Ground Dry Weight Research Articles

INFLUÊNCIA DO SOMBREAMENTO NA PRODUÇÃO DE MUDAS DE ANGELIM PEDRA (DINIZIA EXCELSA DUCKE)

Este experimento foi instalado no viveiro da reserva Adolfo Ducke, Amazonas, Brasil, com o objetivo de verificar a influência do sombreamento na produção de mudas de Dinizia excelsa.Os níveis de sombreamento (30, 50 e 70%) foram obtidos por meio de teias de poliolefinas de cor preta. Trinta, sessenta e noventa dias após a permanência das mudas no viveiro, procederam-se as avaliações de altura, diàmetro à altura do colo, peso seco da parte aérea e do sistema radicular. Foram obtidos os seguintes resultados: a) com relação aos períodos, verificou-se que a altura foi maior quando as mudas foram retiradas com 90 dias; para os demais parâmetros analisados, não se verificou influência significativa; b) as mudas que atingiram altura mais elevada foram as produzidas sob 30% e 50% de sombreamento; observou-se decréscimo no diàmetro do colo e na altura das mudas com o sombreamento de 70%; c) as mudas apresentaram maiores valores de peso de matéria seca da parte aérea e do sistema radicular quando produzidas com pouco sombreamento (30 e 50%).

VEGETATIVE GROWTH AND REPRODUCTIVE POTENTIAL OF THREE TYPES OF MICROPROPAGATED RED RASPBERRY NURSERY STOCKS.

The growth and fruiting of 3 types of micropropagated red raspberry plants were compared. The 3 types of nursery material included: 1) Stage 4 (S-4) - 10-15 cm tall, actively growing plants; 2) dormant Stage 4 (DS-4); and 3) nursery matured (NM) - S-4 plants that are grown for 8-12 weeks in the field. On 1 Apr. 1991, `Redwing' plants of each type were planted 0.6 m apart in ridged, drip-irrigated, and straw-mulched rows spaced 3 m apart. Fruit harvest began on 16 Aug. and continued until 28 Oct. On 12 Nov., the above ground portion of each plant was harvested for measurements of plant growth. The S-4 and NM plants had the highest fruit yields (number and weight), and the S-4 plants had the largest fruit size. NM plants had the first ripe fruit followed 4 days later by S-4 plants and 10 days later by DS-4 plants. The NM and S-4 plants had the greatest cane lengths and diameters. The S-4 and DS-4 plants had the largest above ground dry weights. The DS-4 plants produced the largest number of canes.

A replacement series evaluation of competition between velvetleaf (Abutilon theophrasti) and soybean (Glycine max)

Summary:We examined relative competition abilities of velvetleaf (Abutilon theophrasti) and soybean (Glycine max) grown in a replacement series near Ames, Iowa, U.S.A. in 1986 and 1987. Relative above ground dry weight of soybean in mixtures was higher than expected from mono culture values early in the growing season but lower than expected later in the season, whereas velvetleaf had higher than expected values later in the season. Velvetleaf depressed seed yield of soybean in all mixtures; relative seed yield of velvetleaf was greater in all mixtures than in monoculture. Relative growth rate (RGR), leaf area ratio (LAR) and net assimilation rate (NAR) of soybean did not differ significantly among mixtures and generally decreased over the growing season. Velvetleaf exhibited no consistent differences among mixtures in RGR, LAR, and NAR. Net assimilation rate of velvetleaf was constant over most of the growing season. Relative growth rate and LAR of velvetleaf were highest early in the season and then progressively declined. Velvetleaf had higher NAR and higher RGR than soybean early in the season; LAR of velvetleaf was lower than LAR of soybean over most of the season. Velvetleaf and soybean did not significantly interfere with each other early in the growing season, but velvetleaf gained resources at the expense of soybean during the middle and later parts of the season.

TEMPERATURE DURING EARLY DEVELOPMENT AFFECTS PLANT MORPHOLOGY OF BEGONIA × HIEMALIS

The effect of temperature during the initial long day period on morphology and plant dry weight was determined for Begonia × hiemalis `Hilda'. Multistem cuttings were planted in 10 cm pots and grown at 13°, 16°, 19°, 22°, 25° or 28°C. The day length was 16 hours at an irradiance level of 280 ± 20 μmol·m-2s-1. After 21 days, the plants were moved to a greenhouse maintained at 20° ± 2°C and short days of 10 hours at 125 ± 20 μmol·m-2s-1. The plants were grown under short days for 14 days and then moved to a day length of 16 hours. At data collection 21 days later (56 days from planting), plant height averaged 185 mm for plants initially grown at 13°, 16°, 19° or 22°C while pants originally grown at 25° and 28°C were 40 and 78 mm shorter than plants started at lower temperatures. The mean number of shoots was 4 on plants exposed to 16°, 19°, 22° or 25°C during early development and decrease to 3 shoots for plants grown initially at 13° or 28°C. The average flower number on the main shoot was similar for plants first exposed to low and intermediate temperatures but decreased rapidly to 0 for plants with early exposure to 28°C. Plants in treatments with early temperatures of 19° or 22°C had the largest above ground dry weight at an average 460 mg.

