Significant Differences In Leaf Area Research Articles

Influence of Intercropping Green Gram with Two Paddy Varieties on Growth, Yield and its Components to Increase Economic Returns

A field experiment was conducted at the Faculty of Agriculture, Eastern University, Sri Lanka to investigate the effects of intercropping green gram on the growth and yield parameters of two varieties of paddy; Suwandel (traditional variety) and At 307 (improved variety) during the period of July to November 2022. The experiment was laid out in a 2 x 2 Factorial Randomized Complete Block Design with four treatments as monocropping Suwandel (T1), intercropping Suwandel with green gram (T2), monocropping At 307 (T3) and intercropping At 307 with green gram (T4), that were replicated five times. Significant differences in leaf area, shoot dry weight, 1000 seeds weight and grain yield were observed in the paddy-green gram intercropping system compared to the monocropping of paddy. Significant synergistic responses were also observed among the treatments, where the leaf area and shoot dry weight were the highest in Suwandel + green gram intercropping system and the 1000 seeds weight was the highest in At 307-green gram intercropping system. However, the cost-benefit analysis revealed that the net profit received from Suwandel + green gram intercropping system was 36.6% higher than the At 307-green gram intercropping system. Therefore, it was evident from the present study that the Suwandel + green gram intercropping system is an environmentally friendly sustainable approach to grow paddy without synthetic fertilizers.

Yield and Physiological Response of Autumn King and Scarlet Royal Table Grapes to Cane and Spur Pruning Systems

The type of training system affects vine growth and productivity; however, there is a lack of knowledge on the suitability of pruning systems for some recently introduced (Vitis vinifera L.) cultivars. In this study, we provide the growers with science-based information about the response of two table grape variates to cane and spur-pruning systems to develop the best cultural practices. In 2013, a vineyard was established at Kearney Agriculture Research Center, Parlier, California using “Autumn King” and “Scarlet Royal” table grapes (Vitis vinifera L.) grafted on Freedom rootstock. The performance of the three-year-old vines was assessed under two pruning systems, Quadrilateral cordon training (spur-pruning) and Head training (cane pruning). Data from the 2016 and 2017 seasons showed no significant differences in leaf area, chlorophyll content, Normalized Difference Vegetation Index (NDVI), and pruning weight between the two pruning systems in both cultivars. In both seasons, marketable yield did not vary between the two pruning systems in the Scarlet Royal. However, Autumn King marketable yield was significantly reduced when using the Quadrilateral cordon training (spur-pruning). Petioles nutrient analysis at bloom showed a non-significant increase in nitrate content in the cane pruned vines of both varieties. No significant difference was observed in cluster weight, berry physical, or chemical composition. It seems that both training systems could be used for Scarlet Royal. However, the cane pruning system in Autumn King produced higher yield without affecting cluster and berry quality. The different responses of the two varieties could be due to the genetic background and growth behavior. Our data confirmed the notion that the different responses to the training methods by various grape varieties may involve the genetic background, growth behavior, as well as nutrient uptake and usage by the vines. Establishing the proper training system for each grape variety is essential.

Application of Fish Waste Fertilizer on the Growth of Maize (Zea mays)

Corn is an important cereal in the world and widely used as human consumption, livestock feed and even as raw material for industrial purposes. A study was carried out on the effect of fish waste fertilizer (FWF) on the growth of maize at UiTM Jasin Campus, Malacca. The experiment was carried out by using Randomized Complete Block Design (RCBD) based on 5 treatments and 5 replications. The control treatment (T1) was 100% of NPK fertilizer, treatment 2 (T2) was 30% of NPK + 70% FWF, treatment 3 (T3) was 50% of NPK + FWF, treatment 4 (T4) was 70% of NPK + 30% FWF and treatment 5 (T5) was 100% FWF. The corn variety used was Leckat 592 and different doses of organic fertilizer were applied 5 times. The parameters used in this study were plant height, number of leaves, leaf area, stem girth and chlorophyll content. In this experiment, treatment 3 (50% of NPK + FWF) and treatment 4 (70% of NPK + 30% FWF) showed significant difference in leaf area and stem girth parameters, respectively. However, there are no significant differences of the treatments on plant height, number of leaves, and chlorophyll content. NPK fertilizer showed the highest mean numbers for the three parameters. Thus, from this study, combination of NPK fertilizer with fish waste fertilizer showed some significant in the growth of corn.

