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排序方式: 共有294条查询结果,搜索用时 31 毫秒
281.
Tahir Rehman 《Agricultural Systems》1982,9(1):43-55
This paper defines the criteria of ‘technical’ and ‘economic’ efficiencies. The relationship between these criteria is identified, and its implications are discussed. These two sets of criteria do diverge, with ramifications both at the farm and the national levels. An illustration of their relationship at the farm level is provided by examining the nature of water allocation to crops in the Punjab of Pakistan. The divergences that exist between ‘technical’ and ‘economic’ efficiencies at both farm and national levels are highlighted by considering the process of mechanisation in the Punjab in some detail. Finally, it is pointed out how a ‘systems approach’ can accomodate both the technical and economic criteria and their interaction. 相似文献
282.
283.
Hamid Yaghini Maryam Shirani Azin Archangi Karim Sorkheh Sajad Badfar Chaleshtori Seyed Ehsan Sangi Mahmood Khodambashi Farahnaz Tavakoli 《Euphytica》2013,194(3):305-324
Nineteen agrochemical traits of 20 almond inter-specific backcrosses progenies were evaluated and compared for three consequence years to find out their phenotypic diversity and determine the relationships of fruit quality traits in almond × peach backcrosses breeding progenies. The variation was observed for traits of phenology parameters (blooming time, ripening time), Physical parameters (fruit weight, width, height, shape, thickness, skin pubescences, colour and flower type), chemical parameters (total sugar content, soluble solids content and acidity) and sensory parameters (attractiveness, taste, and flavor) and yield. Many fruit characteristics that are important to breeders are present in this collection. A high variability was found in the evaluated almond progenies and significant differences were found among them in all studied quality attributes. Year-by-year variations were observed for majority of traits. A significant correlation was found among the fruit height, fruit width, skin pubescences and yield. Fruit height showed a significant positive correlation with fruit weight and fruit thickness and some other traits and a negative correlation with the titratable acidity, skin pubescences and fruit flavour. A high negative correlation was found between the fruit weight and titratable acidity (?0.8). Low coefficients were got between the flower colour and skin pubescences. In addition, principal component analysis it possible to established similar groups of genotypes depending on their quality characteristics and to study relationships among pomological traits in almond progenies evaluated. 相似文献
284.
Zhao Ben Adama Traore Ata-Ul-Karim Syed Tahir Guo Yan Liu Zhandong Xiao Junfu Liu Zugui Qin Anzhen Ning Dongfeng Duan Aiwang 《Precision Agriculture》2022,23(3):748-767
Precision Agriculture - Accurate and timely assessment of crop water status is imperative for in-season irrigation scheduling in crop production. The canopy water stress index and water deficit... 相似文献
285.
Tahir Karasahin Hasan Alkan Fatma Satilmis Sukru Dursun Huseyin Erdem 《Reproduction in domestic animals》2021,56(12):1555-1561
This study aimed to determine the effect of flunixin meglumine treatment during and after the transfer of in vivo produced embryos to Angus (cows) and Holstein (cows and heifers) breeds of cattle on pregnancy rate. Holstein cows were used as donors in the study. A double dose of prostaglandin F2α was administered to the recipient animals for synchronization. Uterine flushing was performed in donors on day 7 after artificial insemination. A total of 295 transferable embryos were obtained. These embryos were transferred to Angus cows (n = 85), Holstein heifers (n = 80) and Holstein cows (n = 130). After the transfer, these animals were divided into three subgroups. The first subgroup (TI) was administered flunixin meglumine during embryo transfer, and the second subgroup (TII) was administered flunixin meglumine both during embryo transfer and on days 8 and 9 after the transfer. The third subgroup (TIII) was not administered anything and it was considered the control group. Pregnancy examination of the recipients was performed on days 30–35 after the transfer using real-time ultrasonography. The pregnancy rates after embryo transfer were found to be 43.52% in Angus cows, 42.5% in Holstein heifers, and 24.61% in Holstein cows (p < .05). When the animals were not classified according to breed, the pregnancy rates in subgroups TI, TII and TIII were found to be 29.29%, 45.10% and 29.79%, respectively (p < .05). In addition, the pregnancy rates were higher in TII and TIII subgroups of Angus cows and Holstein heifers compared to that of Holstein cows (p < .05). As a result, the pregnancy rates obtained after embryo transfer in Angus cows and Holstein heifers were found to be higher than that in Holstein cows. In addition, it was concluded that the administration of flunixin meglumine during and during/after embryo transfer has a positive effect on pregnancy rates in Angus cows and Holstein heifers. 相似文献
286.
Khurram Bashir Nasir Mahmood Khan Sultana Rasheed Muhammad Salim 《Paddy and Water Environment》2007,5(2):73-81
Pakistan is well known for its basmati rice with long grain and aroma, as well as for non-basmati indica varieties; however
average yield is lower as compared with other countries. Besides, cultural practices, the main reason for low productivity
in Pakistan is that, local varieties are susceptible to different biotic and abiotic factors like insect pests, diseases,
drought, and salinity. Different approaches have been undertaken in Pakistan to tackle these problems through traditional
breeding of selection and crossing, mutation breeding, somaclonal variation as well as plant transformation studies in recent
past. For variety development, the most successful examples arose from traditional breeding that produced famous basmati varieties
like Basmati 370, Basmati 385 and Super basmati, and non-basmati varieties such as IRRI-6, DR-82, DR-83, DR-92, Swat-I and
Swat-II, which earn a significant share of foreign exchange every year. Six varieties have also been developed through mutation
breeding, and one through exploitation of somaclonal variation but their contribution to the national economy is not significant.