Dynamics of root and shoot growth of barley under various levels of salinity and water stress

Response of barley to water stress at different growth stages at various levels of soil salinity was studied in cylindrical wooden containers (1.1 m long and 0.6 m in diamer). The treatments consisted of three salinity levels (low = S 1, medium = S 2 and high = S 3) and two irrigation treatments, no water stress at any given growth stage and plants exposed to water stress at either tillering, vegetative, flowering or seed formation stage and normally irrigated in the other stages. Comparison in above-ground dry weights indicated a significant variation ( P = 0.05) between different treatments at each sampling date. The interaction between salinity and water stress was also significant. Maximum reduction in shoot dry weight was 70% under S 3 treatment when the plants were imposed to water stress in the vegetative growth stage. The relative reductions in shoot dry weights due to salinity at the vegetative growth stage were 33% and 46% for S 2 and S 3, respectively, in comparison to S 1. Root dry weights significantly varied between different treatments. The highest reduction in root dry weights was recorded when the plants were exposed to water stress and/or salinity at the vegetative growth stage. Linear relations between evapotranspiration and above-ground dry weights, grain yields and root dry weights were obtained. Regardless of water stress or salinity levels, barley grain, above ground dry weights, and root dry weights were correlated with evapotranspiration.

Plastic Energy Allocation Patterns in Plantago Coronopus

Energy allocation patterns in Plantago coronopus L. were investigated in greenhouse experiments and in natural populations. In the greenhouse, plants originating from one population were grown under a range of conditions. All plants behaved as monocarpic annuals and were harvested at full reproductive maturity; thus, observed differences in energy allocation patterns were not ontogenetically based. Density strongly influenced energy allocation but nutrients exerted little effect. Reproductive allocation decreased significantly with increasing density (p <0.001). It ranged from 31-41% of above ground dry weight. Mean reproductive allocation was correlated (r = +0.85, p <0.01) with mean above-ground dry weight of plants under different conditions. Three isolated field populations differed significantly in energy allocation patterns; these patterns could be interpreted as strategic responses to site differences. Reproductive allocation was significantly correlated with individual plant weight in each population (r ranged from +0.53 to +0.91, p <0.01-0.001). The ecological advantages of a weight-related, plastic reproductive strategy are discussed with reference to length of survival of the individual plant.

An Extension of the Concept of Importance Value in Analyzing Forest Communities

Importance values (IV = relative dominance + relative density + relative frequency) were determined for the 12 major canopy species of a mesic north—slope forest in East Tennessee. In addition a fourth term, relative biomass (= above—ground dry weight of a species relative to total stand biomass) was formulated. Comparison of differences between classically determined IV's to IV's containing the relative biomass term indicates that the latter may reflect subtle differences not apparent if biomass is not considered See full-text article at JSTOR

Root growth of four transplant &lt;i&gt;Aman&lt;/i&gt; rice varieties as influenced by NPKS fertilizer

An experiment was carried out at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, during July to December 2006 to study the root growth of four Transplant Aman rice varieties as influenced by NPKS fertilization. The experiment was laid out in a split-plot design with three replications. The experiment consisted of four varieties viz. BRRI dhan30, BRRI dhan31, BRRI dhan40 and BRRI dhan41; and four levels of fertilizers viz. 0, 50%, 100% and 150% of the recommended dose of NPKS. BRRI dhan41 had better performance in all root parameters. All root parameters except number of roots hill-1 performed better at high level of fertilizer. The interaction effect between variety and fertilizer level was significant in respect of number of roots hill-1, fresh weight of root (except at 30 days after transplanting (DAT) and 90 DAT), dry weight of root, fresh weight of above ground plant part (except at 30 DAT and 90 DAT) and dry weight of above ground plant part (except at 90 DAT). Keywords: Root growth; Rice varieties; NPKS fertilizer DOI: 10.3329/jbau.v6i2.4816 J. Bangladesh Agril. Univ. 6(2): 235-238, 2008