Seedling growth and fall armyworm feeding preference influenced by dhurrin production in sorghum

Cyanogenic glucosides (CGs) play a key role in host-plant defense to insect feeding; however, the metabolic tradeoffs between synthesis of CGs and plant growth are not well understood. In this study, genetic mutants coupled with nondestructive phenotyping techniques were used to study the impact of the CG dhurrin on fall armyworm [Spodoptera frugiperda (J.E. Smith)] (FAW) feeding and plant growth in sorghum [Sorghum bicolor (L.) Moench]. A genetic mutation in CYP79A1 gene that disrupts dhurrin biosynthesis was used to develop sets of near-isogenic lines (NILs) with contrasting dhurrin contents in the Tx623 bmr6 genetic background. The NILs were evaluated for differences in plant growth and FAW feeding damage in replicated greenhouse and field trials. Greenhouse studies showed that dhurrin-free Tx623 bmr6 cyp79a1 plants grew more quickly than wild-type plants but were more susceptible to insect feeding based on changes in green plant area (GPA), total leaf area, and total dry weight over time. The NILs exhibited similar patterns of growth in field trials with significant differences in leaf area and dry weight of dhurrin-free plants between the infested and non-infested treatments. Taken together, these studies reveal a significant metabolic tradeoff between CG biosynthesis and plant growth in sorghum seedlings. Disruption of dhurrin biosynthesis produces plants with higher growth rates than wild-type plants but these plants have greater susceptibility to FAW feeding.

Impacts of soil fertility management on productivity and economics of rice and fodder intercropping systems under rainfed conditions in Odisha, India

Under small and marginal farm conditions, allocation of land exclusively for forages is not possible. Hence, integration of forages in existing crop geometry can ensure production of grain and fodder, simultaneously under rainfed conditions. A field experiment was conducted to study the effect of different nutrient management practices on rice and fodder intercropping systems under rainfed conditions during 2015–2017. The intercropping system comprised (i) sole rice (R), (ii) rice and cowpea (5:2) (CP) and (iii) rice and ricebean (5:2) (RB) whereas the different nutrient management practices comprised (i) application of farm yard manure (FYM) at 5 t ha–1 (farmers’ practice) (N1), (ii) application of inorganic fertilizer (recommended dose of fertilizer (RDF) of rice, 60:30:30 kg ha–1 of N:P2O5:K2O) (N2) and (iii) application of both FYM at 5 t ha–1 and 50% of RDF inorganic fertilizer (N3). The results of the experiment revealed that the growth attribute such as leaf area was influenced significantly when fodder crops were taken as intercrops because rice plant was getting more nitrogen from soil due to nitrogen fixation of leguminous fodder crops. Among the nutrient management practices, significant differences in leaf area were found beween N2 and N1, and between N3 and N1 treatments. However, regarding total number of effective tillers, significant differences were found neither between nutrient management practices nor between cropping systems. The rice equivalent yield (REY) based on price (REYP) was found to be significantly lower in CP (2 615 kg ha–1; –6.4%) and RB intercropping systems (2 571 kg ha–1; –8.0%) than in R monocropping system (2 794 kg ha–1). However, the REY based on energy (REYE) of CP (2 999 kg ha–1; +7.3%) and RB (2 960 kg ha–1; +5.9%) were found to be significantly higher than that of R (2 794 kg ha–1) irrespective of nutrient management practices. Between different nutrient management practices, the N3 treatment recorded the highest REYP and REYE which was at par with the N2 treatment and significantly higher than the N1 treatment irrespective of cropping systems. The combined application of both organic and inorganic sources of nutrients helped to supply nutrients throughout the growing season, which led to improved growth parameters and rice yield. The R monocropping system resulted in more income and rain water use efficiency (RWUE) closely followed by rice and fodder intercropping systems. However, the REYE and energy use efficiency (EUE) of rice and fodder intercropping systems were higher than those of R. Also, fodder helped to meet the requirement of cattle feeding in the off-season. Hence, the intercropping system is advocated in the study zone. Further study can be done on ecosystem services and carbon sequestration potential of the intercropping system, as well as the system’s coping ability in response to short drought through observing periodic soil moisture regime in root zone.

