Crop Cycle Duration Research Articles

Application of EPIC model to assess climate change impact on sorghum in southern Italy

The EPIC (Environmental Policy Integrated Climate) model was used to assess the effects of climate change on sorghum hay (Sorghum bicolor Moench.) in Southern Italy under different future climatic scenarios. The aim of this study was to compare the results of sorghum simulation obtained with a climatic baseline generated dataset with those obtained using several future datasets. The study area was located in the Capitanata plain (southern Italy). The EPIC model was calibrated and validated using experimental data sampled from a two-year experiment (2008-2009) of sorghum carried out in the experimental farm of the CRA. The baseline simulation was based on daily climatic data generated by mean of a statistical downscaling process applied on an empirical dataset including 55 years (1951-2005). The forecasting simulations data were derived by a statistical downscaling process applied on climatic projections of three general circulation models: CCSM3, ECHAM and HadCM3 and were referred to two IPCC scenarios (A2 and B1). Each general circulation models and every scenarios were run for three periods: 2011-2040, 2041-2070, 2071-2100 and so, 18 forecasting simulations were run and compared with the generated baseline. The simulation results highlight, for all three GCMs and for both scenarios, possible trends for sorghum hay in the future such as: decrease of biomass yields, crop cycle duration and irrigation volume, while an increase of irrigation water efficiency and daily evapotranspiration. These trends resulted more evident in the A2 than B1 scenario and in the last future 30-year period of simulation. With the A2 scenario a decrease up to 5 t ha-1 was obtained for dry plant biomass and a shortening up to 20 days for crop cycle duration in the third 30-year future period. CCSM3 and HadCM3 models gave results more similar to each other, different by ECHAM model that did not produce large difference between A2 and B1 climatic scenarios. EPIC model was able to simulate the response of sorghum to climate change and, based on the results obtained, some mitigation strategies could be proposed, such as: earlier sowing time or choice of cultivars with shorter growing cycle.

ADAPTABILITY OF IRRIGATED RICE TO TEMPERATURE CHANGE IN SAHELIAN ENVIRONMENTS

SUMMARYTo assess genotype adaptability to variable environments, we evaluated five irrigated rice genotypes, three new varieties, WAS161, a NERICA, IR32307 and ITA344, and two controls: Sahel 108, the most popular short-duration variety in the region, and IR64. In a field experiment conducted at two locations, Ndiaye and Fanaye, along the Senegal River, rice was sown on 15 consecutive dates at one month intervals starting in February 2006. Yield (0–12.2 t ha−1) and crop cycle duration (117–190 days) varied with sowing date, genotype and site. Rice yield was very sensitive to sowing date and the associated temperature regimes. Spikelet sterility due to cold stress (T < 20 °C) was observed when the crops were sown in August (Ndiaye), September (Ndiaye and Fanaye) and October (Ndiaye and Fanaye), and heat stress (T > 35 °C) resulted in spikelet sterility when sowing took place in April (Ndiaye and Fanaye) and May (Fanaye). For all experiments the source and sink balance was quantified and showed that yield was most limited by sink size when sowing between July and October. Variety WAS 161 was least affected by genotype × environment interactions, resulting in lower interactive principal component values. An increase in minimum temperature of 3 °C could decrease spikelet sterility from 100 to 45%. These changes in temperature are likely to force rice farmers in the Senegal River to adjust the cropping calendar, e.g. to delay planting or to use heat-tolerant genotypes.

METHODOLOGICAL CONSIDERATIONS ON BANANA (MUSA SPP.) YIELD DETERMINATIONS

Farmers, researchers, extension officers and policy makers need reliable yield data on banana (Musa spp.) to make informed decisions. There are no standard yield determination methods available for Musa research. Production patterns and types vary distinctly in time and space. This requires special attention when expressing yields as unit mass per unit area per unit time (t ha -1 y -1 ). Determining banana yield is challenging because: (a) bunch yields are often expressed as fresh weight, but edible dry matter percentage can vary strongly between cultivars and environments; and (b) bunch yields often include the peduncle for which often no uniform cutoff point is used. To obtain realistic and valid yield data and to compare Musa yields with those of other crops, the edible dry matter content needs to be determined and considered. In addition, many cultivars have a highly variable rate of plants reaching flowering and bunch production. Too often, yield calculations are made with the assumption that 100% of the plants produce, whereas in many fields up to 70% of the plants do not produce, especially in lowland plantain fields. Plant densities in farmer fields are often highly variable, which requires careful consideration of (a) the definition of a banana plot; (b) the size of the banana plot; and (c) the number of plants in a banana plot. Often, banana clusters consist of several mats of the same generation, leading to underestimations of the number of mats per unit area. We propose that the definition of a single banana mat is a family of plants with interconnected living corms. Crop cycle duration varies strongly as a function of cultivar, altitude, soil fertility, drought stress, and pest and disease infestation. It can vary from less than one year to over two years, leading to large (>50%) yield differences per unit time between and within cultivars. This paper describes the sources of errors and proposes measures to avoid incorrect or incomplete yield determinations.

