Top PDF On-farm cocoa yields increase with canopy cover of shade trees in two agro-ecological zones in Ghana

On-farm cocoa yields increase with canopy cover of shade trees in two agro-ecological zones in Ghana

On-farm cocoa yields increase with canopy cover of shade trees in two agro-ecological zones in Ghana

2016 ). It must be stated here that even though it may not be biologically plausible that the yield keeps on increasing with increasing CC, however, within the observed data range with CC up to a level of approximately 30% we do not see a decrease in yield with CC. This is substantiated by recent findings of Andres et al. ( 2018 ) who found increased number of pods up to a level of 30% –50% shade, after which yields declined. Although this may seem to be at odds with the common perception that shade results in decreasing yield, we find that there is no con flict between this study and previous findings from con- trolled or semi-controlled experiments (e.g. Ahenkorah et al., 1987 ; Cunningham & Arnold, 1962 ). These studies were carried out under high-input conditions and showed higher yields in open systems than in shaded cocoa systems. Even though farmers in our study applied fertilizer and other agrochemical inputs, the quantities applied by small-scale farmers are usually below the recommended doses needed to optimize yields in full-sun grown cocoa (Appiah, Sackey, Ofori-Frimpong, & Afrifa, 1997 ). Instead, farmers tend to apply low amounts of fertilizer (Baah, Anchirinah, & Amon-Armah, 2011 ) with irregular use of fungicides and insecticides, meaning that natural maintenance of soil fertility as well as pest and disease control by non-chemical means become more important. These natural processes may be more prominent in a diverse system with emergent shade trees. Indeed, Beer, Muschler, Kass, and Somarriba ( 1998 ) suggested that shade can be bene ficial under low input scenarios. Specific to Ghana, Isaac, Timmer, and Quashie-Sam ( 2007 ) docu- mented an increase in nutrient uptake by cocoa trees Figure 3. Observed yields (points) against canopy cover desig-
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Tree diversity and canopy cover in cocoa systems in Ghana

Tree diversity and canopy cover in cocoa systems in Ghana

Abstract Cocoa (Theobroma cacao L.) growing systems in Ghana and West Africa consist of diverse tree species and densities. This study was conducted to determine factors that influence tree species configurations and how tree characteristics affect canopy cover in cocoa farms. Eighty-six farmers and corresponding farms were selected in a systematic approach in four districts across two agro-ecological zones in Ghana. Results show that men tend to have larger farm sizes, higher tree density and diversity than women. Tree density and canopy cover of shade trees were low on large farms, but diversity increased with increasing farm sizes. Even though there was a significant correlation between diameter at breast height and crown area for all species investigated, tree species differed considerably in their crown area and thus the amount of ground cover provided. Current recommendations for shade are usually expressed in number of trees per ha, and our results suggest that these should be refined to reflect the effects of species, the size of their diameter at breast height and the crown area.
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Influences of shading and fertilization on on-farm yields of cocoa in Ghana

Influences of shading and fertilization on on-farm yields of cocoa in Ghana

Data were collected from 11 and 13 farms in the Ashanti and Western regions, respectively. Age of the cocoa trees ranged between 8 and 28 years, often with several ages being present on individual farms. This range is considered to be the economically favourable age of cocoa trees (Obiri et al., 2007 ). Farms in each region were selected such that they were at least 2 km apart in each community. These farms represent traditional cocoa systems in which cocoa seeds were sown on previously cleared forestlands with extremely variable CC of shade trees, spacing and age. On each farm, four circular plots of radius 10 m (341 m 2 area) were delineated, two with a tree in the middle forming a canopy above the cocoa trees and two without any shade trees in the plots. One shaded and one no-shade plot were fertilized (see later), leaving one shaded and one no-shade plot as controls. Hence, the experiment can be described as a full factorial design with two factors, shade/no-shade and fertilizer/no- fertilizer, replicated on the 24 farms (blocks). The shade trees comprised 22 different species with varying ecological classifications and guilds (Table S1).
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Characterization of cocoa production, income diversification and shade tree management along a climate gradient in Ghana

Characterization of cocoa production, income diversification and shade tree management along a climate gradient in Ghana

