The information collected through multi-environment testing of wheat genotypes not only provides basis to identify promising genotypes but also to ascertain their yield potential and the genetic gains. For this purpose, in the presented study, the data originated from the Yunnan provincial Regional Yield Trials (RYT) conducted during 2006 and 2018 was used. During this period, 107 genotypes were evaluated at 18 locations under Upland Wheat (UW) management scheme, while 116 genotypes were evaluated at 21 locations under Field Wheat (FW) management scheme. By adopting standard statistical approaches and through repeated elimination procedures, 7 genotypes emerged as promising for UW and 11 for FW cultivation. These genotypes have genetic variance >1 and 44/33% higher average yield than that of UW/FW genotypes. Most of these promising genotypes were tested during 2016 and 2018 cropping seasons. This indicated a good genetic gain of around 0.7 t/ha in recent years from that of base year. These genotypes, however, needs to be further evaluated in diverse environments suitable for spring type wheat cultivation to ascertain the extent of their interaction with wider environmental conditions and possibility of using in local breeding programs of those target environments.

This study was conducted to identify desirable wheat germplasm for superior hybrid cross combinations through 1) identifying the best parents with high combining ability (CA) and 2) estimating heterosis effects. Two thermophoto-sensitive-genic-male-sterile lines (K456s and K78s) as female parents and 60 restorer lines as males were crossed according to line × tester hybridization method. The observed variation for most of the nine studied characters and <1 ratio for general (G)/specific (S) CA suggested governance of non-additive gene action. The GCA for K456s was higher than K78s in six out of nine characters, while restorers 2016Y2-2776 and 2016Y2- 4117 had the highest in five characters. The crosses K78s/R31 and K456s/R2 had highest positive SCA values in five and six characters, respectively. The crosses K78s/R43 and K456s/R21 had the overall highest significant positive heterosis estimates for the best cross with respect to yield plant-1and has the potential for utilization in hybrid wheat breeding program.

The effect of photothermal quotient at anthesis and maturity on kernel m-2, kernel weight (KW) and kernel yield were examined in experiments involving three different genotypes such as: Chakwal-50, Wafaq-2001 and GA-2002 sown at five different sowing times (Planting windows) for two years (2008-09 and 2009-10) at the National Agricultural Research Center (NARC) Islamabad. Photothermal quotient (PTQ) was calculated at anthesis (PTQ1) and maturity (PTQ2) for two years. A direct relationship was observed between photothermal quotients, kernel m-2, kernel weight and kernel yield for all planting windows and genotypes. The maximum value (213.15) of photothermal quotient was recorded when crop was grown on 28th Oct, 2008 (PW2) during the first year and minimum value was observed (143.82) for PW5 (25th Dec, 2009) during the second year. Decrease in photothermal quotient was observed from PW2 to PW5, whereas correlation analysis depicted positive and significant association with individual kernel weight, kernel m-2 and kernel yield with PTQ. The correlation coefficient (r) between kernel m-2 and PTQ1 was 0.5103, while the correlation between PTQ2, individual kernel weight (0.6375) and yield (0.6507) exhibited significance. The outcomes of photothermal quotient and the relationship established through these experiments between kernel m-2, KW and kernel yield and PTQ may be used as a road map to minimize yield losses and select genotypes and managements according to availability of climatic resources. Key words: Wheat, photothermal quotient, kernel weight, solar radiation, environment.