Different Levels Of Irrigation Water Research Articles

Valor nutritivo de cultivares de cana-de-açúcar sob irrigação

Objetivou-se avaliar a composição químico-bromatológica e a digestibilidade in vitro da matéria seca (DIVMS) de cultivares de cana-de-açúcar, sujeitas a diferentes lâminas de irrigação. Foram avaliadas as cultivares RB 96-1003; RB 94-3206; RB 72-454; RB 01-2018; VAT 90-212; RB 01-2046 e RB 92-579, que recebiam as lâminas de irrigação em 100%; 80%; 60% e 40% da evapotranspiração real da cultura (ETc) em delineamento em blocos completos, casualizados, e arranjo fatorial em três repetições. Cada parcela foi constituída por sete linhas duplas de plantio, em que o sistema de irrigação utilizado foi o gotejamento subsuperficial com emissores autocompensantes. Aos 12 meses após o plantio, as canas foram cortadas para determinação dos teores de matéria seca (MS), matéria mineral (MM), proteína bruta (PB), matéria orgânica (MO), fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), extrato etéreo (EE) e DIVMS. As cultivares RB 94-3206 e RB 01-2018 se destacaram positivamente em relação aos teores de PB, enquanto a RB 96-1003 destacou-se de forma positiva para a DIVMS. Com a lâmina de irrigação de 100% da ETc foram obtidos maiores teores de MS e menores valores de DIVMS em relação às demais.

Spectral reflectance characteristics of sugar beet under different levels of irrigation water and relationships between growth parameters and spectral indexes

AbstractThe use of spectral vegetation indexes requires an experimental background. In this study field trials were conducted during 2004 and 2005 on sugar beet. Seven different irrigation treatments were applied. During the experiments soil water status, spectral reflectance, leaf area, plant dry weight and yield were observed and recorded. Water and yield relationships were determined and water use efficiency (WUE) was calculated. The relationships between spectral vegetation indexes and agronomic parameters were determined. According to the results, excessive irrigation does not increase yield and when nearly 500 mm water is used, maximum WUE is 7.2 kg m−3. The highest determination coefficients were calculated between LAI and simple ratio (SR, R2 = 0.59), sugar beet yield and soil adjusted vegetation index (SAVI, R2 = 0.91). Consequently, spectral indexes, which can be calculated from data obtained through either handheld spectroradiometers or satellites, could prove useful tools for agricultural monitoring and management. Copyright © 2010 John Wiley & Sons, Ltd.

Bayesian Inference for Generalized Stochastic Population Growth Models with Application to Aphids

SummaryWe analyse the effects of various treatments on cotton aphids (Aphis gossypii). The standard analysis of count data on cotton aphids determines parameter values by assuming a deterministic growth model and combines these with the corresponding stochastic model to make predictions on population sizes, depending on treatment. Here, we use an integrated stochastic model to capture the intrinsic stochasticity, of both observed aphid counts and unobserved cumulative population size for all treatment combinations simultaneously. Unlike previous approaches, this allows us to explore explicitly and more accurately to assess treatment interactions. Markov chain Monte Carlo methods are used within a Bayesian framework to integrate over uncertainty that is associated with the unobserved cumulative population size and estimate parameters. We restrict attention to data on aphid counts in the Texas High Plains obtained for three different levels of irrigation water, nitrogen fertilizer and block, but we note that the methods that we develop can be applied to a wide range of problems in population ecology.

Response of onion ( Allium cepa L.) to different levels of irrigation water

The study analyses the response of onion to different irrigation levels with microsprinkler irrigation system. The four treatments comprised different ratio of irrigation water (IW) to cumulative pan evaporation (CPE) namely 0.60 (T 1), 0.80 (T 2), 1.0 (T 3) and 1.20 (T 4). Irrigation had significant effect on growth parameters of onion and subsequently influenced the crop yield. The best yields were recorded from T 3 and T 4, associated with the higher percentage of bulbs having diameter greater than 45 mm. Protein content in bulbs was highest when associated to T 1, but the loss in marketable produce during the storage was also highest in T 1. Irrigation water use efficiency and water use efficiency both were highest in T 2 and then declined with the increase in irrigation. Hence, in water constraint situation, T 2 would be the most appropriate irrigation level for onion production with microsprinkler irrigation system. Production functions of yield versus irrigation water applied and yield versus crop evapotranspiration were found to be polynomial. The developed functions can be used as a guide to yield potential allocation decision related to limited irrigation water.

Response of lemongrass ( Cymbopogon flexuosus ) under different levels of irrigation on deep sandy soils

The growth and herbage and oil production of East Indian lemongrass (Cymbopogon flexuosus) in response to different levels of irrigation water (IW) [0.1, 0.3, 0.5, 0.7, 0.9, 1.1, 1.3 and 1.5 times cumulative pan evaporation (CPE)] were evaluated on deep sandy soils at the research farm of the Central Institute of Medicinal and Aromatic Plants, Lucknow, from 1991 to 1993. In general, an increment in the level of irrigation increased the plant height up to 0.7 IW:CPE ratio. The response of irrigation levels on tiller production of lemongrass differed with the season of harvest. Maximum tillers/clump during the 2nd, 3rd, 6th and 7th harvests were in response to irrigation levels 0.9, 0.5, 0.7 and 0.7 IW:CPE ratio, respectively. Oil content had an inverse relationship with the levels of irrigation, specially during the 1st, 2nd, 5th and 6th harvests. Significantly higher herb and essential oil yields were recorded at 0.7 IW:CPE ratio, irrespective of season of harvest. The maximum total herb (22.79 t/ha in first year and 33.11 t/ha in second year) and oil (146.2 l/ha in the first year and 205.3 l/ha in the second year) yields were recorded at 0.7 IW:CPE ratio. The quality of oil with respect to the major chemical constituents (Citral-a, Citral-b and geraniol) was not changed. At the optimum level of irrigation (0.7 IW:CPE ratio) the water used by lemongrass was 118.2 cm for first year and 123.8 cm for the second year. Water-use efficiency was found to be higher (1.66 l oil/ha-cm) in the second year than the first year (1.23 l oil/ha-cm). For optimum yield potential of lemongrass on deep sandy soils of sub-tropical climate, the crop received 17 irrigations in the first year and 14 irrigations in the second year of harvests. Irrigations were made during the dry winter and summer months.

Genotypic and Environmental Variation in Nodal Root Growth of Post-rainy Season (Rabi) Sorghum

SummaryRapid initiation and growth of nodal roots (NR) are critical for the establishment of post-rainy season (rabi) sorghums grown in drying soil. The growth of NR was studied in sorghum in the field when sown at different depths in order to vary the crown depth, when different levels of irrigation water were applied to create different moisture contents in the topsoil, and in a number of cultivars to assess genotypic variability. Variation in sowing depth did not result in differences in NR growth, partly because of the capacity of sorghum to vary the mesocotyl length, which brought the crown to approximately the same depth. Different soil moisture levels in the field affected the elongation rate of NR, but not their initiation. Genotypic variation existed in the thermal time required for NR initiation and rate of elongation. The variation in NR growth was independent of the variation in shoot growth. The genotypic variability in NR growth offers an opportunity for combining root-related traits with useful agronomic characters.