On the other hand, no variety has been registered as commercial by plant transformation groups. This review discusses the
problems and prospects of rice breeding with special emphasis on basmati rice in Pakistan particularly in Pakistani Punjab
(a major producing area), as well as focuses on future research programs. 相似文献
287.
Ali Kadivar Mohammad Rahim Ahmadi Mahmood Vatankhah 《Tropical animal health and production》2014,46(1):121-126
This study was performed to investigate the effect of periparturient body condition score on the occurrence of clinical endometritis and postpartum resumption of ovarian activity in dairy cows. Eighty-seven lactating Holstein cows, fed with a total mixed ration diet, were included into the study. Body condition scoring (using a 5-point scale with quarter-point divisions) was performed by the same investigator using the visual technique every 2 weeks, from 2 weeks before until 6 weeks after calving. Palpation of the reproductive tract and ultrasonographic assessment of ovaries for detection of corpus luteum using a rectal linear probe was also performed at 2, 4, and 6 weeks after calving. Cows with clinical endometritis had significantly lower body condition score (BCS) than normal cows at all weeks pre- and postcalving, and cows that did not ovulate until 45 days after calving had a significantly lower BCS pre- and postpartum. Cows that did not ovulate until 45 days after calving also lost more BCS from 2 weeks before to 4 weeks after calving. Besides, first ovulation after calving take occurred later in cows with clinical endometritis compared to normal cows (P?<?0.05). In conclusion, low BCS is a risk factor for postpartum endometritis and delayed cyclicity in dairy cows. BCS loss from dry-off to early lactation and occurrence of clinical endometritis can significantly affect postpartum ovarian activity. 相似文献
288.
Relationship between cold resistance,heading traits and ear primordia development of wheat cultivars
Summary For breeding early heading wheat cultivars with resistance to frost damage which are well adapted to dry areas of West Asia and North Africa, the relationships between winter hardiness, ear primordia development and heading traits, i.e. veernalization requirement, photoperiodic response and narrow-sense earliness, were assessed using a total of 30 genotypes of wheat (Triticum aestivum L.) grown in an experiment in Syria. The results of artificial freezing tests indicated that cultivars with good winter hardiness were to be found only in the winter wheat cultivars which required 50 or more days of vernalization treatment. These winter wheat cultivars did not initiate internode elongation without vernalization even at 95 days after planting. Thus their ear primordia were still underground and were protected from frost injury at this stage. Photoperiodic response and narrow-sense earliness were not associated with winter hardiness and earliness of internode elongation, but were related to the number of days to heading after planting. This indicated the possibility for breeding early heading cultivars with winter hardiness and tiller frost avoidance by combining high vernalization requirement, short narrow-sense earliness and neutral response to photoperiod. 相似文献
289.
Thirty progenies of mungbean were produced by crossing 10 true-breeding genotypes with three testers (NM 92, 6601, and their
F1) in a Triple Test cross (TTC) fashion and evaluated with parents in the kharif (July-October) and spring/summer (March-June)
seasons. The data on parents and F1s were analysed for pod clusters on main stem, pod clusters on branches, node of the first peduncle, nodes on main stem and
average internode length to detect epistasis and estimate additive and dominance components of genetic variation. Epistasis
was observed for node of the first peduncle and nodes on main stem in the kharif season. Partitioning of total epistasis revealed
that both additive × additive (i type), and additive × dominance, and dominance × dominance (j and l types) interactions were
significant with prevalent influence of i type interactions on these traits. Both additive and dominance components of genetic
variation were significant for all those traits not significantly influenced by epistasis in either or both seasons. The additive
component was predominant for pod clusters on main stem, pod clusters on branches and average internode length in the kharif
season, and for the node of the first peduncle and nodes on main stem in spring/summer season whereas dominance component
was important for pod clusters on main stem, pod clusters on branches, and average internode length in spring/summer season.
These results suggested that particular generation of segregating population and specific breeding method for selection might
be adopted in each season for the improvement of these traits in mungbean.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
290.
I. S. A. Tahir N. Nakata A. M. Ali H. M. Mustafa A. S. I. Saad K. Takata N. Ishikawa O. S. Abdalla 《Plant Breeding》2006,125(4):323-330
High temperature influences both grain yield and end‐use quality of wheat. The objectives of this study were to evaluate the performance of selected wheat genotypes under heat stress and to examine the effects of high temperatures during grain filling on grain yield and end‐use quality parameters. Fifteen bread wheat genotypes in 2000/2001 and 18 genotypes in 2002/2003 were evaluated under the optimum and late‐sowing conditions of the irrigated hot environment of the Gezira Research Farm, Wad Medani, Sudan. The genotypes comprised released varieties and elite lines from the Sudanese wheat improvement programme. Data collected included grain yield, grain weight and grain end‐use quality including protein content, protein composition, SDS sedimentation values (SDSS) and gluten strength as determined by mixograph analyses. High temperatures significantly decreased grain yield by decreasing grain weight. Although genotypes exhibited variation in magnitude of response, results indicated that high temperature during grain filling increased both soluble and insoluble protein contents, SDSS, mixograph peak height (MPH) and the descending slope at 2 min past peak (MDS). In contrast, mixograph peak time (MPT) and the curve width at 2 min past peak (MCW) were significantly decreased. Flour protein correlated positively with SDSS, MPH and MDS and negatively with MCW. MPT correlated negatively with MDS and positively with MCW. Results indicate that high temperature increased both soluble and insoluble protein contents, SDSS and MPH, and hence the gluten strength, but decreased flour mixing time and tolerance and hence the dough elasticity. Variation observed among genotypes suggests that grain end‐use quality could be improved under high temperature conditions utilizing the available variability; however, it might require evaluation under various growing conditions. 相似文献