No abstract

Two field experiments were carried out at El-Zahraa, Belqas, Dakahlia Governorate, Egypt, during the two summer seasons of 1997 and 1998 on potato cv. Diamant to evaluate the effect of rock phosphate application as a natural source of P in comparison with single super-phosphate (75 kg P2O5 for both sources) and four sources of fertilizers, i.e. farmyard manure, livestock manure, poultry manure and mineral fertilization in addition to their interactions on vegetative growth, tubers quality, total tuber yield and the concentrations of N, P and K (%) in both foliage and tubers.Results indicated that application with rock phosphate increased significantly both fresh and dry weight of foliage plant in the first season and average of tuber weight in both seasons. On the other hand, plant height, number of main stems / plant, total tuber yield ton/fed., tuber dry matter, starch content in tuber, content of N, P and K in foliage and tuber in both seasons were not affected by phosphorus sources (rock or super-phosphate).Mineral fertilization increased significantly plant height, tuber dry matter, content, N and K content in foliage in both seasons, while application of farmyard manure increased average of tuber weight in both seasons. Results also indicated that applying either farmyard manure or mineral fertilization increased significantly the total tuber yield in both seasons. The interaction between rock phosphate and farmyard manure increased total tuber yield and average tuber weight in both seasons.Generally, using rock phosphate, or super phosphate together with farmyard manure at the rate of 15 ton/fed. in addition to 180 Kg N + 96 kg P2O5/fed. increased total yield of tubers / fed., but economically application of rock phosphate would save a considerable amount of phosphate fertilizers and consequently would decrease the total costs/fed. as compared with super-phosphate fertilizer. In the meantime, the price of one ton of rock phosphate powder (Abo-Tartour rook 26-28.5% P2O5) evaluate between 90-110 L.E., whereas the price of one ton of super-phosphate is about 300 L.E. Moreover, application of rock phosphate together with organic manure may help in decreasing the pollution of environment.

Two storage experiments were carried out at Mansoura Horticultural Research Station, Egypt, during the two successive summer seasons of 2007 and 2008. to study the effect of various application techniques (fumigation, dipping and spraying) of natural essential oils; thyme (Thymus vulgaris, Labiatae) and caraway (Carum carvi, Apiaceae) at cold storage (10°C) and ambient temperatures (35/15°C) (day/night) as well as chloropropham (CIPC) on storability, quality and processing of potato (Solanum tuberosum L. cv. Lady Rosetta). The obtained results revealed that all storage treatments differed significantly in all studied characters. Potato tubers treated with thyme or caraway oils and stored at 10°C or ambient temperature showed the lowest significant values of sprouting and weight loss percents in both seasons of the study. Application of thyme oil at cold storage or ambient temperature resulted in the highest value of dry matter as compared with other treatments, in both seasons. Cold storage had significant effect on reducing sugars and total free amino acids, in both seasons. Tubers of control treatment were of the highest significant gibberillic acid content and of lowest significant abscisic acid followed by cold storage and Chloropropham (CIPC), respectively, relative to all treatments in both seasons. All essential oils/ambient temperature or cold storage treatments gave the best quality processing of chips and French fries, i. e., color, taste and crispiness. Application of caraway or thyme oils by fumigation technique/ambient temperature achieved the highest net return in comparison with other treatments. The study suggests that using thyme or caraway oils by fumigation technique on potato tubers at ambient temperature or cold storage as the best safe, natural, good quality, high-benefit treatments and easy to apply in practice as alternatives to chemical retardants.

This study was conducted in two successive summer seasons of 1998 and 1999 on potato cv. Diamant at El-Zahraa, Dakahlia Governorate, Egypt to evaluate the effect of microbein compound (biofertilizer) and four different levels of (N+P), i.e., 45 kg N + 18.75 kg P2O5, 90 kg N + 37.50 kg P2O5, 135 kg N + 56.25 kg P2O5, and 180 kg N + 75 kg P2O5/fed., as well as to the interactions on growth, tubers yield and their components of potato plant. Moreover, the concentrations of N, P, K, nitrate and nitrite in the tubers, were also determined.Results indicated that treating seed potato tubers with microbein before planting increased the plant stand percentage at 25 and 30 DAP, vegetative growth, i.e., plant height, No. of main stems / plant, foliage fresh weight / plant (g), foliage dry weight / plant (%), total tuber yield (ton/fed.), number of tubers/plant, tuber average weight (g), tuber dry matter (%) and the concentrations of NPK in tubers, while, the concentrations of nitrate and nitrite decreased in the tuber by application of microbein during both seasons of 1998 and 1999.Plant height, foliage fresh weigh/plant, foliage dry weight (%), total tubers yield / fed., number of tubers / plant, tuber average weight, tuber dry matter content ,%, concentrations of N, P, K, nitrate and nitrite in the tuber increased by increasing (N+P) levels in both seasons.The interactions between microbein and (N+P) levels recorded positive effect on plant height, foliage fresh and dry weight / plant, total tubers yield, number of tubers / plant, tuber average weight, tuber dry matter conent and the tuber contents of NPK in both seasons. On the other hand, the concentrations of nitrate and nitrite were decreased in tubers during 1998 and 1999 by treating with microbein.Generally, the results indicated that treating seed potato tubers with microbein at the rate of 10.670 kg/ton before planting in addition to (135 kg N + 56.25 kg P2O5)/fed. gave higher total tuber yield / fed. and lower concentration of both nitrate and nitrite in tubers as compared with the recommended dose of N and P fertilizers (180 kg N + 75 P2O5/fed.).Finaly, treating seed tubers with microbein before planting would decrease the required amount of (N+P) fertilizers by 25% / fed. and consequently the total cost production/fed., in addition to reduce the pollution of environment.