EFFECT OF SOIL HYDROTHERMAL REGIMES ON THE PERFORMANCE OF SAFFLOWER PLANTED ON DIFFERENT DATES

Soil hydrothermal regimes which can enhance seed germination, seedling emergence and development so that the late planted safflower (Cartham us tinctorius L.) can be competitive in comparison to normally planted crop need to be studied and suitabily modified. Therefore, a split-pl ot field experiment was conducted in Vertisols during 1984-85 and 1985 -86 post-rainy season to determine the influence of planting date (PD1 : Oct. 20; PD2: Oct. 30; PD3 Nov. 10; PD4: Nov. 20; PD5: Nov. 30; PD6: Dec. 10; and PD7: Dec. 20), irrigation (I-1:come-up Irrigation and I- 2: I-1 + branching stage) and straw-mulch(M(0):No mulch and M(1): padd y straw mulch at 10 t ha(-1)) and the interaction on the growth and de velopment of safflower (Cultivar, JSF-7). Germination of safflower com menced earlier in October planting, bur it was significantly higher in November and December plantings. Initiation of emergence and completi on of germination required 153 and 307 cumulative degree days (CDD soi l), respectively. Days to maturity decreased from 163 to 140 in 1984-8 5 and from 156 to 137 in 1985-86 with delay in planting from October t o December. Height, number of branches, number of capsules, seed yield per plant and 1000 seed weight were significantly affected by the dif ferent treatments. Planting of safflower on October 30 and November 10 in both the seasons produced significantly higher seed yield than the other plantings. Branching stage irrigation (I-2) and straw mulching significantly improved all the yield attributes and seed yield of saff lower in both the seasons. The water use efficiency (WUE) was higher i n early plantings than in the later plantings. Higher WUE was obtained under come-up irrigation. Straw mulching increased the WUE, moderated the diurnal variations in soil temperature and provided a better ther mostable regime more congenial for plant roots which resulted in incre ased safflower seed yield.