Response of varieties of maize to bio-fertilization of Bread yeast (Saccharomyces Cerevisiae L.)

A field experiment was conducted in experimental field of Department Of Field Crops- Agriculture College/ University Of Anbar (Abu-Ghariab) during spring and autumn season of 2016 to study the effect of three maize cultivars (Massara, Sarah, and Maha) and four levels from bread yeast extract (Saccharomyces Cervisiae L.) 0, 10, 20, and 30 g L-1 were sprayed on the foliar. The two factors of the study were organized as split plot within RCBD with three replications. However, cultivars occupied the main plots while the yeast levels were put in the sub plots. The results of the study showed the following: In spring season, the level 30 g L-1 was significantly in plant height, number of ears, plant dry matter weight, weight of 500 grain, and the level 20 g L-1 gave significant differences in leaf area. While level 10 g L-1 showed a significant difference in grain in number a row total and grain yield of. In autumn season, 30 g L-1 level recorded significant in number of ears, leaf area and plant dry matter weight. While the level of 20 g L-1 was superior in plant height, number of rows and total yield grain. However, the level of 10 g L-1 was prominent in 500 grain weight and number of rows. In the spring season, Maha cultivar was significantly superior in the plant height, plant dry matter weight, and number of grains in row. While Sarah cultivar was significantly superior in leaf area, number ears in plant, and number of rows in ear, weight of 500 grains, total yield grain. As for autumn season, Massara cultivar was significantly superior in leaf area number of ear, and plant dry matter weight. While Sarah cultivar was significantly prominent in number of rows in ear). While Maha cultivar was significantly superior in plant height, weight of 500 grains and total yield. As for the interaction between the study two factors, it significantly affected in most studied traits, however Sarah cultivar plants that treated with 30 g L-1 gave the highest values of most traits means and for the two seasons of the study.

TheEffect of Color Plastic Mulches onGrowth, Yield and Quality of Two Hybrids of Summer Squash (cucurbita pepo l.)

This experiment was carried out at the vegetable research farm of Horticulture Department/ Faculty of Agriculture /Duhok University on two hybrids of summer squash during spring in the season of 2014, to study the effect of five color plastic mulches (without cover, transparent, black, red and blue) on two hybrids of summer squash (Amjed and Alexandra F1). The results showed that covers plastic mulches led to positive significant differences in leaf area (cm2), leaves chlorophyll content%, , fruit number/plant, early yield and total yield as well as fruit weight (g ), fruit length (cm) and fruit diameter (mm) as compared to without cover. There were no significant differences between the two hybrids in all detected traits. The interaction between covers plastic mulches and two hybrids was significantly enhanced all detected traits, since summer squash (Alexandra hybrid) covered with transparent plastic mulch were characterized by the highest values of leaf area (cm2), leaves chlorophyll content% and fruit diameter (mm), and summer squash (Amjed hybrid) covered with blue plastic mulch gave positive significant of fruit number/plant and total yields ton/ hectare

First Report of a 16SrII-C Phytoplasma Associated with Asymptomatic Acid Lime (Citrus aurantifolia) in Brazil.

