قراءة وصفية لنظرية المعرفة عند لايبنيز

إذا كان التفكير الفلسفي منذ القدم قد جعل المعرفة وما يضمن شروط صدقها وعدم كذبها جزءا أساسيا من اهتماماته، فإن تناول هذه الإشكالية ظل دوما مرتبطا بما يميز كل فلسفة، مثلما هو مرتبط من جهة أخرى باللحظة التاريخية وبهيمنة بعض القضايا النظرية خلال تلك الحقبة. وقد تطور تناول هذا الإشكالية، من كونه إشكالية مرتبطة بأرسطو وبلغته الفلسفية والمنطقية التي تقوم على الحدود والقضايا والمقولات، إلى إشكالية الفلسفة الحديثة التي تقوم على سؤال مصادر المعرفة: بين العقلي والحسي-التجريبي، وما يرتبط بذلك من قضايا مثل آليات اشتغال العقل ودور الحسي والعواطف الانفعالات في إنتاج المعرفة والعلم، فضلا عن منزلة الرياضيات ومناهجها في إقامة وتطور المعرفة العلمية والفلسفية بالإنسان والطبيعة. من هنا تأتي أهمية تناول هذا المقال لموقف ''لايبنيز'' (Gottfried Wilhelm Leibniz) من مصادر المعرفة، وذلك للكشف عن أساس نظرية المعرفة ومبادئها انطلاقا من مفهوم الجوهر والموناد وتكامل العلاقة بين الإيمان والعقل، القائم على أساس العناية الإلهية. وقد عمل ''لايبنيز'' على إبراز وجهة نظره من خلال الرد على الفلاسفة السابقين مما يجعله تمهيدا أساسيا لفهم أهمية تلك المواقف وجعل العودة إليها أمرا حاسما في فهم هذه الإشكالية

Productivity of Sunflower Hybrids As Influenced by Sulphur-Nitrogen Nutrition and Varying Plant Population

The present research work was carried out to investigate the effect of sulphur- nitrogen nutrition and varying plant population on productivity of sunflower hybrid at the agronomic research Area, University of Agriculture Faisalabad. Two years field oriented research experiments were conducted for 2006 and 2007. In the first experiment sunflower hybrid Hysun-33, was subjected to four sulphur level (0, 40, 80, 120 Kg ha -1 ) and four nitrogen levels (0, 40, 80,120Kg ha -1 ). The experiment was laid out in RCBD factorial with three replications. In the second experiment three sunflower hybrid viz., FH-331 (early maturing), SF187 (medium maturing) and Hysun-33 (late maturing) were tested at three row spacing (45cm, 60cm and 75cm).The variation in agronomic and physiological characteristics of sunflower was analyzed with varying levels of sulphur and nitrogen. During both years of study sulphur and nitrogen application @ 80 and 140 Kg ha -1 produced maximum achene yield (3167-3000Kg ha - 1 ), which was the out come of better yield contributing attributes (higher leaf area, maximum crop growth rate, better light interception, dominant head size, higher 1000- achene weight).On an average maximum oil yield of 1090 and 1121 Kg/ha were obtained with the application of 80 and 140 Kg ha-1 sulphur and nitrogen, respectively. An increase in protein contents (%) was experienced with increasing sulphur levels, and vice versa with enhancing the nitrogen levels. Radiation utilization efficiency for dry mater and grain was also significantly increased with higher nitrogen rate and sulphur application @ 80 Kg ha -1 . Computation of benefit cost ratio (BCR) revealed that the highest BCR 2.38 was also pertinent to the same treatment in sunflower are 80 and 140 Kg/ha -1 , respectively. In the second experiment the hybrid Hysun-33, which was a late maturing hybrid, not only recorded highest leaf area index, but also experienced maximum crop growth rate, highest plant height, greatest number of achenes, and maximum achene yield. On an average Hysun-33(late maturing type) produced significantly higher achene yield (3033-2888Kg ha -1 ), planted at 60cm apart rows, and SF-187(medium maturing hybrid) harvested maximum achene yield(2783-2740Kg ha - 1 ), when sown at 45 cm wider rows. The early maturing (FH-331,a local hybrid) responded well to the row distance of 45 cm and produced highest achene yield of xv2633-2533 Kg ha -1 . Although, with increasing rows spacing from 45-75cm, the sunflower crop resulted in larger heads, possessing more achenes per head, and heavier individual achene, but the boost in yield of the hybrids FH-331 and SF-187 with decreasing the row spacing (increasing plant population) was principally associated with more achene number per unit area, higher leaf area index and maximum crop growth rate. Therefore, it is concluded that under tropical to semi-arid region like the experimental area (located at 73.09 o East longitude and 31.25 o North latitude and at an altitude of 184 m), the best sulphur and nitrogen doses to get maximum achene yield. Highest achene yield 3084 kg ha -1 was recorded where sulphur was applied at the rate of 80 kg ha -1 for along with 140 kg ha -1 nitrogen. Computation of benefit cost ratio (BCR) revealed that the highest BCR 2.38 was also pertinent to the same treatment in sunflower are 80 and 140 Kg/ha -1 , respectively. Regarding hybrids and their planting density, late maturing hubris like Hysun-33 should be planted at 60 cm apart rows with plant to plant distance of 22.5. Medium and early maturing sunflower hybrids may be preferred to be sown at 45 cm apart rows with plant to plant distance of 22.5 cm.