There is a need to increase the adoption of climate smart technologies in cocoa to sustain its production [ 6 , 14 ]. Understanding the existing characteristics of cocoa production, per- ceived climate change and drought effects, income diversification and management of shade trees in cocoa growing systems in different climatic regions within the cocoa belt should be the first step toward the design of promising adaptation pathways [ 15 ]. Knowledge of existing cocoa agroforestry systems is important in developing interventions and tools to aid farmers with proper management strategies. A key determinant of farming systems is the variation of agro-ecological zones in which the crops are cultivated [ 16 ] and hence characterizing cocoa production systems along a climatic gradient becomes justified. Characterization of shade tree species in cocoa growing systems is an important component of the identification of existing systems [ 17 ]. This could support location and system specific adaptation since agro-ecological zones for cocoa are being altered by changing climatic conditions, especially in areas close to the forest-savannah transition zones [ 4 ]. In the context of climate change, shaded cocoa sys- tems have been identified as an appropriate strategy for increasing resilience and improving agro-ecosystem functioning at plant, plot and landscape levels [ 10 , 12 , 13 , 18 – 21 ]. Although potential soil water competition between shade and cocoa trees in cocoa agroforestry systems have been noted as a potential limitation under marginal cocoa climate [ 22 ]. Lower yields have also been reported for agroforestry systems under relatively lower rainfall locations in the Ashanti region of Ghana [ 23 , 24 ], this could be compensated via income diversification. Conse- quently, the documentation of agroforestry systems distribution between agro-ecological zones is a necessary step towards identifying and optimizing climate change adaptation strategies.
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Agro-ecological assessment of the vegetation cover of Poland s soils

Agro-ecological assessment of the vegetation cover of Poland s soils

At a farm level, crop rotation and farmland structure are the factors that infl uence cropping structure and soil-pro- tective function of vegetation. The favourable value of the vegetation cover index of arable lands is shown by the Nor- folk-type rotation which includes a legume-grass mixture (Harasim, 2000, 2002). That type of crop rotation should be employed in operations specializing in organic farming. In organic farms cropping structure usually meets the cor- rect crop rotation requirements with regard to fertilization and pest and disease management (Tyburski, 2005). Indi- ces of soil coverage by winter crops and winter catch crops found in the majority of farms with substantial surpluses of nitrogen balance point to increased hazards related to leaching of nitrogen and to poor protection against erosion (Kuś, Krasowicz, 2001). Catch crops grown between two main crops may play a signifi cant role in improving that indicator (Duer et al., 2002; Fotyma, Kuś, 2000; Vereijken, 1997). A survey carried out in 105 farms with different shares of permanent grasslands in the province podlaskie revealed that with an increase in the share of permanent grasslands in total farmland vegetation cover index for ar- able lands was signifi cantly decreased (r = -0.40) whereas that for total farmland was increased (r = 0.82); (Harasim, Madej, 2008).
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Postharvest practices and mycotoxins of maize in three agro-ecological zones of Tanzania

Postharvest practices and mycotoxins of maize in three agro-ecological zones of Tanzania

Mycotoxin extractions were performed by adding 50 mL of 65% ethanol to the sub-samples followed by handshaking for three minutes. The mixture was allowed to settle for about two minutes, then the supernatant was drawn by uses of a three-mL syringe (BD Luer-Lok™, 1 Becton Drive, Franklin Lakes, NJ 07417, USA) passed through a sterile syringe filter of 0.45 microns (Corning Incorporated, Corning, NY 14831, Germany) and collected in a clean test tube, and labeled appropriately. Five hundred µL of sample diluent was added to the red dilution cup (provided in the kits) and 100 µL of the filtrate was added to the red dilution cup and mixed up and down five times. Then, 100µL of the filtered dilute extract solution was pipetted and transferred onto the white sample cup (provided in the kits), and the Reveal Q + strips were inserted for either aflatoxin, fumonisin or zearalenone, and then incubated for six minutes. After the incubation, the developed strips were removed and inserted into a Reveal AccuScan Pro 2.0 Reader System (620 Lesher Place, Neogen® Corporation, Lansing, MI 48912 USA) to determine aflatoxin, fumonisin or zearalenone content of the sample. The Reveal Q + assay is quantitative for total aflatoxins, fumonisin, and zearalenone with a range of detection of 2–150 ppb, 0.3-6 ppm and 50-1200 ppb for aflatoxin, fumonisin, and zearalenone, respectively. All maize samples were analyzed in duplicate.
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Oxidative Stability and Its Effects on the Quality of Oil Extracted from E. tirucalli trees in Different Agro-Ecological Zones of Tanzania

