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ranged from November 22, 1978 to March 15, 1979 and the intervals were more
evenly distributed over this period. 1o ensure good germination in the first date,
an irrigation was given immediately after planting. Except for this, the whole
experiment was raised under rainfed condition. The total seasonal rainfall was
only 246 mm. As an average of 20 genotypes, the November-planted crop yielded
more than 3000 kg/ha, and there was almost a linear decrease in yield as the
planting date was delayed by various intervals up to March 15 (Fig. 2). The
increase in the mean yield was 69, 128, 193 and 277% when the planting was
advanced from March 15 to February 15, January 11, December 17 and Novem­
ber 22, respectively. Thus advancing the date of planting even to late or mid­
winter proved substantially better than the early spring and late spring plantings.
This observation is interesting from the point of view of the need for flexibility in
the cropping system of the rainfed agriculture in dry areas.
As in 1977-78, the studies in 1978-79 were also conducted under fungicidal
control as the seeds of Ascochyta-resistantcultivars were not available at that
stage for large-scale trials. However, during 1979-80 season, several promising
genotypes with an acceptable degree of tolerance to ascochyta blight became
available. Hence, their response to the spread in the planting date from early
winter to spring, was evaluated under rainfed condition (total seasonal precipitation
427 mm), along with several others making a total of 20 genotypes. Some of
these genotypes were susceptible to ascochyta blight and were thus affected by
the disease in the winter planting, in spite of the fungicidal spray, because of a
heavy buildup of inoculum and favorable weather conditions for the spread of the
disease. The individual yield data of some selected genotypes including four
tolerant and one susceptible (ILC 1929) lines, as also the mean yield of all the 20
genotypes, are presented in Tab. 2.
The yield of ILC 482 cuhivar increased by 69, 145 and 249%, respectively,
under February 13, December 19 and November 20 planting dates over the yield
under March II planting. Averaged over all the genotypes,the planting in winter
(November 20) resulted in a 118% higher yield than from the spring ph,nting
(March 11). These results reemphasize the point that substantial gains in yield
can be obtained by advancing the date of planting and that this advantage is
particularly higher in the genotypes which have resistance to ascochyta blight in
addition to good agronomic characters.
A more detailed analysis of the performance of an ascochyta blight tolerant
cultivar, ILC 482, in relation to the date of planting is provided in Tab. 3. The
yield of straw, which is economically important in the farming systems of the
region, is also increased substantially by winter planting over spring planting,
following a trend parallel to that of grain yield with no major change in the
harvest index. The water-use efficiency of the crop, as computed by relating the
grain yield to the total seasonal precipitation (427 ram), increases in winter
planting following obviously the trend similar to the grain yield.