. Two soil moisture levels were irrigated at 10-day intervals and a rainfed control was included. Total dry matter (TDM), leaf area index (LAI) and leaf area duration (LAD) were significantly increased by irrigation at most of stages of growth. Starting from a lower value, LAI and LAD reached a peak and then gradually declined. Among the growth attributes, crop growth rate (CGR), leaf area ratio (LAR) and leaf weight ratio (LWR) increased significantly under irrigation. Net assimilation rate (NAR) decreased more in the irrigated plants than the rainfed plants at the later stages of growth. LAR and LWR declined throughout with increasing time and plant weight. Seed yield of the irrigated plants was positively correlated with the pre-flowering LAI and the post-flowering CGR and NAR. In the rainfed plants, seed yield was positively correlated with LAI and CGR at the post-flowering stage and negatively with the post-flowering NAR and pre-flowering LAR.     

Genetic analysis of,and selection for,factors affecting quantitative resistance to Xanthomonas campestris pv. oryzae in rice

Summary This study assessed 46 potato cultivars, breeding lines and Solanum spp. for heat-tolerance using short-term growth rates and carbon assimilation measurements of young in-vitro-derived plants. Plants of the 46 clones and species were transferred from greenhouse conditions to controlled conditions set at 33/25°C day/night with 12 h photosynthetic photon flux density (PPFD) at 430–450 mol m^-2s^-1 and an 8 h daylength extension (6 mol m^-2s^-1), to inhibit tuberization. Twenty eight accessions were also grown in a 20/10°C controlled environment. Plants were harvested after 10 and 20 days and dry weights of the plant components were measured for plant growth analysis. Gas exchange (leaf net photosynthesis and maintenance dark respiration) and leaf chlorophyll fluorescence parameters (O, P, and T) were measured at 30°C. Amongst the 30 accessions grown at both hot and cool temperatures, only two accessions (Yungay and AVRDC 1287.19) produced more dry weight in the hot chamber than the cool chamber. Hot/cool ratioss for net assimilation rate (NAR) and relative growth rate (RGR) exceoded unity in five and six accessions, respectively. For the 46 accessions grown under hot conditions, none had significantly greater values than those of the control clones for RGR and NAR. Differences between clones in maintenance respiration and net photosynthesis were more closely related to RGR, NAR, and total dry weight (TDWT) in clones which invested more dry weight in leaves and less in stems. Attributes of the chlorophyll fluorescence curve did not explain more of the clonal variation in RGR, NAR, and TDWT than did gas exchange parameters. No single gas exchange or fluorescence character explained more than 50% of the variability among clones for NAR, RGR, or TDWT, but combination of favourable attributes could improve potato heat tolerance in the future.     

Effects of Population on Physiological Growth Parameters of Pigeonpea Genotypes in Sole and Intercropped Stand with Sorghum CO 22

A field experiment was conducted during khariff 1984 in sandy clay loam soil under irrigated condition at the Tamil Nadu Agricultural University, Coimbatore, with a view (i) to find out the possibility of introducing short duration dwarf variety of sorghum CO 22 as an intercrop with pigeonpea genotypes, (ii) to study the effect of different plant population levels and intercropping of sorghum CO 22 on pigeonpea genotypes, and (iii) to find out compatible pigeonpea genotypes and plant population level for pigeonpea based intercropping system with sorghum CO 22.
It was observed that increased plant density significantly increased the dry matter production, leaf area index (LAI) and crop growth rate (CGR) during early stages and reduced the net assimilation rate (NAR), relative growth rate (RGR) and CCR during later part of the growth. Intercropping of sorghum CO 22 significantly reduced the dry matter production LAI, CGR, NAR and RGR. Plants in the intercropped stands recorded higher CGR, NAR and RGR during later part of the growth. Among pigeonpea genotypes CO 5 was much affected due to intercropping with sorghum CO 22.     