At present, the principal bacterial disease of citrus in Brazil is Huanglongbing, caused by the alpha-proteobacterium 'Candidatus Liberibacter spp.' (although a phytoplasma of the 16SrIX group is also associated with this disease [4]). While there is a wide diversity of phytoplasmas in crop species in Brazil (3), there have been no reports of symptoms associated with phytoplasma in Brazilian citrus. Asymptomatic infections of citrus cannot be excluded as a possibility and such plants could serve as a reservoir of phytoplasma inoculum. The aim of this study was to assess the presence of phytoplasma in asymptomatic Citrus aurantifolia (acid lime) in Brazil. Thirty-three leaf samples (young leaves from the upper canopies) were randomly collected from different plants in the states of Minas Gerais (n = 23), Santa Catarina (n = 2), and São Paulo (n = 8). Two additional samples of C. limonia ('Rangpur' lime) and one of C. latifolia ('Persian' or 'Tahiti' lime) were collected in Minas Gerais. Total DNA extraction was performed using NucleoSpin Plant II Kit (Macherey-Nagel) according to the manufacturer's recommendations. PCR was carried out with a universal P1/P7 primer set followed by nested primers R16F2n/R16R2 (2). Additionally, direct PCR was performed using primers specific for phytoplasma immune-dominant membrane protein IMP3F/IMP3R (1). 'Rangpur' and 'Tahiti' lime were not infected with phytoplasma. Of the C. aurantifolia samples, 52% were positive for phytoplasma in the direct and nested PCR assays. The numbers of positive samples in Minas Gerais, Santa Catarina, and São Paulo states were 12, 1, and 4, respectively. Of these, five were selected for DNA purification and 1,246-bp fragments were ligated to the pGEM T-easy vector (Promega) and partial 16Sr DNA was sequenced. Nucleotide sequences of Brazilian phytoplasma strains BR:MG:FNS10:2011, BR:MG:FNS53:2011, BR:SP:FNS73:2011, BR:SC:FNS86:2011, and BR:MG:FNS126:2012 (GenBank Accession Nos. KJ158173, KJ158174, KJ158175, KJ158176, and KJ158177, respectively) were subjected to RFLP analyses. The 16S rDNA RFLP in silico patterns for the five strains were identical to each other and to Cactus witches'-broom phytoplasma (16SrII-C subgroup, AJ293216). In addition, the highest similarity coefficient (5) and nucleotide sequence identity of Brazilian phytoplasma strains were 0.99 and 99%, respectively, with Cactus witches'-broom phytoplasma. PCR-RFLP analyses using the enzymes Bstu I, EcoR I, and Hpa II were consistent with RFLP in silico results, showing the same pattern as the 16SrII-C subgroup. Phylogenetic analyses based on 16S rDNA sequences (1,246 bp) demonstrated that all the Brazilian strains grouped in the same clade with other representative sequences from the 16S rDNAII group. To confirm the absence of any macroscopic symptoms, morphological characteristics of 10 uninfected and 10 phytoplasma-infected plants randomly selected from a single field in Minas Gerais were analyzed. There were no significant differences in leaf area, stalk diameter, or numbers of leaves, flowers, or fruits per branch. To our knowledge, this is the first report of the 16SrII-C subgroup phytoplasma associated with C. aurantifolia in Brazil, and the first report of asymptomatic citrus plants infected with phytoplasma.

Effect of remediation on growth parameters, grain and dry matter yield of soybean (Glycine max) in crude oil polluted ultisols in Ogoni Land, South Eastern Nigeria

The effectiveness of cow dung, poultry manure, NPK (mineral fertilizers) and municipal waste compost which were the easily accessible materials in the remediation of crude oil polluted soils in Ogoni, Rivers state was assessed using soybean as a test crop. A simple factorial field experiment arranged into a randomized complete block design with six treatments was used. Poultry manure gave the highest emergence of 79 and 74.62% at both seasons followed by NPK, cow dung, municipal waste compost and control. The highest plant height of 11.48 and 19.18 cm at four and six weeks after planting (WAP); and 12.70 and 24.70 cm at 4/6 WAP for both seasons were obtained in plots treated with poultry manure. NPK (15:15:15) fertilizer gave the largest leaf area (12.70 and 12.95 cm2) and (14.43 and 14.56 cm2) at 4 and 6 WAP for both seasons, respectively followed by poultry manure (11.80 and 11.93 cm2) and (13.72 and 12.8 cm2. Poultry manure gave the highest grain yield per hectare of 2,800 and 3,875 kg ha-1) for both seasons. NPK had the highest dry matter yield at both seasons (8,500 and 8,000 kg ha-1), followed by poultry manure (7,000 and 7,500 kg ha-1). Since there were no significant differences in leaf area between NPK, poultry manure and cow dung treatments, the results indicate that poultry manure is the best remediation material for crude oil polluted soils in which soybean is planted. Key words : Crude oil, polluted soils, soy bean, remediation material, poultry manure, NPK fertilizers, grain yield, plant height, leaf area, Niger delta.