Influence of Pratylenchus coffeae and Meloidogyne spp. on plant growth and yield of banana (Musa spp.) in Vietnam

AbstractThe objective of the presented study was to look at the effect of Pratylenchus coffeae and Meloidogyne spp., the two major nematode species associated with banana ( Musa spp.) in North Vietnam, on the plant growth and yield of cv. Grand Naine (AAA) and four local banana cultivars, Ngu Tien (AA), Hot (BB), Ben Tre (AAA) and Tay Tia (ABB). Inoculated plants were compared with nematode-free control plants in terms of plant growth, crop cycle duration and yield under field conditions in Hanoi, North Vietnam. Infection with P. coffeae did not affect the crop cycle duration or the plant height, the pseudostem girth or the number of standing leaves at harvest of any of the cultivars, but did significantly reduce the bunch weight of cv. Ngu Tien from 6.6 to 5.3 kg (20% reduction), the bunch weight of cv. Tay Tia from 7.3 to 5.9 kg (19% reduction) and the bunch weight of cv. Grand Naine from 6.9 to 6.0 kg (13% reduction). The bunch weight of cvs Hot and Ben Tre was not significantly affected. The number of hands of the inoculated and the control plants did not differ for any of the cultivars but infection with P. coffeae resulted in a 34% reduction in the number of fingers of cv. Grand Naine (from 67 to 44 fingers). The number of fingers of the other cultivars were not affected by inoculation with P. coffeae. Infection with Meloidogyne spp. did not affect the time from planting to harvest for any of the cultivars, but the time from planting to shooting was increased from 367 to 387 days for cv. Ngu Tien. The plant height and the pseudostem girth at harvest of cv. Grand Naine were significantly reduced by 27% and 18%, respectively. The number of standing leaves as well as the plant height and the pseudostem girth at harvest of the other cultivars were unaffected. Infection with Meloidogyne spp. significantly reduced the bunch weight of cv. Ngu Tien from 6.6 to 5.1 kg (23% reduction) and the bunch weight of cv. Grand Naine from 6.9 to 5.6 kg (19% reduction). The bunch weight of cv. Hot was unaffected. Infection with Meloidogyne spp. reduced the number of hands of cv. Ngu Tien by 14% (from 6.2 to 5.4 hands) the number of fingers of cv. Grand Naine by 25% (from 67 to 50 fingers). The number of hands and fingers of the other cultivars were not affected. The results indicate that in areas where the burrowing nematode, Radopholus similis, is not present, other nematodes, especially Meloidogyne spp., may become more important in terms of damage and yield loss.

Weed and Insect Communities in Wheat Crops with Different Management Practices

Biotic adjustments to changes in crop management practices are reflected in the presence or absence of weed and insect populations. The pattern of response and the causes that drive them are important to reveal the main factors involved in molding the structure of an agroecosystem and its dynamics. In this study, weed and insect communities were characterized in wheat (Triticum aestivum L.) crops from the Rolling Pampas with different cropping histories. Surveys were performed in fields that were selected randomly from those located on highlands with typical Argiudol soils and cultivated with conventional tillage. Fields, weeds, and insects were classified with cluster analysis, and weed and insect associations were determined using agronomic variables with canonical correspondence analysis (CCA). The classification of the data resulted in six floristic groups and seven insect groups that characterized different weed and insect communities. Three weed and insect communities associated with the number of years with annual cropping after a pasture that lasted for several years, the duration of wheat crop cycle, and soybean as a preceding crop were identified.

Produção da bananeira 'Nanicão' em diferentes densidades de plantas e sistemas de espaçamento

O objetivo do presente trabalho foi verificar o efeito de diferentes densidades de plantio e sistemas de espaçamento sobre a produção da bananeira 'Nanicão', avaliando-se os primeiros quatro ciclos. Quatro densidades (3.333, 2.222, 1.666 e 1.333 plantas ha-1) e dois sistemas de espaçamento (retângulo e triângulo) foram testados para as condições de Piracicaba,SP. O aumento da densidade de 1.333 para 3.333 plantas ha-1 diminuiu a massa do cacho em 15% a 20%, em decorrência do menor número de frutos por cacho, massa e tamanho do fruto. A produção foi sempre maior com o aumento da densidade, porém não ocorreu o mesmo quanto à produtividade. Até o terceiro ciclo, a produtividade das plantas no tratamento de maior densidade superou a das demais. No quarto ciclo, não houve diferença de produtividade entre as plantas, nas densidades testadas, em razão do aumento na duração do ciclo de produção do plantio mais denso. Comparado com o retângulo, o sistema de espaçamento em triângulo promoveu maior massa do cacho no primeiro ciclo e produtividade levemente superior ao longo dos quatro ciclos.

Plant density studies with banana (cv. Williams) in a subtropical climate. III. The influence of spatial arrangement

SummaryAt the standard recommended density of 1666 plants ha−1, the influence of rectangular (3 m rows×2 m in the row), hedgerow (4×1.5 m) and tramline (6 m rows alternating with 2 m rows × 1.5 m) plant spacings was investigated on the growth and productivity of ‘Williams’ banana over five cropping cycles. There were no significant differences in pseudostem or leaf morphology, leaf emergence rate or crop cycle duration between spacings. There were also no bunch mass differences between spacings in the P and R1 cycles, whereas in the R2, R3 and R4 cycles, tramline bunches were respectively 7.6, 7.0 and 9.0% smaller than those from rectangular-spaced plants (P<0.05 in the R4). Overall productivity (yield per annum) was similarly reduced by 7.4% from rectangular to tramline plantings, although this was not significant. Productivity of the hedgerow plantings was intermediate at 4.6% less than the rectangular.