Oxidative Stability and Its Effects on the Quality of Oil Extracted from E. tirucalli trees in Different Agro-Ecological Zones of Tanzania

oxidation stability of oil. However, the amount, types and stability of these antioxidant substances in E. tirucalli plant parts were not determined due to limited capacity. Similar findings were reported by different studies which pointed out that antioxidant activities and oxidation stability of oils may be related to their contents of fatty acids which reduced oil deterioration. For example, Meriod et al., (2005) and Baldioli, et al., (1996) reported low oxidation stability and a remarkable antioxidant activity in Sunflower oil due to similar reasons. Again, the antioxidant activities of 3,4- dihydroxyphenylethanoland and phenyl acids (caffeic acid, p-coumaric acid, ferulic acid, syringic acid, and vanillic acid) have been reportedly high in virgin olive oil (Mariod, et al., 2006; Mariod, et al,. (2008). On the other hand, results demonstrated that, regardless of the poor quality of oils obtained from different stem diameters of E. tirucalli bark samples in different agro- ecological zones. There were differences in qualities (oxidative stabilities) of oil (Table 4.1) among stem diameters between different agro-ecological zones used in the present study. One-way ANOVA (Table 4.2) results in Table 4.2 reveals that, these differences in the oxidative stabilities of oil extracted from the wildly grown E. tirucalli among different stem diameters and between different agro-ecological zones were significant at the p < 0.05 level. Also, despite their differences, but results (Table 4.1) show that there were no clear cut trends in the increasing qualities of oil from lower to higher stem diameters within and across agro-ecological zones i.e., oils from trees having larger stem diameters did not produce higher oxidative stabilities than oils from trees with small stem diameters.
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The distribution, infestation levels and effects of honeybee parasites and pathogens on colony performance in two agro-ecological zones of Uganda

The distribution, infestation levels and effects of honeybee parasites and pathogens on colony performance in two agro-ecological zones of Uganda

Honeybee viruses pose significant threats to the health of the honeybee, Apis mellifera. In this study, the distribution of honeybee RNA viruses was investigated in two highland agro-ecological zones of Uganda each with an altitudinal gradient and varying land uses. The aim was to understand the landscape infection rates and the extent to which the common RNA viruses were affecting honeybee colony strength and productivity. Honeybee samples from colonies without any observable health problems were collected during the dry and wet seasons between December 2014 and September 2015. The samples were screened for common RNA viruses using PCR based techniques. Five honeybee viruses were detected in both the eastern and western highland agro-ecological zones of Uganda. These viruses include: Deformed wing virus (DWV) (51.9%), Black queen cell virus (BQCV) (20%), Acute bee paralysis virus (ABPV) (9.5%), Lake Sinai virus (LSV) (2.5%) and Sacbrood virus (SBV) (2.5%). Four of these viruses (DWV, BQCV, ABPV and SBV) were detected in feral colonies. Furthermore, multiple RNA viruses were prevalent in Ugandan honeybee colonies during the wet season. We show that the numbers of multiple honeybee virus infections were correlated to elevation, height of hive placement and distances to potential water sources, suggesting that environmental factors modulate honeybee viral infestation rates. Furthermore, Varroa infestation levels were positively correlated with the number of viral infections suggesting that Varroa was vectoring the viruses. However, surprisingly no honeybee viruses were detected in the sampled Varroa mites from virus-positive colonies. Increased viral diversity in Ugandan honeybee colonies reduced their performance. Based on these findings, honeybee health monitoring programs are urgently needed to keep track of the interactions between African honeybee races, viral pathogens and Varroa mite vectors.
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Rock Phosphate Solubilisation by Strains of Penicillium Spp. Isolated from Farm and Forest Soils of three Agro Ecological Zones of Cameroon

Rock Phosphate Solubilisation by Strains of Penicillium Spp. Isolated from Farm and Forest Soils of three Agro Ecological Zones of Cameroon