Phenotypic Plasticity in the Invasion of Crofton Weed (Eupatorium adenophorum) in China

Phenotypic plasticity and rapid evolution are two important strategies by which invasive species adapt to a wide range of environments and consequently are closely associated with plant invasion. To test their importance in invasion success of Crofton weed, we examined the phenotypic response and genetic variation of the weed by conducting a field investigation, common garden experiments, and intersimple sequence repeat (ISSR) marker analysis on 16 populations in China. Molecular markers revealed low genetic variation among and within the sampled populations. There were significant differences in leaf area (LA), specific leaf area (SLA), and seed number (SN) among field populations, and plasticity index (PIv) for LA, SLA, and SN were 0.62, 0.46 and 0.85, respectively. Regression analyses revealed a significant quadratic effect of latitude of population origin on LA, SLA, and SN based on field data but not on traits in the common garden experiments (greenhouse and open air). Plants from different populations showed similar reaction norms across the two common gardens for functional traits. LA, SLA, aboveground biomass, plant height at harvest, first flowering day, and life span were higher in the greenhouse than in the open-air garden, whereas SN was lower. Growth conditions (greenhouse vs. open air) and the interactions between growth condition and population origin significantly affect plant traits. The combined evidence suggests high phenotypic plasticity but low genetically based variation for functional traits of Crofton weed in the invaded range. Therefore, we suggest that phenotypic plasticity is the primary strategy for Crofton weed as an aggressive invader that can adapt to diverse environments in China.

Effect of Remediation on Growth Parameters, Grain and Dry Matter Yield of Soybean (Glycine max) in Crude Oil Polluted Soils in Ogoni Land, South Eastern Nigeria

The effectiveness of organic and inorganic fertilizers (cow dung, poultry manure, NPK and municipal waste compost) in the remediation of crude oil polluted soil in Ogoni, Rivers state was assessed using soybean as a test crop. A simple factorial field experiment arranged into a randomized complete block design with four replicates and twenty-four experimental plot with six treatments was used. Plot treated with poultry manure recorded the highest value of emergence (79 and 74.62%) at both seasons followed by NPK (73 and 68.32%), Cow dung (69.37 and 67.92%), municipal waste compost (66.25 and 65.3%), respectively. The least emergence (56.50 and 60%) was observed in the control for both seasons. Soybean plants height were highest in plot treated with poultry manure 4 and 6 WAP (11.48 and 12.70 cm) and (24.70 and 19.18 cm) for both seasons. There was decreased in the following order NPK (10.98 and 11.58 cm) and (23.28 and 17.05 cm), cow dung (10.18 and 11.96 cm) and (20.88 and 17.10 cm), municipal waste compost (10.03 and 11.08 cm) and (18.58 and 16.88 cm), No pollution plot (9.80 and 10.65 cm) and (16.43 and 16.70 cm) and then the control (polluted with no amendment) (8.65 and 9.33 cm) and (14.85 and 14.50 cm). NPK had the largest leaf area (12.95 and 12.70 cm2) and (14.43 and 14.56 cm2) 4 and 6WAP for both seasons, followed by poultry manure (11.80 and 11.93 cm2) and (13.72 and 12.8 cm2), municipal waste compost (12.29 and 11.53 cm2) and (12.93 and 12.49 cm2), cow dung (11.45 and 11.13 cm2) and (13.06 and 12.51 cm2), respectively. Poultry manure gave the highest grain yield per hectare (2,800 and 3,875 kg ha-1) for both seasons followed by NPK (2,220 and 2,687 kg ha-1), municipal waste compost (2,000 and 2,190 kg ha-1) and no pollution (1,575 and 1,780 kg ha-1) for both season. NPK had the highest dry matter yield at both season (8,500 and 8,000 kg ha-1), respectively. This was followed by poultry manure (7,000 and 7,500 kg ha-1), cow dung (6,000 and 7,000 kg ha-1), municipal waste compost (5,500 and 4,500 kg ha-1) and no pollution (3,000 and 2,500 kg ha-1), respectively. The least dry matter yield was observed in the control (2,500 and 2,000 kg ha-1) for both seasons. There was improvement in the dry matter yield value of poultry manure (7,500 kg ha-1) and cow dung (7,000 kg ha-1) at late planting when compared to that of early planting. Since, there were no significant differences in leaf area between NPK, poultry manure and cow dung treatments, the results indicate poultry manure as a remediation material in crude oil polluted soils planted to soybean.