Influence of Soil Moisture on Growth, Water Use and Yield of Mustard

A field experiment was conducted to study the influence of soil moisture on growth, water use and yield of mustard ( Brassica juncea L. cv. Rai 5 ). Two soil moisture regimes were rainfed and irrigated at 10 days interval throughout the growing season. The total amount of water received as irrigation was 110 mm and as rainfall was 15 mm. Total dry matter per unit ground area, leaf area index (LAI), crop growth rate (CGR) and net assimilation rate (NAR) were increased and leaf area ratio (LAR) and specific leaf area (SLA) were decreased by irrigation. Chlorophyll content and relative leaf water content (RLWC) were increased by irrigation, but proline content was greater in the rainfed crop at both the flowering and pod-filling stages. Time taken to first flowering, duration of flowering, number of seeds/pod and harvest index were unaffected by irrigation. Plant height at harvest, number of pods/plant, seed yield and oil content of seeds were increased and 1000-seed weight was decreased by irrigation. The consumptive use of water increased with an increase in water supply, but the water use efficiency (WUE) was decreased.     

Water-use efficiency, leaf area and leaf gas exchange of cowpeas under mid-season drought

Ten cowpea (Vigna unguiculata L. “Walp.”) genotypes were grown in a growth chamber under well-watered conditions up to early flowering and were then either subjected to water deficit or were continually well-watered. Water deficit was induced by withholding irrigation until the soil water potential was −75 kPa, which was then maintained for 10 days. Variation in water use efficiency (WUE), leaf area, specific leaf area (SLA), leaf area ratio (LAR) and leaf gas exchange (i.e. assimilation, transpiration, stomata conductance and internal CO₂ concentration) in response to water deficit were investigated. Water deficit treatment reduced mean water use by 21%. This caused between 11 and more than 40% reduction of biomass across the genotypes. Reductions in biomass were due to decline in leaf gas exchange and leaf area during water deficit. Water deficit improved the WUE of two genotypes (IFH 27-8 and Lobia) by approximately 20%, but caused moderate to huge reductions in most genotypes. High relative water content (RWC) of leaves was maintained in some of the genotypes by stomata closure and a reduction of leaf area. Drought avoidance by maintaining high leaf water content was negatively associated with leaf area as well as SLA. High assimilation rate under water deficit was associated with high RWC. Decline in assimilation rate were due mainly to stomata closure, however, some evidence of non-stomatal regulation were also found. WUE and instantaneous water use efficiency (IWUE, a molar ratio of assimilation to transpiration) were not directly associated, but IWUE and leaf internal CO₂ concentration (c_i) were negatively related while c_i was also moderately related with SLA. Overall, significant genotypic variations in leaf gas exchange parameters were found, which can give some indications of superiority when comparing cowpea genotypes for agronomic fitness under drought. The lack of relationship between WUE and IWUE was due to the instantaneous measurement of leaf gas exchange, which can be corrected by calculations to reflect the entire season.     

Growth and Ionic Content of Quinoa Under Saline Irrigation

Drought and salinity are the most important abiotic stresses that affect plant's growth and productivity. The aim of the present work was to evaluate the effect of salt and water deficit on water relations, growth parameters and capacity to accumulate inorganic solutes in quinoa plants. An irrigation experiment was carried out in 2009 and 2010 in the Volturno river plain. Three treatments irrigated with fresh water (Q100, Q50 and Q25) and three irrigated with saline water (Q100S, Q50S and Q25S) were tested. For saline irrigation, water with an electrical conductivity of 22 dS m^?1 was used. Actual evapotranspiration (ET_a), water productivity (WP), biomass allocation, relative growth rate (RGR), net assimilation rate (NAR), specific leaf area, leaf area ratio and ions accumulation of quinoa plants were evaluated. WP and plant growth were not influenced by saline irrigation, as quinoa plants incorporated salt ions in the tissues (stems, roots, leaves) preserving seed quality. Treatment with a reduction in the irrigation water to 25 % of full irrigated treatment (Q25) caused an increase in WP and a reduced dry matter accumulation in the leaves. Quinoa plants (Q25) were initially negatively affected by severe drought with RGR and NAR reduction, and then, they adapted to it. Quinoa could be considered a drought tolerant crop that adapt photosynthetic rate to compensate for a reduced growth.     