The three fungi strains were obtained from soils collected in three out of the five agro ecological zones of Cameroon: The High Guinea Savanna Zone II, the southern plateau raises northward to the grassy, rugged Adamawa Plateau. This feature stretches from the western mountain area and forms a barrier between the country's north and south. Its average elevation is 1,100 meters and its temperature ranges from 22 °C to 25 °C with high rainfall. The Western Highlands Zone III, an irregular chain of mountains, hills, and plateaus known as the Cameroon range extends from Mount Cameroon on the coast (Cameroon's highest point at 4,095 meters) almost to Lake Chad at Cameroon's northern tip. This region has a mild climate, particularly on the Western High Plateau, although rainfall is high. Its soils are among Cameroon's most fertile, especially around volcanic Mount Cameroon. This area has been delineated by the World Wildlife Fund as the Cameroonian Highlands forests ecoregion. The Bimodal Humid Forest Zone V, the South Cameroon Plateau rises from the coastal plain to an average elevation of 650 meters. Equatorial rainforest dominates this region, although its alternation between wet and dry seasons makes it less humid than the coast. This area is part of the Atlantic Equatorial coastal forests ecoregion. In general, the climate varies with terrain, from tropical along the coast to semiarid and hot in the north. Exceedingly hot and humid, the coastal belt includes some of the wettest places on earth. Top soils (0-25 cm depth) were collected from forest and farmed locations of these agro ecological zones for strains isolation and characterization.
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Cocoa  Canopy  Replacement  to  Increase  Productivity and  Plant  Resistance  to  Vascular  Streak  Dieback

Cocoa Canopy Replacement to Increase Productivity and Plant Resistance to Vascular Streak Dieback

ICCRI and Kendenglembu estate. Canopy replacement technique in Kendeng- lembu was done by side cleft grafting on primary branches and top grafting on plagiotropic branches of primary branches. Number of grafted shoots per plant, i.e. 1, 2, 3, 4, 5 and 6 was used as treatments using Sca 6 and Sulawesi 1. The 12 treatments were arranged in randomized complate block design, each treatment replicated 6 times and 10 plants per treatment. Growth of shoot, canopy coverage and development of VSD incidence were the main variables. In Kaliwining, side cleft grafting was applied at 1.5 m above soil surface using Sulawesi 1 and Sca 6 clones as the scion and TSH 858 and ICS 60 clones as rootstocks. VSD intensity was observed by scoring method. Cocoa yield was the main variable. The result showed that both techniques caused similar growth rate of the shoots. The rate of canopy covering by resistant clones reduced VSD infestation following Y = -0.7848X + 69.324 (R² = 0.995) equation. Three resistant shoots per tree was effective in reduc- ing VSD inf estation. Four years after grafting were bean yield by using Sulawesi 1 was 434% over control while 360% yield for Sca 6 compared to average control of ungrafted plants of ICS 60 and TSH 858. Polyphenol content of both resistant clones was higher than that on susceptible ones, however transfer mechanism of that substance to the susceptible stocks is still unknown. It is concluded that canopy replacement using productive and resistant clones is considered to be an effective method to overcome VSD problem and to improve cocoa yield.
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Household poultry production and health management practices in two agro-ecological zones of central Tigray, Ethiopia

Household poultry production and health management practices in two agro-ecological zones of central Tigray, Ethiopia

A total of 160 sample farmers, 80 households from each Wereda were selected randomly using lottery method from those households reared at least one chicken in the year. Disease prevention and controlling methods, selection and culling of chickens, management of broody hens and all aspects of chicken management practices like feeding, watering and housing were collected from individual households using pre-tested formal semi structured questionnaire. In addition four focus group discussions with an average group size of 16 individuals were conducted with key-informants (model farmers, elders, women association leaders, experts from ARD and REST office, administrative bodies, youths and extension workers) in both agro-ecological zones. Tape recorder was used to record the forwarded ideas during the group discussion.
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Agro ecological system analysis (AESA) and farm planning

Agro ecological system analysis (AESA) and farm planning

Organic agriculture is based on knowledge, insight and whole farm approaches. The farming system must work for each farmer family. Crop rotation cycles must be based on planning ahead, sometimes more than 2 years, so that different elements of the farm can work together. Intercropping must be based on knowledge on which crops support each other. The surrounding nature must be considered in the planning, e.g. rainfall, animals in the environment, where some of them can be predators and some can eat the crops. Herbs and weeds can prove to be valuable sources of nutrients, medicine or bio-pesticides.
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Yield evaluation of yellow cassava varieties as affected by inorganic fertilizer in two agro ecological zones of Nigeria

Yield evaluation of yellow cassava varieties as affected by inorganic fertilizer in two agro ecological zones of Nigeria