EFFECTS OF PLANT DENSITY ON ROOT YIELD AND LEAF AREA IN CHICORY (CICHORIUM INTYBUS L.)

Chicory (Cichorium intybus L.) belonging to the Asteraceae family has prominent medicinal properties and its root has been reported to be the most abundant source of inulin which has valuable applications in pharmaceutical and food industries. It also contains important compounds such as bitter sesquiterpene lactones, cumarins, flavonoids and vitamins. Due to its various uses as a vegetable and a medicinal plant and considering that it is not yet cultivated in Iran, we endeavored to investigate the effects of plant density on the root yield and characteristics as well as leaf area in two cultivars of chicory. The experiment was conducted in Khalat-Pushan Agricultural Research Station (KARS), University of Tabriz, Tabriz, Iran. Four intra-row spacing (5, 10, 15, and 20 cm) and two cultivars ('Pagana' and 'Yellow Star') were compared in a randomized complete block design with three replications. The results showed significant differences in leaf area per plant between cultivars and plant densities. The intra-row distance of 20 cm and 'Pagana' had the highest leaf area per plant. There were significant differences in root length and diameter with plant density but not between cultivars. Moreover, differences in root fresh weight per plant either between cultivars or plant density appeared to be significant. In conclusion, the cultivar 'Pagana' was identified as the highest in root fresh weight per plant and when cultivated at 15 and 20 cm spacings.

SSR linkage map construction and QTL mapping for leaf area in maize

Maize (Zea mays L.) leaf is the main organ for photosynthesis. The area of leaves (especially the ear-leaf and the two leaves above and below the ear-leaf) plays a vital role in dry matter accumulation and grain yield. Therefore, genetic information on leaf area has a theoretical significance for breeding maize with high yield. In this study, a genetic linkage map composing of 184 simple sequence repeat (SSR) markers was constructed based on an F8 recombinant inbred line (RIL) population, which was derived from a cross between 478 and W312. The parents showed a significant difference in leaf area. The map covers 2084.1 cM with an average interval of 11.3 cM. QTLs for leaf area were identified under two-year's field experiments. Totally 7 QTLs were detected in two years, among which 4 QTLs were detected in 2006 and 3 QTLs in 2007. A major QTL on chromosome 2 (between umc1542 and umc1518) were detected in both 2006 and 2007. It explains 12.5% and 17.3% of the phenotypic variation, respectively. This locus can be used as a potental marker for improving maize leaf growth through marker assisted selection (MAS) approach.

Effects of Cultivation Systems on the Growth, and Essential Oil Content and Composition of Valerian

ABSTRACT The growth and essential oil production of valerian (Valeriana officinalis L. var. common) growing in aeroponic, floating, growing media (a perlite and vermiculite mix), and soil systems were accessed by measuring biomass production and essential oil content and composition. The highest fresh weight of both leaves (802 g plant−1) and roots (364.5 g plant-1) was obtained in the floating media system. No significant difference in leaf area between the floating and growing media systems was observed, but comparative leaf area was reduced considerably in the aeroponics and soil systems. Both photosynthesis and stomatal conductance were increased in the floating and growing media systems, as compared with the aeroponics and soil systems, along with the concentration of essential oil. The major constituents of essential oil were bornyl acetate, valerenal, comphene, trans-caryophyllene, cis-ocimen, α-fenchen, and δ-elemene, although the relative proportion of each constituent varied with treatment. The concentration of bornyl acetate was highest (32.1% of total oil) in the floating system, some 56.5% higher than the concentration the soil. Growing valerian plants in a soil system induced the production of valerenal, and this constituent was higher in the soil systems than in the other growth systems. The results suggest that under a controlled environment, both floating and growing media systems could be promising approaches for obtaining higher root yields and oil productions in valerian.

