الفهرس 
INTRODUCTION
Effect of planting date on forage and seed yields and their componentsOnly 14 pages are availabe for public view
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Abstract
The present investigation was undertaken, at Assiut University Experimental Farm, during 2014/2015 and 2015/2016 seasons, to study the effect of planting dates on forage and seed yields production of Egyptian clover varieties, Serw1-, Gemmeiza-1, Giza-6, Sakha-4, Helally and Local variety. Four planting dates were used i.e. 15th September, 15th October, 15th November and 15th December. The randomized complete block design with four replications was used for each planting date in both seasons. Plot size was 10.5 m2. Three cuts were taken from each planting date at 70, 110, and 145 days after sowing, respectively in two seasons. At the time of each cut, the plant height, leaves/stems ratio as well as fresh and dry forage yield were recorded. In addition, after three cuts for each planting date, the crop was left for flowering and seed production. At seed maturity stage the number of inflorescences/plant, number of seeds/inflorescence, seed setting, 1000-seed weight and seed yield/plot were recorded.
The results were statistically analysed and the treatments compared by L.S.D. test. Also, the genotypic stability as estimated by Tai (1971) is a fit analysis to propose the stability of these varieties performance.
The aim of these studies were to determine the influence of temperature conditions resulting from different planting dates on the forage and seed yield production and their components. Also, study the stability of forage seed yields and their components of Egyptian clover varieties when tested under different environments (planting dates x seasons).
The results obtained are summarized in the following:
I- Forage yield and its components:
I.1- Plant height:
Planting dates had a highly significant effect on plant height in both seasons and over two seasons. The tallest plant height was obtained from the plants sown on 15th October in both seasons, i.e. 93.2 and 92.6 cm, respectively. Moreover, varieties showed significant differences in the plant height in both seasons and over two seasons. Serw-1 variety significantly gave the tallest plant height over planting dates, while, local variety gave the shortest plant in first, second and over two seasons.
I.2- Leaves/stems ratio:
Leaves/stems ratio was influenced highly significant by the different sowing dates in both seasons and over two seasons. Comparison among the four planting dates showed that planting date at September 15th resulted in the highest leaves/stems ratio of 44.5, 43.5 and 44.0% in first, second season and over two seasons, respectively. Moreover, leaves/stems ratio decreased gradually and reached the minimum value at the December 15th planting date in both seasons and over two seasons.
With regard to the varieties showed highly significant differences in leaves/stems ratio in both seasons. Local variety gave the highest leaves/stems ratio of 49.5, 51.8 and 50.7 was obtained when sowing was performed on September 15th in first, second and over two seasons, respectively. While, Serw-1 produced the lower leaves/stems ratio in both seasons and over two seasons.
I.3- Seasonal fresh forage yield (kg/plot)
Seasonal fresh forage yield was affected highly significantly by the different studied sowing dates in both seasons and over two seasons. The seasonal fresh forage yield significant decreased as planting date was delayed (December 15th) and early plants sown at September 15th. Also, the maximum seasonal fresh forage yield/plot were 142.9 and 142.7 kg/plot which were obtained from planting sown on November 15th and October 15th in 2014/2015 and 2015/2016 seasons, respectively. Concerning the seasonal fresh forage yield of the different varieties under study, Helally variety produced the highest fresh forage yield of 121.3 and 121.3 kg/plot in 2015/2016 season and over the two seasons, respectively.
I.4- Seasonal dry forage yield (kg/plot):
The results showed that planting dates had highly significant differences on seasonal dry forage yield of the four planting dates which were 10.8, 14.3, 17.3 and 22.9 kg/plot in 2014/2015 season and 8.9, 16.8, 16.3 and 17.9 kg/plot in 2015/2016 season, respectively.
Over two seasons, no significant differences were noticed in seasonal dry forage yield between commercial varieties of berseem clover (Serw-1, Gemmeiza-1, Giza-6, Sakha-4 and Helally). But significant differences were noticed between each of commercial cultivars with local variety.
II- Seed yield and its components:
II.1- Number of inflorescences/plant:
Number of inflorescences/plant was affected highly significant by the different planting dates in 2014/2015, 2015/2016 and over two seasons. The highest number of inflorescences/plant of 45.8 and 56.3 which were obtained from plants sown on November 15th and October 15th 2014/2015 and 2015/2016 seasons, respectively.
The plants sown at the September 15th and December 15th produced the lowest number of inflorescences/plant of 31.8 and 34.1 over the both seasons, respectively.
Comparisons between the number of inflorescences/plant of the six varieties over all planting dates, revealed that Sakha-4 variety produced the highest number of inflorescences/plant of 38.7, 46.2 and 42.5 in the first, second seasons and over two seasons, respectively.