Field experiment was conducted at the International Institute of Tropical Agriculture Ibadan and Ikene substation during the 2012 rainy season to study the effect of variety and Crystallizer fertilizer on the yield of four yellow cassava varieties. Four (4) IITA yellow cassava varieties (IITA TMS 01/1368, IITA TMS 01/1371 and IITA TMS01/1412 and IITA TMS 01/1593), were tested at three different rates (0 kgha -1 , 400 kgha -1 kg/ha and 600 kgha -1 ) in split plot fitted to RCBD. Data collected on yield parameters were analyzed using ANOVA and means were separated with Least Significant Difference. The varieties TMS01/1371 and TMS01/1412 significantly (P ≤ 0.05) produced highest fresh tuber yield of (9.33tonsha -1 ) and (8.99tonsha -1 ) at Ibadan and Ikene respectively. The variety TMS 01/1593 significantly (P <0.05) produced highest dry matter content (35.50%) and total carotene value (7) of all the yellow cassava varieties in Ibadan. It was concluded, that since the variety TMS01/1593 produced highest total carotene content (7.00) and dry matter content (35.50%), it can therefore be recommended for cultivation and consumption in Ibadan to increase the quantity of cassava products and enhance vitamin A intake. Since TMS01/1371 produced the highest fresh tuber yield of (9.33tonsha -1 ) without the application of Crystallizer fertilizer in Ibadan, it can be cultivated in Ibadan to obtain 9.33tonsha -1 fresh. A further research is recommended to determine the rates of Crystallizer fertilizer to increase yields obtainable in both locations.
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SHADE AND ORNAMENTAL TREES

SHADE AND ORNAMENTAL TREES

A. palmatum ‘Bloodgood’ - Bloodgood Maple – (13’x 18’) Rate < 6”. Upright habit. Burgundy foliage throughout the entire growing season. Attractive red samara fruit/seed. New growth is red/burgundy color, aging to gray. Prefers moist soil and afternoon shade for best look. (Zone 5) A. palmatum dissectum ‘ Crimson Queen’-Crimson Queen Japanese Maple- (10’ x 10’) Laceleaf Japanese Maple. A low branching dwarf tree with cascading branches. Lace-like foliage retains color through the summer. (Zone 5) NOT WARRANTED A .rubrum ‘Franksred’ - Red Sunset Maple – (50 x 40’) Rate 1’-2’. A dense, upright crown, with an oval habit. Showy orange-red fall color that lasts for a long time. Requires full sun to partial shade. Prefers moist, well-drained soil, but tolerates clay soils. (Zone 4)
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The Influence of Canopy Cover on the Ecological Function of a Key Autogenic Ecosystem Engineer

The Influence of Canopy Cover on the Ecological Function of a Key Autogenic Ecosystem Engineer

Abstract: Intertidal fucoid algae can function as ecosystem engineers across temperate marine regions. In this investigation we assess the function of the alga dominating rocky reefs in temperate Australia and New Zealand, Hormosira banksii. Invertebrate and algal species assemblages were examined within areas of full H. banksii canopy, areas where it was naturally patchy or absent (within its potential range on the shore) and areas where the intact canopy was experimentally disturbed. Differences in species assemblages were detected between areas with natural variation in H. banksii cover (full, patchy, negligible), with defined species associated with areas of full cover. Differences were also detected between experimentally manipulated and naturally patchy areas of canopy cover. Species assemblages altered in response to canopy manipulations, and did not recover even twelve months after initial sampling. Both light intensity and temperature were buffered by full canopies compared to patchy canopies and exposed rock. This study allows us to predict the consequences to the intertidal community due to the loss of canopy cover, which may result from a range of disturbances such as trampling, storm damage, sand burial and prolonged exposure to extreme temperature, and further allow for improved management of this key autogenic ecosystem engineer.
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How will climate change shift agro-ecological zones and impact African agriculture ?