Suitability of wood fiber substrates for production of vegetable transplants II.: The effect of wood fiber substrates and their volume weights on the growth of tomato transplants

The influence of wood fiber substrates (WFS) and their volume weights (VW) on the growth of tomato transplants ( Lycopersicon lycopersicum (L.) Karst. ex Farw.) were examined. No significant differences were observed for the absolute and relative growth rate of tomato transplants cultivated in WFS as compared to white peat (WP). Particularly in WFS plants showed a well developed root system. When the tomato transplants were cultivated in spring increases of VW led to a reduction of root growth, but no significant differences were observed for other plant parameters. In summer differences between weakly and strongly compacted substrate treatments for fresh mass of leaf and stem for both WFS were found. The coarse WFS also showed a significant difference in leaf area for these two treatments. Weakly compressed substrate had a faster decrease of matric potential in summer. WFS are suitable for cultivation of vegetable transplants and are a good alternative for peat-based substrates. When filling containers, moderate compression of WFS is recommended.

Response of a mature Pinus laricio plantation to a three-year restriction of water supply: structural and functional acclimation to drought.

The response of mature forest stands to a reduction in water availability has received little attention. In particular, the extent to which a short-term reduction in gas exchange can be alleviated in the long-term by acclimation processes is not well understood. We studied the impact of a severe reduction in water availability on the water relations and growth of 35-year-old Pinus laricio Poiret. trees in a replicated experiment. Sapwood and needle increments, soil and tree water status, stand transpiration, xylem embolism and plant hydraulic architecture were monitored over a 3-year period in control and drought-treated plots. Needle length was reduced in drought-treated trees by 30, 19 and 29%, and sapwood increments by 50, 27 and 24% over the 3 years. Drought did not result in tree mortality or in extensive xylem embolism or foliage dieback. On the contrary, a conservative water-use strategy was observed, because minimum leaf water potentials did not differ between treatments or over the season. Plant hydraulic resistance was also unaffected by restricted water availability. Stand transpiration was strongly reduced by drought treatment over the summer, but not during the winter, despite significant differences in leaf area between control and drought-treated trees, implying higher transpiration rates per unit leaf area in the droughted plants. This suggests that water transport capacity, rather than the amount of leaf area, controlled stand transpiration, which is at variance with expectations based on experiments with seedlings and short-term experiments with mature trees.

Effects of irradiance on growth and flowering in the shade plant, cineraria

SummaryEffects of total irradiance on growth and flowering were studied in cineraria cv. Cindy Blue grown under warm (mean 21°C) glasshouse conditions. Efficiency of light conversion for leaf and shoot dry weight increase were reduced from 0.08 to 0.02 as the mean daily light integral increased from 0.9 to 4.4 MJ m‐2 day‐1 but no significant difference in leaf area were associated with this. Specific leaf area decreased exponentially from 0.07 to 0.02 m2g1 over the cumulative irradiance range 23 to 127 MJ m‐2 after the start of treatments and thereafter remained stable. A light integral of 19.2 MJ m‐2 were required for initiation of one leaf in plants grown under a daily integral of 4.4 MJ m‐2 day‐1, as compared with only 5.1 MJ m‐2day‐1 required per leaf in plants grown at less than 0.9 MJ m‐2day‐1. Neither chronological duration of juvenile development nor leaf number below the flower was affected by irradiance. However, as the rate of leaf initiation increased with irradiance up to 2.4 MJ m‐2day‐1 so the rate of progress to flower visibility increased linearly with irradiance over the same range. This rate then remained constant from 2.4 to 4.4 MJ m‐2day‐1. Length of the main flowering shoot decreased and the number of flowering shoots increased as irradiance increased from 0.9 to 2.4 MJ m‐2 day‐1 and then remained unchanged by further increases in irradiance.

