Home About us Contact
|
Home About us Contact | ||
|
|
||
Flowering Crops (flowering + crop)
Kinds of Flowering Crops Selected AbstractsAlternative pollinator taxa are equally efficient but not as effective as the honeybee in a mass flowering cropJOURNAL OF APPLIED ECOLOGY, Issue 5 2009Romina Rader Summary 1. ,The honeybee Apis mellifera is currently in decline worldwide because of the combined impacts of Colony Collapse Disorder and the Varroa destructor mite. In order to gain a balanced perspective of the importance of both wild and managed pollination services, it is essential to compare these services directly, a priori, within a cropping landscape. This process will determine the capacity of other flower visitors to act as honeybee replacements. 2. ,In a highly modified New Zealand agricultural landscape, we compared the pollination services provided by managed honeybees to unmanaged pollinator taxa (including flies) within a Brassica rapa var. chinensis mass flowering crop. 3. ,We evaluate overall pollinator effectiveness by separating the pollination service into two components: efficiency (i.e. per visit pollen deposition) and visit rate (i.e. pollinator abundance per available flower and the number of flower visits per minute). 4. ,We observed 31 species attending flowers of B. rapa. In addition to A. mellifera, seven insect species visited flowers frequently. These were three other bees (Lasioglossum sordidum, Bombus terrestris and Leioproctus sp.) and four flies (Dilophus nigrostigma, Melanostoma fasciatum, Melangyna novae-zelandiae and Eristalis tenax). 5. ,Two bee species, Bombus terrestris and Leioproctus sp. and one fly, Eristalis tenax were as efficient as the honeybee and as effective (in terms of rate of flower visitation). A higher honeybee abundance, however, resulted in it being the more effective pollinator overall. 6. ,Synthesis and applications. Alternative land management practices that increase the population sizes of unmanaged pollinator taxa to levels resulting in visitation frequencies as high as A. mellifera, have the potential to replace services provided by the honeybee. This will require a thorough investigation of each taxon's intrinsic biology and a change in land management practices to ensure year round refuge, feeding, nesting and other resource requirements of pollinator taxa are met. [source] Mass flowering crops enhance pollinator densities at a landscape scaleECOLOGY LETTERS, Issue 11 2003Catrin Westphal Abstract To counteract the decline of pollinators in Europe, conservation strategies traditionally focus on enhancing the local availability of semi-natural habitats, as supported by the European Union's Common Agriculture Policy. In contrast, we show that densities of bumblebees, an important pollinator group in agroecosystems, were not determined by the proportion of semi-natural habitats in agricultural landscapes. Instead, bumblebee densities were positively related to the availability of highly rewarding mass flowering crops (i.e. oilseed rape) in the landscape. In addition, mass flowering crops were only effective determinants of bumblebee densities when grown extensively at the landscape scale, but not at smaller local scales. Therefore, future conservation measures should consider the importance of mass flowering crops and the need for management schemes at landscape level to sustain vital pollination services in agroecosystems. [source] Salinity-related desertification and management strategies: Indian experienceLAND DEGRADATION AND DEVELOPMENT, Issue 4 2009G. Singh Abstract High concentration of salts in the rootzone soil limits the productivity of nearly 953 million ha of productive land in the world. Australia, followed by Asia, has the largest area under salinity and sodicity. Most of the salt-affected soils and brackish ground water resources are confined to arid and semiarid regions and are the causative factors for triggering the process of desertification. The problem of salinity and sodicity has degraded about 6·73 million ha area in India. Secondary salinization associated with introduction of irrigation in dry areas like Thar desert in the western part of the country and Sharda Sahayak in Central India have caused desertification due to rise of salts with the rise in ground water level. Large scale cultivation of prawns using sea water in coastal Andhra Pradesh and elsewhere rendered about 2.1 million ha area unfit for agriculture. Similarly, 30,84 per cent ground water in north-western states of the country is either saline and /or brackish and is unfit for irrigation. Use of marginal quality water for irrigation has rendered several thousand ha of productive land unfit for cultivation. The Central Soil Salinity Research Institute was established in 1969 at Karnal to develop sustainable and eco-friendly technologies for reclamation and management of salt-affected soils and judicious use of marginal quality waters. The institute has developed location-specific techniques for reversion of salinity related desertification in India. Salient findings of research during the last three decades and more are presented in this review. This paper deals with (a) classification, nature and extent of salt-affected soils and poor quality water in India, (b) case studies/socio-economic concerns of salinity related desertification, (c) chemical, hydrological and biological approaches in use for rehabilitation of salt-affected soils, (d) guidelines for safe and productive use of marginal quality ground water through cyclic and mixed mode and precision irrigation techniques, (e) successful rehabilitation case studies, (f) alternate land use practices such as raising forest plantations, horticulture, agroforestry, high value medicinal, aromatic and flowering crops, etc., (g) technological, social, economic and environmental impacts and (h) future line of research. Issues requiring policy initiatives to halt salinity-related desertification are also discussed in this review paper. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||