EFFECT OF SOIL SOLARIZATION AND ORGANIC FERTILIZER ON QUANTITY AND QUALITY OF ONION SEED YIELD

Abstract

Fi el d ex per i ments on onion soil solarizati on were condu cted at Dakahli a, i n a tleld naturally infested with weeds and soil borne pa thogen. Th e well pre pared and mo istened plots with and wit hout lll anu re, were covered with 80Lm cl ear polyethyl ene t arps for the durar i o n of weeks in Augu st and September before planting oni on bulbs l \1r 1wo seaso ns 98/99 a nd 99/2000.

Soi l sol ari zat ion raised the a verage maximum soil temperature to 6-l''C a nd 62°C on soil surface with manure in 1 998 and 1 999, respecti vel y. Corresponding maximum temperature in non solari zed soil., -;oi l surhKe was 55°C and 56°C, respectively. Sol ari zation combined ' · i Lh orga nic m anure increased maxi mum soil surface temperature 4°C 1 ha n sol a ri zatio n onl y. Du ring sola ri zation beneficia l physical and ciwlll ica l c ha nges occur in soil as a result of ind uced high temperature espec i a lly nea r soil su rface. Soil sol a rizati on with and without organic n utnure signitica nt l y red uced Fusurium .'f Jf'. and tot al fungi and bacteria i nl'es\a ti o n. The organic manure appli cation to the no n solari zed soil inc rea sed the densit y of soil pathogens by 26-5 1 % for Fusarium .'fJp., n- 1 6)0/o for total bacteria a nd 784--11 78% for tot al fungi in both seasons Sol a r i zed pl ots ga ve the: l owest number and weight of weeds/ m2 co m pa red t o t he u ntreated pl ots. All an nual broad-l eaved weeds are co n trolled and a nnual grasses a re satisfactory suppressed while perenni a l s weed s part ia ll y controlled. Solari zation and organic manure illlp rovecl o nion p l ant g rowth and flowering. Onion plants o btained with sol a ri zed soil and organic manure were significantly longer, had more n um ber of sprout a nd leave per pla nt, num ber of sca pe per pl ant , height ol' sca pe a n d scape di ameter. Soil solari zation significantly increased

number or seed heads, seed heads weight per plant, average head weight , seed wei ght per seed head, seed yield per plant, I 000 seeds weight and "L't:d y i eld per fed. were increased by abou t I 3, 39, 22, 43, 67, 20 and r1X0 n over non sol ari zed. Orga nic manure also increased significa ntly -;ecd wei ght per head ( 17%), seed weight per plant (23%), I 000 seed \\ei ght ( 11 °/rl) and seed yield per feddan (22%) compared t o those of non P rga nic trea tment. Solarization and orgamc manure also changed the c hemi ca l con stituents of onion seeds.