Shoot and Root Development of Tall and Hard Fescues in Two Different Soils

AbstractTall (Festuca arundinacea Schreb.) and hard fescue [Festuca ovina var. longifolia (L.) Koch] are among the most widely sown grasses used to stabilize disturbed soils in both the cool‐humid and transition climatic zones of the USA. Our objective was to evaluate the root and shoot development of two turfgrasses grown in sand and silt loam soils. Significant differences in leaf area, plant height, shoot and root dry matter, root depth (RD), root branching (RB), and root length (RL) were recorded with tall fescue compared with hard fescue. Greater leaf area, leaf number, plant height, shoot and root dry matter, and RL were observed when the grasses were grown in a silt loam soil. Greater RD and root/shoot ratio were recorded in sandy soil. Both turfgrass species and soil texture affected leaf area, leaf number, plant height, shoot dry matter, RD, RL, RB, root dry matter, and the root/shoot ratio. Significant correlations were obtained for shoot dry matter with root dry matter and RL; leaf area with shoot dry matter and root dry matter; root dry matter with TRL and RB; RD with root/shoot ratio; RL with leaf area; and RB with TRL and RD. Turfgrasses and soil types had an significant impact on shoot and root development. A greater understanding of early root development for these grasses will assist in developing techniques for establishment and persistence under disturbed soils and adverse climatic conditions.

Response to water stress of Italian alder seedlings from diverse geographic origins

The morphological and physiological response to water stress was studied in 2-year-old potted Italian alder (Alnuscordata Loisel.) seedlings. Leaf area, transpiration, stomatal conductance, and xylem water potential were measured during May 1987 on seedlings from five geographic sources grown (i) with soil water content close to field capacity and (ii) with a severe drought. Significant differences in leaf area were found, at the end of the experiment, between drought-stressed and well-watered plants. As drought progressed, plants displayed a reduction of xylem water potentials and a decrease in stomatal conductance. However, transpiration did not stop completely, and seedlings were not able to maintain a favourable internal water status. Osmotic potentials for the undiluted cell sap, estimated from pressure–volume curves, were between −0.9 and −1.3 MPa. In June 1988, a similar experiment was carried out using seedlings from only one geographic source. A simultaneous decrease of transpiration, xylem potential, and net photosynthesis was observed in seedlings subjected to the drought treatment. During both experiments, a recovery of physiological parameters was observed, after rewatering. Some differences between provenances were detected. The provenance from Corsica showed the greatest sensitivity to water stress; a seed source from the province of Avellino (Campania, south Italy) was able to maintain a more favourable internal water status, as drought progressed.

Grapefruit Leaf and Fruit Growth in Response to Drip, Microsprinkler, and Overhead Sprinkler Irrigation

Abstract Fruit and vegetative growth of 21-year-old grapefruit (Citrus paradisi Macf.) trees on well-drained sandy soil was studied in central Florida. Drip, microsprinkler, and overhead sprinkler irrigation was compared at two levels of irrigation (150 and 450 mm·year−1). Significant differences in leaf area, fruit size, fruit growth, new flush growth, and canopy area were found with different irrigation systems applying similar amounts of water. Growth was improved by irrigation even in a year of high rainfall (1410 mm). With mature trees, drip systems promoted the least growth, while overhead sprinkler systems promoted the most. Leaf fresh and dry weights and individual leaf areas in the overhead sprinkler treatments were 40% to 50% greater than in the drip or nonirrigated treatments, while specific leaf weight and leaf water content per unit dry weight were similar for all treatments. Final fruit size and tree canopy area were 9% to 20% greater in the overhead sprinkler treatments than in the corresponding drip or nonirrigated treatments. Responses to microsprinklers were generally intermediate between the overhead sprinkler and the drip treatments. Because of the low soil area coverage, applying water at the higher rate with the drip system did not improve growth as well as the overhead system at the lower rate. With mature grapefruit trees under central Florida conditions, systems providing greater soil area coverage gave better leaf and fruit growth than systems providing less soil coverage.