Small plots of red clover cv. Sabtoron, S123 (diploids) and Hungaropoly (letraploid) were harvested for seed production at two-week intervals from 19 August to 17 October inclusive in 1981, inflorescence appearance rate, bee density and components of yield having been monitored throughout the summer. InRorescence appearance rate reached a maximum at the end of July/early August for Hungaropoly and Sabtoron and during mid-August for SI23, Bee density followed a similar pattern. Florets and seeds per inflorescence and 1000-seed weight decreased as flowering progressed except during the first three weeks in July. Potential seed yield was calculated from the components of yield for the harvests taken on 3 and 18 September. Losses in seed yield (difference between actual and potential) up to and during harvesting, threshing and cleaning were lower in the tetraploid cultivar (27-39%) than the diploid cuitivars (35-55%). Each cultivar had an optimum harvest time before which yield was affected by immature seeds and beyond which it was adversely affected by shedding of inflorescences and seeds and sprouting of seeds on the inflorescences. The optimum time to harvest Sabtoron was early September, Hungaropoly early to mid-September and the late flowering cultivar SI23 mid-September when less than 4% of the inflorescences were still unripe. Seed yield and inflorescences per unit area were lower in the tetraploid cv, Hungaropoly (maximum 542 kg ha"') than diploid cv. Sabtoron and S123 (864 and 897 kg ha"' respectively) although the tetraptoid had heavier seeds.It is concluded that the optimum time to harvest red clover for seed production is about three or four weeks after the end of the period of rapid inflorescence production and that this coincides with the time when only a small proportion of unripe inflorescences remain.

Studies were made on the fodder and seed production of ryegrass (Lolium perenne L.) using twelve treatment combinations with four levels of nitrogen (30, 60, 90 and 120 kg/ha/cut) and three levels of phosphorus (0, 50 and 100 kg P 2 O 5 /ha), laid out in a randomized block design with four replications. The mean of two years indicated that nitrogen at 120 kg/ha/cut increased the green fodder (834 q/ha) and dry matter yield (129 q/ha) significantly over the lower doses. After leaving the same crop for seed production during mid-March, nitrogen at the rate of 60 kg/ha gave the highest seed yield (7.61 q/ha). Beyond this dose the seed yield decreased drastically due to lodging. Phosphorus at the rate of 50 kg P 2 O 5 /ha gave 5% higher dry matter (99.6 q/ha) and 7.4% higher seed yield (7.26 q/ha) over the control.

ObjectiveUnder certain adverse conditions nitrate can accumulate to potentially toxic concentrations in forages like oats (Avena sativa), barley (Hordeum vulgare), maize (Zea mays), sarson (Brassica juncea) and berseem (Trifolium alexandrinum). The conditions under which plants accumulate excessive amounts of nitrates are not fully understood. We hypothesized that excessive use of nitrogenous fertilizers may be responsible for accumulation of nitrate in plants and decided to determine the effect of excess urea application on nitrate accumulation in berseem, berseem+ rye grass (Lolium perenne) (B+RG), breseem + sarson (B+S) and berseem + oats (B+O).MethodsThe crop was sown on the experimental area in the plot sizes of 5X4 m2 in three replications. The crop was sprayed with 5 different concentrations of urea ranging from 1 to 5% and subsequently analyzed for nitrate content.ResultsThe results indicate that the crude protein and nitrate content of berseem, B+RG, B+S and B+O increases with increasing concentrations of urea. The maximum nitrate concentration in B+S was observed at 4% of urea concentration while in B+RG and B+O at 5% of urea.ConclusionThe excessive nitrogen application appears to be responsible for the nitrate accumulation in the forage crops which may lead to large scale livestock losses.