Effects of Cadmium on Carbon and Nitrogen Assimilation in Shoots of Mungbean [Vigna radiata (L.) Wilczek] Seedlings

Increased cadmium (Cd) uptake from contaminated soils damages plant metabolism. The purpose of this study was to determine Cd‐induced time‐related changes in some shoot growth and physiological attributes, and their interrelationships in Cd‐tolerant (NM‐98) and sensitive (NM‐28) mungbean varieties. Shoot Cd and leaf chlorosis increased with a concomitant reduction in shoot dry weight, leaf area, relative growth rate (RGR), net assimilation rate (NAR) and relative leaf expansion rate. Reduction in transpiration rate (E) and stomatal conductance (g_s) and increase in substomatal CO₂ level (C_i), indicated that Cd reduced net photosynthesis (P_n) by reducing CO₂ fixation by Rubisco, albeit these changes were less pronounced in NM‐98. A positive correlation of chlorosis with shoot Cd, and negative relationships of chlorosis and shoot Cd with P_n revealed that Cd damages the photosynthetic apparatus in mungbean. Time course decrease in in vivo nitrate reductase activity (NRA) and an increase in soluble nitrate in NM‐28 revealed that Cd markedly hampers nitrogen assimilation. Positive correlations of RGR and NAR with P_n and NRA and negative ones with chlorosis, shoot dry weight, shoot Cd and C_i in NM‐98 suggested that mungbean sensitivity to Cd is due to perturbed C and N assimilation.     

Growth analysis in a reduced leaf mutant of common bean (Phaseolus vulgaris L.)

Summary A comparison between the Royal Red bean variety and a reduced leaf mutant on the basis of growth indices is reported. The mutants has lower leaf area index (LAI) and leaf area duration (LAD) (–43.7%), higher specific leaf weight (SLW) (on the mean +33.3%) and accumulates less dry matter (–7.7%) than the normal genotype. When the net assimilation rate (NAR) is considered, the mutant is superior to the normal (+62.3%). It is concluded that the unit area of the mutant leaves accumulates dry matter more efficiently than that of the corresponding normal variety.     

Recovery Strategy Following the Imposition of Episodic Soil Moisture Deficit in Stands of Peanut (Arachis hypogaea L.)

Peanut stands often face water deficits in the tropics and subtropics, especially in drought-prone areas of India. The effect of drought on peanut production has previously been studied. However, there is a lack of information on the post-stress recovery mechanism. The objective of this study was to investigate the recovery mechanism after relief of water stress. The effect of short-term drought applied (for 12 days) at the pre-flowering, peak flowering and pod-filling stages on chlorophyll (Chl) pigments, water use efficiency (W_ue), quantum yield (Q_y), root/shoot ratio (R:S), relative growth rate (RGR), net assimilation rate (NAR) and flower production during stress and subsequent post-stress recovery was examined. The leaf water potential (ψ_leaf) and leaf relative water content (RWC) in plants subjected to water deficit were reduced to 1/10 and 2/3, respectively, of the corresponding control values. Moisture deficit significantly reduced Chl a and b concentrations, the Chl a/b ratio, stomatal conductance, photosynthesis, W_ue and Q_y. However, a strong recovery of these traits was noted after rewatering, which led to onset of fresh growth on post-stress, with a marked increase in RGR and NAR and a flush of flowering. Drought significantly enhanced R:S, which accelerated post-stress recovery. Peanut stands exhibited excellent ecophysiological recovery with the post-stress onset of fresh growth. This strong recovery mechanism found in peanut stands suggests that peanut has high environmental plasticity.