The effects of sowing date and other factors on growth, yield and nitrogen uptake, and on the incidence of pests and diseases, of winter barley at rothamsted from 1981 to 1983

Abstract

SummaryMultifactorial experiments on winter barley cv. Igri grown after potatoes were made from 1981 to 1983 on silty clay loam soils at Rothamsted. All tested combinations of seven factors, each at two levels: with and without autumn pesticide (aldicarb), two sowing dates (September or October), with and without a fungicidal seed treatment (‘Baytan’), with and without spring and summer fungicides, two amounts of nitrogen, two times of applying nitrogen and with and without a growth regulator (‘Terpal’). Growth, development, yield, nitrogen uptake, pests and diseases were monitored. Sowing in September, fungicide sprays in spring and summer, and the growth regulator had the largest mean benefits on grain yield (+0·80, +0·56 and +0·34 t/ha respectively). Some factors interacted with sowing date; thus aldicarb, the fungicide sprays in spring and summer and the later timing of N all increased yield more on the September-than on the October-sown barley. The larger yields on the September-sown plots were associated with more ears/m2 (978 v. 744) and, in spite of fewer grains per ear (17·8 v. 20·1), more grains per m2 (17·6 v. 14·7 × 103), but lighter grains (39·2 v. 42·3 mg). The largest yields each year (ca. 8.0–8.5 t/ha) were obtained from September-sown barley fully protected from pests and from pathogens in spring and summer and given N in April rather than in March.The aphid vectors of barley yellow dwarf virus were sufficiently common and infective in two of the three autumns to infect the September-sown barley sufficiently that their control by aldicar b enhanced yield. Nematodes, slugs and dipterous stem borers were not numerous enough to be damaging in any year. Mildew in autumn was controlled by the seed treatment, but effects on yield were inconsistent. Mildew in spring and summer was more abundant on the October-than on the September-sown barley; it was controlled by fungicide sprays, which increased yield significantly each year. Leaf blotch was more abundant on the September-sown barley.

Effects of nitrogen timing and frequency of fungicide applications on grain yields of winter barley in Ireland

“…The results confirm many previous findings that nitrogen timing often has a small but significant effect on the yield of winter barley and that results are not always consistent from year to year (Evans & Hough 1984;Conry 1986Conry , 1990Widdowson et al 1986;Harris et al 1987). However, nitrogen timing had little or no effect on the amount of foliar necrosis due to disease.…”

“…Some experiments have shown that applying most of the nitrogen in April instead of March gave significantly greater yields (Bainbridge et al 1980;Penny el al. 1986;Widdowson et al 1986;Conry 1990), while others have shown only small increases which were often non-significant (Evans & Hough 1984;Conry 1986;Harris et al 1987). Different results were often obtained in different years (Evans & Hough 1984;Conry 1986;Penny et al 1986).…”

The effects of grazing on components of grain yield in winter barley

“…The advantages in higher grain yield of sowing winter barley in late autumn (September) in the U.K. are well documented (Widdowson et al 1986). In New Zealand, autumn sowing offers higher grain yield and the opportunity to graze ) but the yield penalty to grazing is not known.…”

Nitrogen leaching losses under a less intensive farming and environment (LIFE) integrated system

“…This work among others (e.g. Widdowson et al 1986) demonstrates the effectiveness of robust early plant growth in providing a sink for soil N. However minimizing the risk of disease is central to the LIFE system and this precludes early sowing. Cover crops have proved to be an effective means of reducing N leaching loss before a spring sown crop but their cost and the need for additional herbicide puts them outside normal LIFE practice.…”