How will climate change shift agro-ecological zones and impact African agriculture ?

deserts. This is partially offset by small gains in several other AEZs. The net effect of the PCM scenario is a $39 billion loss per year, which amounts to 14% of net crop revenue. Although the CCC scenario predicts a slight gain in cropland area, it predicts a large loss in crop revenues as land shifts into lower valued AEZs. The CCC scenario leads to gains in net revenue from lowland dry savannahs and especially mid to high elevation sub- humid forests but these gains are overwhelmed by losses in deserts and especially lowland humid forests. The net impact is a crop revenue loss of $84 billion per year or 30%. The aggregate effects are broken down by region in Table 7. Each of the regions is affected differently by each climate scenario. The largest losses are suffered by Central Africa (28% and 80% losses under the PCM and CCC scenario, respectively), which accounts for half of the net damages in each scenario. East Africa (11-12% losses) and North Africa (4-7% losses) are affected the least. Losses in Southern Africa increase from 12% under the PCM scenario to 17% under the CCC scenario.
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Using agro ecological zones to promote European collaboration in organic arming research

Using agro ecological zones to promote European collaboration in organic arming research

local problems (US Department of Agriculture, 2006). Matrices are another tool used by decision makers to focus on the important issues when prioritising, with one axis representing options and other axes describing factors such as agro-ecological zones (Mutangadura & Norton, 1999; Fisher et al., 2005).

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Projected impact of climate change on rice yield in two agro-ecological zones in South- Kivu, Democratic Republic of Congo

Projected impact of climate change on rice yield in two agro-ecological zones in South- Kivu, Democratic Republic of Congo

Rice production in South-Kivu is therefore likely to be negatively affected by climate variability already occurring in the region and future changes in climate which are projected to happen (Basak et al., 2010). Recent models projections have for example shown that rainfall reduction and temperature increment over the next 40 years in DRC is expected (Nsombo et al., 2012). However, the nature of future changes in climate in South-Kivu is not well documented and how these changes are likely to affect agriculture, especially rice production among smallholder farmers (Ahmed and Fayyaz-ul-Hassan, 2011). Rice production has an enormous potential to increase both in quantity and potential to address persistent food insecurity challenges in DRC and particularly in South-Kivu but it is still unclear how this potential will evolve under a changing climate situation. This study assessed i) the trend in historical rainfall and temperature in the two agro-ecological zones in South-Kivu and ii) projected change in rainfall and temperature for mid- and end century for selected representative pathways, and iii) the impact of projected climate change on paddy rice yield in two selected agro-ecological zones in South- Kivu, DRC.
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Differential adaptation strategies to climate change in African cropland by agro-ecological zones

Differential adaptation strategies to climate change in African cropland by agro-ecological zones

The regressions confirm that the choices of all the crops are sensitive to climate. In contrast to irrigation choice, most of the seasonal climate parameters are significant. All four seasons are relevant in modeling crop choice in part because it involves many alternatives in the choice set than the binary choice of irrigation. Most of the quadratic terms are also significant indicating second order relationship of the choice of each crop to the corresponding climate variables. However, due to its complex specification in Table 6, it is difficult to interpret these results in terms of climate vulnerability. In Table 7, we calculate marginal effects of an annual increase in temperature and an annual increase in precipitation evaluated at the mean climate for the sample of farms that choose each crop combination. If temperature increases slightly, farmers tend to
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Morpho-Physiological Dynamics of Weedy Rice Seeds Collected from Two Contrasting Agro-Ecological Zones in Sri Lanka

Morpho-Physiological Dynamics of Weedy Rice Seeds Collected from Two Contrasting Agro-Ecological Zones in Sri Lanka

In addition, morphological diversity, not only among the weedy rice populations but also within them, offers an array of traits that could be studied and incorporated to future rice-breeding programs (Griselda et al., 2004). Previous studies have reported that diversity of seed traits such as hull colour in weedy rice is greater than cultivated rice (Fogliatto et al., 2011). Our results showed that great diversity in weedy rice seeds and the favourable characteristics such as high germination percentage, high survival ability, awn less seeds, proper seed shape and pericarp colour can be incorporated into cultivated rice varieties in rice breeding programs. In particular, the awned populations showed the greater diversity in traits that can impact species’ weediness (Fogliatto et al., 2011). We found large variability in germination pattern characteristics known to influence seed bank dynamics and infestation evolution. From an evolutionary point of view, awned populations would be favoured under different environmental and cropping systems, being able to adapt more easily. According to this study, awned populations are usually dormant and influence weedy rice population dynamics and eventually the competitiveness of this weed. Therefore, management practices have essentially to take them into account and be adapted accordingly. Our study also inferred that the morpho- physiological variation of the weedy rice seed populations was not associated with the agro-ecological conditions; for example, the dry and the wet zone. This is probably caused by seed-mediated gene flow via farmers’ frequent exchange of rice cultivar seeds and through other media such as the machinery used for rice harvesting and water canals.
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